Article

Anammox – A novel microbial process for ammonium removal

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Anammox 1,2 , a process of anaerobic ammonium oxidation, is an innovative technological advancement in the removal of ammonia nitrogen in waste water. This new process combines ammonia and nitrite directly into dinitrogen gas 3 . The anammox reaction can be represented as − + + 2 4 NO NH = N 2 + 2H 2 O. This reaction is carried out by anammox bacteria be-longing to the planctomycete group. Bac-teria capable of anaerobically oxidizing ammonia were not identified earlier and were known as 'lithotrophs missing from 4 . Subsequently, this missing lith-otroph was discovered 1 and identified as a new autotrophic member of the order Planctomycetales. It appears that they might be the most primitive group of bacteria, at the very root of the bacterial tree. Two of the anammox bacteria have been named provisionally 5 : Candidatus 'Brocadia anammoxidans' and Candida-tus 'Kuenenia stuttgartiensis'. The former bacterium was responsible for anaerobic oxidation of ammonia observed in the Netherlands, while the latter organism has been shown to be responsible for ammonia oxidation anaerobically in sev-eral wastewater treatment plants in Ger-many and Switzerland. Interestingly the two species of the anammox bacteria which have been characterized are rarely found together in a single anammox reac-tor, they must have different, as-yet un-known, ecological niches 5 . It is well known that the biological nitrogen cycle plays an important part in the maintenance of nitrogen balance in global biosphere. The conventional bio-logical nitrogen cycle involves microbial fixation of nitrogen gas to ammonia sym-biotically and non-symbiotically which is subsequently converted to organic nitro-gen. The ammonia released from organi-cally bound nitrogen and from man-made activities, is biologically oxidized aero-bically to nitrite and then to nitrate. The resultant nitrate and nitrite are reduced to nitrogen gas by a denitrifying group of bacteria using some electron donors (or-ganic or inorganic compounds). It has been indicated 6 that anaerobic ammonia oxidation also could be a major biologi-cal activity to be included in the nitrogen cycle, thus necessitating its modification. Recently 7 it was discovered that anam-mox makes a significant (up to 70%) contribution to nitrogen cycling in the world's oceans. Figure 1 shows the involvement of anammox process in the biological nitrogen cycle including meta-bolic pathway for anaerobic ammonium oxidation. Initially anammox research 5 was fo-cused on the basic properties of the proc-ess and on providing evidence for its microbial nature and the principles of the nitrogen and carbon metabolism. It appears that the anammox process is based on energy conservation from an-oxic ammonium oxidation with nitrite as the electron acceptor and hydrazine and hydroxylamine as the intermediates. Carbon dioxide is used as the main car-bon source for growth. One of the key enzymes of anaerobic ammonium oxida-tion is hydroxylamine oxidoreductase 8 . Its importance is illustrated by the fact that it constitutes 10% of the total cell protein. It catalyses the oxidation of hy-drazine and hydroxylamine. The enzyme has been located in a membrane-boun-ded, 'organelle' named anammoxasome, in the cytoplasm of the anammox cells 9 . This 'organelle' appears to be the center of anaerobic ammonium oxidation. It is quite likely that its function could be containment of hydrazine. The anam-Figure 1. Involvement of anammox pro-cess in biological nitrogen cycle including metabolic pathway for anaerobic ammo-nium oxidation (adapted from refs 3 and 5).

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... ANAMMOX is an innovative technological advancement in removal of ammoniacal nitrogen from wastewater, carried out by microbial oxidation of ammonia with nitrite to dinitrogen gas occurring under anoxic conditions (Wang et al., 2009;Schmidt et al., 2003;Shivaraman and Shivaraman, 2003). The ANAMMOX reaction is carried out by deeply branched Planctomycetes, such as 'Candidatus Brocadia anammoxidans' and 'Candidatus Kuenenia Stuttgartiensis', 'Candidatus Scalindua', 'Candidatus Anammoxoglobus' which makes use of ammonium as the electron donor (energy source) and nitrite as the electron acceptor as indicated in Eq. (1). ...
... These autotrophs utilize dissolved carbon dioxide or bicarbonate for cell biosynthesis with a slow growth rate (doubling time -11 d) (Jin et al., 2008;Wang et al., 2009;Schmidt et al., 2003;Shivaraman and Shivaraman, 2003;Chamchoi and Nitisoravut, 2007), resulting in hydrazine and hydroxylamine as intermediary metabolites (Chamchoi and Nitisoravut, 2007). In the ANAMMOX process N 2 gas is the primary reaction product along with a small amount of nitrate. ...
... and 0.08-4.64 mg/L, respectively, confirming the ANAMMOX activity in the system (Shivaraman and Shivaraman 2003). ...
Article
ANaerobic AMMonium OXidation (ANAMMOX) process, an advanced biological nitrogen removal alternative to traditional nitrification--denitrification removes ammonia using nitrite as the electron acceptor without oxygen. The feasibility of enriching anammox bacteria from anaerobic seed culture to start up an Anaerobic Membrane Bioreactor (AnMBR) for N-removal is reported in this paper. The Anammox activity was established in the AnMBR with anaerobic digester seed culture from a Sewage Treatment Plant in batch mode with recirculation followed by semi continuous process and continuous modes of operation. The AnMBR performance under varying Nitrogen Loading Rates (NLR) and HRTs is reported for a year, in terms of nitrogen transformations to ammoniacal nitrogen, nitrite and nitrate along with hydrazine and hydroxylamine. Interestingly ANAMMOX process was evident from simultaneous Amm-N and nitrite reduction, consistent nitrate production, hydrazine and hydroxylamine presence, notable organic load reduction and bicarbonate consumption.
... ANAMMOX (ANaerobic AMMonium OXidation) is an innovative technological advancement in removal of ammonia nitrogen from wastewater, carried out by microbial oxidation of ammonia with nitrite occurring under anoxic conditions (Wang et al., 2009;Schmidt et al., 2003;Shivaraman and Shivaraman, 2003). ANAM-MOX process combines ammonia and nitrite directly to dinitrogen 0960-8524/$ -see front matter Ó 2010 Elsevier Ltd. ...
... All rights reserved. doi:10.1016/j.biortech.2010.07.121 gas (Shivaraman and Shivaraman, 2003). Start up of ANAMMOX process is considered difficult owing to the slow growth rate (doubling time -11 days) of ANAMMOX bacteria (Chamchoi and Nitisoravut, 2007). ...
... They utilize dissolved carbon dioxide or bicarbonate for the cell biosynthesis resulting in hydrazine and hydroxylamine as intermediary metabolites. Presence of hydrazine and hydroxylamine in traces adds proof of ANAMMOX process (Shivaraman and Shivaraman, 2003). ANAM-MOX process is generally favorable in environments with long sludge retention time (30-50 days), stable operation, presence of nitrite (<70 mg/L), and the absence of electron donors (such as ammonium ion) that would cause nitrite reduction via denitrification are absent (Berge et al., 2005). ...
Article
Discharge of nitrate and ammonia rich wastewaters into the natural waters encourage eutrophication, and contribute to aquatic toxicity. Anaerobic ammonium oxidation process (ANAMMOX) is a novel biological nitrogen removal alternative to nitrification-denitrification, that removes ammonia using nitrite as the electron acceptor. The feasibility of enriching the ANAMMOX bacteria from the anaerobic digester sludge of a biomethanation plant treating vegetable waste and aerobic sludge from an activated sludge process treating domestic sewage is reported in this paper. ANAMMOX bacterial activity was monitored and established in terms of nitrogen transformations to ammonia, nitrite and nitrate along with formation of hydrazine and hydroxylamine.
... Спільні культури формують гранулярний мул, що забезпечує одночасне проходження аеробних та анаеробних амонійокиснювальних реакцій -окиснення амо нію до вільного азоту через проміжний про дукт нітрит. У середовищі, що оточує гранули мулу, існують аеробні умови, що сприяє розвиткові нітрифікуючих бактерій, тим часом як у центрі гранул існують анаеробні умови і відбувається анамокс-процес [21,22]. Певною модифікацією технології CANON є OLAND (oxygen-limited autotrophic nitri fication-denitrification)-процес -автотрофна нітрифікація-денітрифікація з лімітованою аерацією. ...
... Певною модифікацією технології CANON є OLAND (oxygen-limited autotrophic nitri fication-denitrification)-процес -автотрофна нітрифікація-денітрифікація з лімітованою аерацією. Існують дві технології, що ґрунтуються на цьому процесі: одностадійна система з використанням обертового біореактора (Rotating biological contactor -RBC) та двостадійна система із застосуванням мембранних біореакторів (MBR) [21][22][23]. У результаті здійснення процесу амоній переходить у вільний азот [24]. ...
Article
Full-text available
The results of analysis of the current technologies, as well as their trends and developments in the field of wastewater treatment in Ukraine and the world are given. The legal documents and the system of state regulation and control in the field of sanitation and wastewater treatment in Ukraine have been analyzed. The information about government programs aimed at protecting the natural water bodies is also included. The global trends concerning development of biotechnology in the field of wastewater from nitrogen compounds have been investigated. The analysis of traditional (nitrification-denitrification) and the latest biotechnology wastewater from inorganic nitrogen has been done. Current status of the present key technologies of nitrogen removal from wastewater has been formulated. The main advantages and disadvantages of these biotechnologies are described. It was determined that a major problem in the field of sanitation and wastewater treatment in Ukraine is the usage of outdated technologies and regulatory documentation that is a consequence of the lack of sufficient funding for the sector and the low level of environmental awareness of the government and the population.
... Anammox bacteria have been found to be important in Nr removal processes in various aquatic environments. In addition, anammox bacteria are currently utilized in waste water treatment where they are used as a means of removing ammonium and nitrite [23]. ...
... Dissimilatory nitrate reduction to ammonium processes have also been found in the anammox bacterium, K. stuttgartiensis [84]. DNRA bacteria are capable of producing the substrates (NH 4 + and NO 2 -) for anammox [23]. Therefore, the anammox contribution to N 2 production may be enhanced by stimulating DNRA in soil ecosystems. ...
Article
Full-text available
Green energy and biofuel policy is promoting the replacement of a significant percentage of fossil fuel resources with renewable bioenergy carriers to meet future energy requirements and reduce carbon emissions. However, the global rise in nitrogen pollution, due to increased food and biofuel crop production, has raised environmental concerns. Strategies for managing sustainable energy production while maximizing the benefits should be an important milestone for all biofuel-producing countries. In this article we review the recent literature concerning the use of chemical and biological fertilizers on biofuel crops and the role of the microbial nitrogen cycle in the nitrate and nitrous oxide emissions from various environments. The future potential of microbes for the sustainable production of biofuel-energy crops is discussed.
... Anammox bacteria predominantly catalyze the production of NO 3 − -N when the O 2 content falls below 1%, whereas complete nitrification, driven by the faster growth rate of nitrite oxidizers compared to ammonia oxidizers, occurs at O 2 concentrations above 1% in gas phase. Remarkably, a reactor operating with O 2 levels below 0.5% air saturation efficiently cultivates microbes with varying oxygen requirements [102]. However, the restricted O 2 concentration below 1% stimulates GHP-N 2 O production through the activity of NO 2 − -N and NO reductases, resulting in a loss of 7.2% nitrogen in the DHS. ...
Chapter
Full-text available
The accumulation of ammonium (NH4+-N) and nitrous oxide (N2O-N) in the environment is causing concern due to their ecological impacts and contribution to global warming. Autotrophic nitrogen oxidizers, including aerobic ammonium-oxidizing archaea and bacteria, anaerobic ammonium oxidizer and nitrite oxidizers, play a crucial role in the nitrogen cycle by facilitating the removal of nitrogenous residues from the environment. Nitrogen oxides (NOx) like nitrite (NO2−-N) and nitrate (NO3−-N) are produced as key immediate products during the conversion of NH4+-N or N2O-N. Additionally, these autotrophic microbes utilize carbon dioxide (CO2) for cell synthesis, thereby mitigating the greenhouse effect. Preliminary results pointed out that nitrogen oxidizers could effectively remove NH4+-N and NOx from sewage and wastewater systems at the loading rate lower than 0.5 kg N/m3-day. Moreover, this family could also reduce the greenhouse N2O-N through oxidizing pathway, attaining the maximum reduction of 25.2-fold the annual N2O production.
... SRB and denitrifying microorganism associations could also explain our results. When SRB reduce nitrate/nitrite and produce ammonia nitrogen, the denitrifying bacteria can carry out their anaerobic oxidation (anammox), with generation of dinitrogen gas (Shivaraman & Shivaraman, 2003). ...
Article
Full-text available
Thirty superficial sediment samples were collected in Guanabara Bay in order to identify new trophic state and environmental quality descriptors for coastal systems. A biochemical approach was used for analyzing the quality and quantity of sedimentary organic matter and metabolic bacterial activity. The samples were analyzed for particle size; organic matter, protein, carbohydrate, lipid, biopolymeric carbon, and bioavailable carbon levels; and bacterial metabolic activity. The results show a homogeneous spatial distribution for the anaerobic bacteria web and for biopolymers (carbohydrates>;lipids>;protein). The NE area of the bay displayed sediment lipid levels above 1 mg/g, indicative of organic sewage input. Spatial distribution of the superficial sediments in relation to other variables was not significant (p>;0.05). Biopolymers and labile organic matter showed a significant correlation with the average particle size of 80% of the fine particles. Despite the availability of labile organic matter, under the form of biopolymeric carbon, only 50% of the carbon was available to the trophic web. The bacterial consortia formed by sulfate reducing and denitrifying bacteria sustain the benthic trophic food web in Guanabara Bay.
... Hydroxylamine and hydrazine were present around 0.003 and 0.02 mg/L, respectively. Trace concentrations of hydroxylamine and hydrazine confirms the AnAOB growth in the reactor (Shivaraman and Shivaraman 2003;Third et al. 2005). Positive correlations exhibited between the intermediates (r = 0.397, p ≤ 0.05). ...
Chapter
Full-text available
The generation of solid waste (SW) has a direct connection with the monetary status of individuals and shows in terms of gross domestic product (GDP)/gross national income (GNI). The high-income countries (HICs) have shown a lingering generation of solid waste, mainly municipal solid waste (MSW). The MSW of HICs include organic biodegradable, paper, plastic metal, glass, and other inert waste and reported higher for the United States of America (50.70%), Canada (47%), Germany (22%), Canada (13%), Germany (12%), and Hungary (35%). The solid waste generation (kg/capita/day) was reported remarkably higher in Italy (59.83), followed by Australia (8.47), Switzerland (8.08), Hong Kong (7.18), Denmark, Singapore, and Lithuania. The treatment processes such as composting, landfilling or controlled dumping, recycling, and incineration were commonly followed by the HICs. The HICs are spending 82–250 USD/ton, 70–200 USD/ton, 65–150 USD/ton, 40–100 USD/ton, and 35–90 USD/ton for waste collection, waste to energy conversation, anaerobic digestion, sanitary landfill, and composting, respectively. The HICs such as the USA, Canada, Scotland, UK, Northern Ireland, and European Union have strict guidelines and rules for landfilling. The US Environmental Protection Agency has restricted the open dumping process by enforcing laws, administrative actions, and punishments with penalties. The strict restrictions are also effected to dispose bio-hazardous materials and substances generated from demolition/renovation of the building. Other side, adoption of emerging techniques plays significant role in circular economy for high-income countries.
... Bacteria capable of anaerobically oxidizing ammonium had not been known earlier and were referred as the "lithotrophs missing from nature" (Shivaraman and Geetha, 2003). These missing lithotrophs were discovered and identified as the new autotrophic members of the order of planctomycete, one of the major distinct division of bacteria (Strous et al., 1999a). ...
Conference Paper
Full-text available
CYANOBACTERIAL SPECIES WILL ACT AS POTENTIAL BIOSORBENT FOR HEAVY METALS IN SEWAGE WATER
... The hydrazine and hydroxylamine were in the range of 0.001 to 0.01 mg/L and 0.001 to 0.002 mg/L, respectively. This authenticated the AOB and AnAOB activity [12]. ...
Article
Landfill bioreactors (LFBR) are gaining significant attention as sustainable alternative for conventional landfilling. Nitrogen management is an important issue in landfill bioreactors. The present study is to establish the combined SHARON (single reactor system for high activity ammonia removal over nitrite) and ANAMMOX (anaerobic ammonium oxidation) processes in landfill bioreactors for in situ nitrogen management. Laboratory scale landfill bioreactors (43 L volume capacity) as SHARON-ANAMMOX LFBR were loaded with mined municipal solid waste operated for 147 days at a nitrogen loading rate of 1.2 kg N/m3/d. The results showed a nitrogen removal efficiency of 84% with maximum partialnitritation efficiency of 56% and specific ANAMMOX activity of 0.7 mg Amm-N/mg MLVSS/d was achieved in the LFBR. Nitrogen transformations, biomass development and, hydrazine and hydroxylamine formation authenticated the aerobic ammonium oxidising bacteria (AOB) and anaerobic ammonium oxidising bacteria (AnAOB/ANAMMOX) activities responsible for combined SHARON-ANAMMOX processes in LFBR. 99% of the biogas in LFBR as N2 the end product confirmed the combined SHARON-ANAMMOX processes. The study successfully demonstrated the combined SHARON-ANAMMOX processes for in situ nitrogen management in landfill bioreactors with shorter start-up time and stable operation.
... ANAMMOX (ANaerobic AMMonium OXidation) is an innovative technological advancement in removal of ammonia nitrogen from wastewater, carried out by microbial oxidation of ammonia with nitrite occurring under anoxic conditions [5 -7]. ANAMMOX process combined ammonia and nitrite directly to dinitrogen gas [7]. Start up of ANAMMOX process is considered difficult owing to the slow growth rate (doubling time -11 days) of ANAMMOX bacteria [8]. ...
Article
Release of nitrate and ammonia rich wastewaters into the natural waters promotes eutrophication, aquatic toxicity and deterioration in water quality. Anaerobic Ammonium Oxidation (ANAMMOX) process is an advanced biological nitrogen removal alternative to traditional nitrification – denitrification, which removes ammonia using nitrite as the electron acceptor without oxygen. The feasibility to enrich ANAMMOX bacteria from anaerobic seed culture to start up an Anaerobic Membrane Bioreactor (An MBR) for N – removal is reported in this paper. The seed culture used was anaerobic digester sludge collected from a Sewage Treatment Plant (STP) in Chennai. Stabilization performance of An MBR is reported for a period of 250 days, for the presence of ANAMMOX bacteria and its sustained activity in terms of Nitrogen transformations to Ammonia, Nitrite and Nitrate along with Hydrazine and Hydroxylamine.
... The hydrazine concentration was in the range of 0.001 to 0.003 mg/L and hydroxylamine was around 0.0002 to 0.001 mg/L in the reactors. The trace occurrences of intermediates (hydrazine and hydroxylamine) with the specific anammox activity proved the enrichment of AnAOB [15]. The reactors are validated by the duplicate reactors, which gave 90 -95% correlation. ...
Article
Ammoniacal nitrogen removal by novel processes like Single reactor system for high activity ammonia removal over nitrite (SHARON) and Anaerobic ammonium oxidation (ANAMMOX) processes are currently considered as advantageous than conventional processes. It requires aerobic ammonium oxidising bacteria (AOB) and anaerobic ammonium oxidising bacteria (AnAOB) to conduct the SHARON and ANAMMOX processes. This paper presents the feasibility of enriching the AOB and AnAOB using mined municipal solid waste (MSW) in batch reactors for a period of 37 days. In AOB reactor with nitrogen loading of 0.5 kg N/d showed Partial Nitritation Efficiency of 82.6% with 3.8 × 108 MPN/100mL of AOB population obtained. AnAOB reactor enriched with anammox biomass efficiently removed 78% of ammonia with the specific anammox activity reached up to 0.10 mg NH4-N/mg MLVSS/d. The nitrogen transformations along with the formation of intermediates (hydrazine and hydroxylamine), biomass development, free ammonia and free nitrous acid concentrations in the batch reactors confirmed the enrichment AOB and AnAOB biomass activity using mined MSW.
... SRB and denitrifying microorganism associations could also explain our results. When SRB reduce nitrate/nitrite and produce ammonia nitrogen, the denitrifying bacteria can carry out their anaerobic oxidation (anammox), with generation of dinitrogen gas (Shivaraman & Shivaraman, 2003). ...
Article
Full-text available
Thirty superficial sediment samples were collected in Guanabara Bay in order to identify new trophic state and environmental quality descriptors for coastal systems. A biochemical approach was used for analyzing the quality and quantity of sedimentary organic matter and metabolic bacterial activity. The samples were analyzed for particle size; organic matter, protein, carbohydrate, lipid, biopolymeric carbon, and bioavailable carbon levels; and bacterial metabolic activity. The results show a homogeneous spatial distribution for the anaerobic bacteria web and for biopolymers (carbohydrates>lipids>protein). The NE area of the bay displayed sediment lipid levels above 1 mg/g, indicative of organic sewage input. Spatial distribution of the superficial sediments in relation to other variables was not significant (p>0.05). Biopolymers and labile organic matter showed a significant correlation with the average particle size of 80% of the fine particles. Despite the availability of labile organic matter, under the form of biopolymeric carbon, only 50% of the carbon was available to the trophic web. The bacterial consortia formed by sulfate reducing and denitrifying bacteria sustain the benthic trophic food web in Guanabara Bay
... Deammonification process start-up after enrichment of anammox microorganisms from reject water in a moving-bed biofilm reactor Ivar Nitrogen-rich wastewaters are generated in meat processing, fish canning and yeast factories as well as in the production of nitrogen fertilizers, [1] also, effluents of anaerobic digester contain wastewater with a high ammoniumnitrogen/chemical oxygen demand (NH + 4 -N) ratio. Ammonium and nitrate and organic compounds have effectively been eliminated from groundwater by Valentukeviciene and Albrektiene. ...
Article
Full-text available
Deammonification via intermittent aeration in biofilm process for the treatment of sewage sludge digester supernatant (reject water) was started up using two opposite strategies. Two moving-bed biofilm reactors were operated for 2.5 years at 26 (+/- 0.5 degree C with spiked influent(and hence free ammonia (FA)) addition. In the first start-up strategy, an enrichment of anammox biomass was first established, followed by the development of nitrifying biomass in the system (R1). In contrast, the second strategy aimed at the enrichment of anammox organisms into a nitrifying biofilm (R2). The first strategy was most successful, reaching higher maximum total nitrogen (TN) removal rates over a shorter start-up period. For both reactors, increasing FA spiking frequency and increasing effluent concentrations of the anammox intermediate hydrazine correlated to decreasing aerobic nitrate production (nitritation). The bacterial consortium of aerobic and anaerobic ammonium oxidizing bacteria in the bioreactor was determined via denaturing gel gradient electrophoresis, polymerase chain reaction and pyrosequencing. In addition to a shorter start-up with a better TN removal rate, nitrite oxidizing bacteria (Nitrospira) were outcompeted by spiked ammonium feeding from R1.
... mg/L for hydrazine and 0.0001-0.003 mg/L for hydroxylamine, proved the anammox activity (Shivaraman and Geetha, 2003). The variations in biomass concentrations are in line with gas productions depicted in the Fig. 4c. ...
Article
The main aim of this study is to analyse the feasibility to use aerobic ammonium oxidising bacteria (AOB) and anammox/AnAOB biomass enriched from mined municipal solid waste for in situ SHARON and ANAMMOX processes in laboratory scale landfill bioreactors (LFBR) for ammonia nitrogen removal. For this purpose, three LFBRs were operated as Control (without biomass seed), SHARON (with AOB biomass seed) and ANAMMOX (with anammox biomass seed) for 315days. Results showed nitrogen loading rate of 1.0kgN/d was effectively removed in SHARON and ANAMMOX LFBR. In SHARON LFBR, partial nitritation efficiency reached up to 98.5% with AOB population of MPN of 5.1×10(6)/mL obtained. ANAMMOX LFBR gave evolution of 95% of nitrogen gas as the end product confirmed the ANAMMOX process. Nitrogen transformations, biomass development and hydrazine and hydroxylamine formation authenticated the enriched AOB and anammox biomass activity in landfill bioreactors.
... This process is based on energy conservation through anoxic ammonia oxidation with nitrite as the electron acceptor. Hydrazine and hydroxylamine are intermediate products in the process (Shivaraman and Shivaraman, 2003). Table 2 shows some of the possible reaction steps that could occur in the anammox process. ...
Article
Suboptimal pH and high nitrogenous compounds content in metal industry wastewaters often make using traditional biological treatment methods problematic. It is too early to draw conclusions as to the best technology by comparing novel processes such as OLAND, CANON, SHARON, and ANAMMOX and so on, owing to the fact that most of these new processes are still to be fully tested at pilot and commercial scale. Therefore, it is worthwhile to review the novel nitrogenous compounds removal processes and to look at their potential for use in biological treatment of inorganic wastewaters with reference to the metal industry. The biochemical reactions and enzymes involved in each step of the nitrification and denitrification processes, microbiology of each process, different technologies such as OLAND, CANON, SHARON, ANAMMOX and their operational requirements in evaluating the application of the nitrification–denitrification process to metal industry wastewater are discussed in this review.
... Bacteria capable of anaerobically oxidizing ammonium had not been known earlier and were referred as the " lithotrophs missing from nature " (Shivaraman and Geetha, 2003). These missing lithotrophs were discovered and identified as the new autotrophic members of the order of planctomycete, one of the major distinct division of bacteria (Strous et al., 1999a). ...
Article
Full-text available
In wastewater treatment, nitrogen is being considered a one of the essential parameter as it has significant adverse impacts on the environment. Anaerobic ammonia oxidation (ANAMMOX) is a novel process in which nitrite is used as the electron acceptor in the conversion of ammonium to nitrogen gas. The ANAMMOX process offers great opportunities to remove ammonia in fully autotrophic systems with biomass retention. No organic carbon is needed in such nitrogen removal systems, since ammonia is used as electron donor for nitrite reduction. This paper reviews and summarizes recent developments in nitrogen removal, microbial aspects (occurrence, physiology, microbiology and biochemistry) of ANAMMOX, followed by a qualitative comparison of several components of ANAMMOX technology with conventional nitrogen removal systems and finally addresses the application of the ANAMMOX process for nitrogen management.
... From the temperature dependency of ANAMMOX activity, the activation energy was calculated to be 70 kJ/mol. Strous et al. (1998) Bacteria capable of anaerobically oxidizing ammonium had not been known earlier and were referred as the " lithotrophs missing from nature " (Shivaraman and Geetha, 2003). These missing lithotrophs were discovered and identified as the new autotrophic members of the order of planctomycete, one of the major distinct division of bacteria (Strous et al., 1999a). ...
Article
Full-text available
Landfilling is still a popular way for Municipal Solid Waste (MSW) disposal. Leachate generated from landfills is becoming a great threat to surrounding as it contains high concentration of organic and toxic pollutants. In recent years, due to the advances in knowledge of landfill behavior and decomposition processes of MSW, there has been a strong thrust to upgrade existing landfill technology from a storage or containment concept to a process based approach as a bioreactor landfill. Increasing attention is being given to leachate recirculation in landfill bioreactor as an effective way to enhance microbial decomposition of biodegradable solid waste. High concentrations of ammonia in the leachate may become a hindrance to the effective functioning of bioreactor landfills. Thus, the stabilization of landfill leachate with respect to ammonia is likely to be the factor that determines when the overall landfill can be considered stable. The most likely scenario for ammonia removal is the aerobic treatment of leachate outside of the landfill to convert ammonia to nitrate, followed by use of the landfill as an anaerobic bioreactor for denitrification. Anaerobic ammonia oxidation (ANAMMOX) is a novel process in which nitrite is used as the electron acceptor in the conversion of ammonium to nitrogen gas. The ANAMMOX process offers great opportunities to remove ammonia in fully autotrophic systems with biomass retention. No organic carbon is needed in such nitrogen removal systems, since ammonia is used as electron donor for nitrite reduction. This paper reviews and summarizes the anaerobic solublization of nitrogen in landfill environment, recent developments in nitrogen removal, microbial aspects (occurrence, classification, physiology,
... Recently, the process of anammox, which uses nitrite together with ammonium to produce N 2 , has been observed in several marine ecosystems. This process constitutes another pathway for the elimination of nitrogen through N 2 production and can represent an average of 30% of the total N 2 production (Shivaraman 2003;Thamdrup and Dalsgaard 2002). ...
Article
Full-text available
Seasonal patterns of di-nitrogen fluxes together with denitrification, anammox, and N-fixation rates were studied in sediment in an area subject to strong human pressure via waste water, tributaries and shellfish farming in the Mediterranean Sea (Carteau Cove, NW area of the Gulf of Lion). Ammonium concentration demonstrated no seasonal variation, however, a large increase in its concentration was observed over a 10years period due to intense biodeposition of organic matter. In contrast, nitrate concentration demonstrated no seasonal or long-term (10years) variation. The main processes affecting di-nitrogen flux magnitudes were denitrification and N-fixation. Anammox was only detected occasionally, nevertheless it represented at times up to 39% of the N2-flux. Nitrate reducing processes were variable and denitrification showed a 20-fold increase over the past 10years and might actually have reached its potential maximal activity. Rates of N2 production (denitrification and anammox) were generally higher than those of N-fixation, leading to elimination of nitrogen from the ecosystem.
... An elevated FA concentration was used in combination with other parameters (Table 2), because NOB could acclimatize to a higher FA concentration of around 50 mg/L [22] when using it solely for NOB inhibition. However, the respiration tests performed by Vadivelu et al. [23] confirmed that Nitrobacter spp. ...
Article
Full-text available
A biofilm with high nitrifying efficiency was converted into a nitritating and thereafter a nitritating–anammox biofilm in a moving-bed biofilm reactor at 26.5 (±0.5)◦C by means of a combination of intermittent aeration, low dissolved oxygen concentration, low hydraulic retention time, free ammonia and furthermore, also by elevated HCO−3 concentration. Nitrite oxidizing bacteria (NOB) were more effectively suppressed by an enhanced HCO−3 concentration range of 1200–2350 mg/L as opposed to free-ammonia-based process control where NOBs recovered from inhibition; the respective total-nitrogen removal rates were 0.3 kgN/(m3·d) and 0.2 kgN/(m3·d). The biofilm modification strategies resulted in a shift in bacterial community as the NOB Nitrobacter spp. were replaced with NOB belonging to the genus Nitrospira spp. and were closely related to Candidatus Nitrospira defluvii. A community of anaerobic ammonium-oxidizing microorganisms –uncultured Planctomycetales bacterium clone P4 (closely related to Candidatus Brocadia fulgida) – was developed.
... Ammonium-rich wastewaters (600-2000 mg/L) are generated in wastewater sludge treatment, slaughterhouses, dairies, meat processing, fish canning, yeast factories and in the production of nitrogen fertilizers (Shivaraman, 2003). Even more NH 4 + -N (over 2000 mg/L) may be contained in landfill leachate (Sun et al., 2010). ...
Article
Full-text available
Nitrifying biomass on ring-shaped carriers was modified to nitritating one in a relatively short period of time (37 days) by limiting the air supply, changing the aeration regime, shortening the hydraulic retention time and increasing free ammonia (FA) concentration in the moving-bed biofilm reactor (MBBR). The most efficient strategy for the development and maintenance of nitritating biofilm was found to be the inhibition of nitrifying activity by higher FA concentrations (up to 6.5 mg/L) in the process. Reject water from sludge treatment from the Tallinn Wastewater Treatment Plant was used as substrate in the MBBR. The performance of high-surfaced biocarriers taken from the nitritating activity MBBR was further studied in batch tests to investigate nitritation and nitrification kinetics with various FA concentrations and temperatures. The maximum nitrite accumulation ratio (96.6%) expressed as the percentage of NO2(-)-N/NOx(-)-N was achieved for FA concentration of 70 mg/L at 36 degrees C. Under the same conditions the specific nitrite oxidation rate achieved was 30 times lower than the specific nitrite formation rate. It was demonstrated that in the biofilm system, inhibition by FA combined with the optimization of the main control parameters is a good strategy to achieve nitritating activity and suppress nitrification.
... An association of SRB and denitrification microorganisms could also explain our results. When SRB reduce nitrate/nitrite and produce ammonia nitrogen, denitrifying bacteria can carry out anaerobic oxidation, with generation of gaseous nitrogen (Shivaraman and Shivaraman, 2003). ...
Article
The aim of this work was to quantify the biopolymers associated to esterase enzymes and identify bacterial respiratory activity in four cores collected in Suruí Mangrove, Guanabara Bay - RJ. Biopolymer concentration was 1000 times lower than previously reported in the literature, indicating the need for creating and establishing eutrophication indicative rates and records compatible with tropical coastal systems. The biochemical representative relationships in the cores were equivalent to those from studies on coastal marine environments made in the Northern Hemisphere. The esterase enzymes in the sediment proved efficient in the mineralization of biopolymers, even with preferentially anaerobic metabolic physiology. Despite the lack of incipient geomicrobiological studies, the results highlighted the possible application of microbiology to a better understanding of geological processes.
... Anammox bacteria have a number of unique features, including the use of hydrazine as a free catabolic intermediate, the biosynthesis of ladderane lipids and the presence of an anammoxosome (intracytoplasmic compartment) (Francis et al., 2007). Furthermore, a cyclobutane aliphatic ring was first reported in the dominant membrane lipids of two Anammox bacteria, unlike the common microbialmembrane lipids that normally contain three-, five-, six-, and seven-carbon aliphatic rings (Shivaraman and Shivaraman, 2003). Enriched culture of Anammox biomass has a brown appearance due to high cytochrome content (Jetten et al., 1999). ...
Chapter
Ammonia oxidising bacteria (AOB) and archaea are ubiquitous microorganisms, but their abundance and diversity vary widely across environments and play a crucial role in many ecosystems and aquatic ecosystems in particular. However, characterization of AOB communities require genomic methods as they are difficult to isolate from samples. Although non-toxic to humans, in the short term, ammonia in water systems are harmful to aquatic life both directly and indirectly through the disruption of the ecosystem by promoting the proliferation of algae (a process called eutrophication). Contamination often occurs due to use of disinfectants with chloramines, fertilizers, waste disposal and from natural processes. Due to their natural presence, utilising AOBs to treat water is viewed as an attractive solution, but greater knowledge of their biochemical processes and measurement of their efficacy is required. Ideal for postgraduates and researchers in a variety of disciplines, this book covers the ecology, genomics, physiology and biochemistry of AOBs and their presence in wastewater, and the challenges, opportunities and potential applications for nitrification and ammonia removal.
Chapter
Ammonia nitrogen concentrations in landfill leachate varies around 100–3000 mg/L, considered to be a persistent pollutant in landfill. The nitrogen profile and its mechanism involved in the landfill waste decomposition is explored in detail in this chapter. Various physical, chemical and biological nitrogen removal systems for their merits and demerits are addressed. Among them the novel anaerobic ammonium oxidation (ANAMMOX) process has benefits for nitrogen removal than conventional biological process with lower power requirements and operational expenditure. The foremost challenge in scale-up is the need for large-scale enrichment of AnAOB (or ANAMMOX) bacteria. This chapter presents the study results of successful enrichment of AnAOBs using mined municipal solid waste (MSW) from landfill. Large-scale anaerobic fed batch reactor loaded with mined MSW as seed at a solids loading rate of 1739 g of TS operated for 250 days with nutrient supplement addition. AnAOB enrichment was confirmed based on specific ANAMMOX activity with 0.005–0.10 mg Amm-N/mg MLVSS/d, hydrazine (0.02 mg/L) and hydroxylamine (0.003 mg/L) formation, biomass accumulation – 8200 mg/L with free nitrous acid and free ammonia concentrations of 0.0–0.002 and 0.5–34.0 mg/L, respectively. Ammonia removal efficiency of 87 ± 6 mg/L, nitrite utilization (98%) and nitrate formation (4.6–24.1 mg/L) revealed the AnAOB enrichment using mined MSW for enhanced landfill leachate treatment using ANAMMOX process.
Article
Full-text available
We evaluated groundwater contamination by landfill leachate at a municipal landfill and characterized isotopic and hydrogeochemical evidence of the degradation and natural attenuation of buried organic matter at the study site. Dissolved ion content was generally much higher in the leachate than in the surrounding groundwater. The leachate was characterized by highly elevated bicarbonate and ammonium levels and a lack of nitrate and sulfate, indicating generation under anoxic conditions. Leachate δD and δ13CDIC values were much higher than those of the surrounding groundwater; some groundwater samples near the landfill showed a significant contamination by the leachate plume. Hydrochemical characteristics of the groundwater suggest that aquifer geology in the study area plays a key role in controlling the natural attenuation of leachate plumes in this oxygen-limited environment.
Article
Landfill leachate, generated from the wastes in a landfill, is a type of wastewater with high concentrations of ammonia and organics, causing a serious environmental pollution. Because of its complex and changing characteristics, it is difficult to remove nitrogen from landfill leachate economically and effectively. Hence, nitrogen removal is a significant research priority of landfill leachate treatment in recent years. Biological processes are known to be effective in nitrogen removal. In this work, the biological nitrogen removal treatments were divided into the following processes: conventional nitrification-denitrification process, nitritation-denitritation process, endogenous denitritation process, and anaerobic ammonium oxidation (Anammox) process. This manuscript summarized the theories and applications of these approaches in detail, and concluded that appropriate processes should be selected in accordance with different characteristics of landfill leachate, in order to effectively remove nitrogen from all stages of landfill leachate and reduce disposal costs. Finally, perspective on the challenges and opportunities of biological nitrogen removal from landfill leachate was also presented.
Article
Stabilisation of ammoniacal nitrogen from solid waste and leachate significantly improved by combining novel processes like SHARON (single reactor system for high activity ammonia removal over nitrite) and ANAMMOX (anaerobic ammonium oxidation) with advantages of lower carbon requirements, aeration and N2O emissions. This paper deals with establishing combined SHARON-ANAMMOX processes in situ pilot-scale landfill bioreactors (LFBR). Molecular analysis in LFBR with changes in nitrogen, hydrazine, hydroxylamine confirmed aerobic and anaerobic ammonium oxidising bacteria (AOB & ANAMMOX) as key players in SHARON-ANAMMOX processes. In situ SHARON-ANAMMOX process was established in LFBR with total nitrogen and ammoniacal nitrogen removal efficiency of 84% and 71%, respectively at NLR of 1.2 kgN/m3/d in 147 d, compared to ammoniacal nitrogen removal of 49% at NLR of 1.0 kgNH4-N/m3/d in 336 d feasible in Control LFBR. Nitrogen massbalance demonstrated in situ SHARON-ANAMMOX advantageous than control LFBR with higher nitrogen transformation to N2 (50.8%) and lower residual nitrogen in solid waste (7.7%).
Article
The lipid composition of the microbial community inhabiting activated sludge in a pilot reactor for the anaerobic oxidation of ammonium (anammox) at the Kur’yanovo Treatment Plant (Moscow) has been studied. The fatty acid composition is mostly based on common fatty acids C14–C18 (95%) with both normal and isomeric structures. The biomass of activated sludge was found to contain lipids with the so-called ladderane substances (ladder alcohols and fatty acids) that are common for anammox bacteria: C20-[3]-lad-derane and C20-[5]-ladderane alcohols and C18- and C20-[3]-ladderane and C18- and C20-[5]-ladderane acids. In addition, the native extract contained both simple and compound ethers of the above-mentioned substances with residues of phosphocholine, phosphoethanolamine, and phosphoglycerine. The spectra of the electron impact and tandem mass spectrometry of certain substances have been obtained and published for the first time.
Conference Paper
The traditional nitrogen removal processes do not meet increasingly stringent discharge standards and sustainable demands. A novel, economical and efficient process was originally discovered in a denitrifying pilot plant reactor, namely anaerobic ammonia oxidation. Some significant advantages make the anammox be a milestone in the field of wastewater treatment and attract much attention, such as low biomass yield and cost. In this paper, the physiological properties, molecular techniques, reaction mechanism of the anammox bacteria and the practical applications are summarized in briefly.
Article
Leachate from the municipal solid waste (MSW) landfills contains high concentration of ammoniacal nitrogen that is a major toxic pollutant that has a great threat to environment. Among the processes available for the removal of ammoniacal nitrogen, one process is a combination of partial nitrification and anaerobic ammonium oxidation (anammox) process. It requires aerobic ammonium-oxidising bacteria (AOB) and anaerobic ammonium-oxidising bacteria (AnAOB). This paper presents the feasibility of enriching the AOB and AnAOB in 100-mL and 2.5-L batch reactors from fresh and mined MSW and leachate under aerobic and anaerobic conditions with varying feed-to-seed ratio. The AOB and AnAOB activity was monitored by measuring the intermediates such as hydroxylamine and hydrazine along with variations in ammoniacal nitrogen, nitrite nitrogen, and nitrate nitrogen concentrations in the reactor contents. The formation of intermediates such as hydroxylamine and hydrazine and ammoniacal nitrogen transformation data confirmed the enrichment of AOB and AnAOB. Further, AOB and AnAOB were validated by most probable number test and scanning electron microscopy analysis, respectively. DNA extraction, polymerase chain reaction amplification, and sequencing analysis authenticated the AnAOB as Candidatus Brocadia anammoxidans.
Article
Leaking sewer infrastructure contributes nonpoint nitrogen pollution to groundwater and surface water in urban watersheds. However, these inputs are poorly quantified in watershed budgets, potentially underestimating pollutant loadings. In this study, we used inverse methods to constrain dissolved inorganic nitrogen (DIN) inputs from sewage to Nine Mile Run (NMR), an urban watershed (1570 ha) in Pittsburgh, Pennsylvania (USA) characterized by extensive impervious surface cover (38%). Water samples were collected biweekly over two years and intensive sampling was conducted during one summer storm. A nitrogen budget for the NMR watershed was constructed, ultimately inverted, and sewage DIN inputs constrained using Monte Carlo simulation. Results reveal substantial DIN contributions from sewage ranging from 6 to 14 kg ha–1 yr–1. When conservative estimates of DIN from sewage are included in input calculations, DIN retention in NMR is comparable to high rates observed in other suburban/urban nutrient budgets (84%). These results suggest a pervasive influence of leaking sewers during baseflow conditions and indicate that sewage-sourced DIN is not limited to sewer overflow events. Further, they highlight the importance of sewage inputs to DIN budgets in urban streams, particularly as sewer systems age across the U.S.
Article
In today's context of waste management, landfilling of Municipal Solid Waste (MSW) is considered to be one of the standard practices worldwide. Leachate generated from municipal landfills has become a great threat to the surroundings as it contains high concentration of organics, ammonia and other toxic pollutants. Emphasis has to be placed on the removal of ammonia nitrogen in particular, derived from the nitrogen content of the MSW and it is a long term pollution problem in landfills which determines when the landfill can be considered stable. Several biological processes are available for the removal of ammonia but novel processes such as the Single Reactor System for High Activity Ammonia Removal over Nitrite (SHARON) and Anaerobic Ammonium Oxidation (ANAMMOX) process have great potential and several advantages over conventional processes. The combined SHARON-ANAMMOX process for municipal landfill leachate treatment is a new, innovative and significant approach that requires more research to identify and solve critical issues. This review addresses the operational parameters, microbiology, biochemistry and application of both the processes to remove ammonia from leachate.
Article
Full-text available
A two-stage non-conventional bench scale biological treatment system was investigated for the treatment of the wastewater laden with ammonium nitrate. The first stage which consisted of a fixed film anoxic reactor effected denitrification of nitrate ion, while the second stage consisting of a pond effected ammonia removal. Dissimilatory denitrification requires external carbon source as an electron donor. Methanol was used as electron donor in this system. The system exhibited substantial nitrate and ammonia removal. The influent nitrate-N concentration which was on average 193.87 ± 12.68 mg/l was reduced to 5.86 ± 4.86 mg/l in the denitrification unit. There was only a marginal reduction of ammonia in the denitrification unit and most of the ammonia-N was removed in the pond. The ammonia-N was reduced from an average value of 104.87 ± 3.49 mg/l at denitrification unit inlet to 33.37 ± 8.12 mg/l at the pond outlet. There was no corresponding increase in the nitrite or nitrate concentration in proportion to ammonia reduction in the pond. The average nitrate concentration in the pond outlet was 2.4 ± 0.93 mg/l. Microbiological investigation of the system revealed the presence of significant populations of denitrifying organisms in the first stage, and denitrifying, nitrifying and algal populations in the second stage. The system also sustained wastewater of pH as low as 3.87 and appears to be very promising for larger scale industrial wastewater treatment.
Article
Full-text available
A newly discovered process by which ammonium is converted to dinitrogen gas under anaerobic conditions (the Anammox process) has now been examined in detail. In order to confirm the biological nature of this process, anaerobic batch culture experiments were used. All of the ammonium provided in the medium was oxidized within 9 days. In control experiments with autoclaved or raw wastewater, without added sludge or with added sterilized (either autoclaved or gamma irradiated) sludge, no changes in the ammonium and nitrate concentrations were observed. Chemical reactions could therefore not be responsible for the ammonium conversion. The addition of chloramphenicol, ampicillin, 2,4-dinitrophenol, carbonyl cyanide m-chlorophenyl-hydrazone (CCCP), and mercuric chloride (HgIICl2) completely inhibited the activity of the ammonium-oxidizing sludge. Furthermore, the rate of ammonium oxidation was proportional to the initial amount of sludge used. It was therefore concluded that anaerobic ammonium oxidation was a microbiological process. As the experiments were carried out in an oxygen-free atmosphere, the conversion of ammonium to dinitrogen gas did not even require a trace of O2. That the end product of the reaction was nitrogen gas has been confirmed by using 15NH4+ and 14NO3-. The dominant product was 14-15N2. Only 1.7% of the total labelled nitrogen gas produced was 15-15N2. It is therefore proposed that the N2 produced by the Anammox process is formed from equimolar amounts of NH4+ and NO3-.
Article
Full-text available
With the increased use of chemical fertilizers in agriculture, many densely populated countries face environmental problems associated with high ammonia emissions. The process of anaerobic ammonia oxidation ('anammox') is one of the most innovative technological advances in the removal of ammonia nitrogen from waste water. This new process combines ammonia and nitrite directly into dinitrogen gas. Until now, bacteria capable of anaerobically oxidizing ammonia had never been found and were known as "lithotrophs missing from nature". Here we report the discovery of this missing lithotroph and its identification as a new, autotrophic member of the order Planctomycetales, one of the major distinct divisions of the Bacteria. The new planctomycete grows extremely slowly, dividing only once every two weeks. At present, it cannot be cultivated by conventional microbiological techniques. The identification of this bacterium as the one responsible for anaerobic oxidation of ammonia makes an important contribution to the problem of unculturability.
Article
Full-text available
In the global nitrogen cycle, bacterial denitrification is recognized as the only quantitatively important process that converts fixed nitrogen to atmospheric nitrogen gas, N2, thereby influencing many aspects of ecosystem function and global biogeochemistry. However, we have found that a process novel to the marine nitrogen cycle, anaerobic oxidation of ammonium coupled to nitrate reduction, contributes substantially to N2 production in marine sediments. Incubations with 15N-labeled nitrate or ammonium demonstrated that during this process, N2 is formed through one-to-one pairing of nitrogen from nitrate and ammonium, which clearly separates the process from denitrification. Nitrite, which accumulated transiently, was likely the oxidant for ammonium, and the process is thus similar to the anammox process known from wastewater bioreactors. Anaerobic ammonium oxidation accounted for 24 and 67% of the total N2 production at two typical continental shelf sites, whereas it was detectable but insignificant relative to denitrification in a eutrophic coastal bay. However, rates of anaerobic ammonium oxidation were higher in the coastal sediment than at the deepest site and the variability in the relative contribution to N2 production between sites was related to large differences in rates of denitrification. Thus, the relative importance of anaerobic ammonium oxidation and denitrification in N2 production appears to be regulated by the availability of their reduced substrates. By shunting nitrogen directly from ammonium to N2, anaerobic ammonium oxidation promotes the removal of fixed nitrogen in the oceans. The process can explain ammonium deficiencies in anoxic waters and sediments, and it may contribute significantly to oceanic nitrogen budgets.
Article
In this study a novel hydroxylamine oxidoreductase (HAO) was purified and characterized from an anaerobic ammonium-oxidizing (Anammox) enrichment culture. The enzyme, which constituted about 9% of the protein mass in the soluble fraction of the cell extract, was able to oxidize hydroxylamine and hydrazine. When phenazine methosulfate and methylthiazolyltetrazolium bromide were used as electron acceptors, a V(max) [21 and 1.1 micromol min(-)(1) (mg of protein)(-)(1)] and K(m) (26 and 18 microM) for hydroxylamine and hydrazine were determined, respectively. The hydroxylamine oxidoreductase is a trimer and contains about 26 hemes per 183 kDa. As deduced from UV/vis spectra, hydroxylamine reduced more and different cytochromes than hydrazine. The dithionite-reduced spectrum showed an unusual 468 nm peak. Inhibition experiments with H(2)O(2) showed that hydroxylamine bound to this P-468 cytochrome, which is assumed to be the putative substrate binding site. Cyanide and hydrazine inhibited the oxidation of hydroxylamine. The amino acid sequences of several peptide fragments of HAO from Anammox showed a clear difference with the deduced amino acid sequence of HAO from the aerobic ammonia-oxidizing bacterium Nitrosomonas europaea. In EPR spectra of the Anammox HAO, two g-values (g(z)() = 2.37 and 2.42) were observed, which were not present in HAO of N. europaea.
Article
The organisation of cells of the planctomycete species Pirellula marina, Isosphaera pallida, Gemmata obscuriglobus, Planctomyces maris and "Candidatus Brocadia anammoxidans" was investigated based on ultrastructure derived from thin-sections of cryosubstituted cells, freeze-fracture replicas, and in the case of Gemmata obscuriglobus and Pirellula marina, computer-aided 3-D reconstructions from serial sections of cryosubstituted cells. All planctomycete cells display a peripheral ribosome-free region, termed here the paryphoplasm, surrounding the perimeter of the cell, and an interior region including any nucleoid regions as well as ribosome-like particles, bounded by a single intracytoplasmic membrane (ICM), and termed the pirellulosome in Pirellula species. Immunogold labelling and RNase-gold cytochemistry indicates that in planctomycetes all the cell DNA is contained wholly within the interior region bounded by the ICM, and the paryphoplasm contains no DNA but at least some of the cell's RNA. The ICM in Isosphaera pallida and Planctomyces maris is invaginated such that the paryphoplasm forms a major portion of the cell interior in sections, but in other planctomycetes it remains as a peripheral zone. In the anaerobic ammonium-oxidising ("anammox" process) chemoautotroph "Candidatus Brocadia anammoxidans" the interior region bounded by ICM contains a further internal single-membrane-bounded region, the anammoxosome. In Gemmata obscuriglobus, the interior ICM-bounded region contains the nuclear body, a double-membrane-bounded region containing the cell's nucleoid and all genomic DNA in addition to some RNA. Shared features of cell compartmentalisation in different planctomycetes are consistent with the monophyletic nature of the planctomycetes as a distinct division of the Bacteria. The shared organisational plan for the planctomycete cell constitutes a new type not known in cells of other bacteria.
Article
The microbiology and the feasibility of a new, single-stage, reactor for completely autotrophic ammonia removal were investigated. The reactor was started anoxically after inoculation with biomass from a reactor performing anaerobic ammonia oxidation (Anammox). Subsequently, oxygen was supplied to the reactor and a nitrifying population developed. Oxygen was kept as the limiting factor. The development of a nitrifying population was monitored by Fluorescence In Situ Hybridization and off-line activity measurements. These methods also showed that during steady state, anaerobic ammonium-oxidizing bacteria remained present and active. In the reactor, no aerobic nitrite-oxidizers were detected. The denitrifying potential of the biomass was below the detection limit. Ammonia was mainly converted to N2 (85%) and the remainder (15%) was recovered as NO3-. N2O production was negligible (less than 0.1%). Addition of an external carbon source was not needed to realize the autotrophic denitrification to N2.
Article
Lipid membranes are essential to the functioning of cells, enabling the existence of concentration gradients of ions and metabolites. Microbial membrane lipids can contain three-, five-, six- and even seven-membered aliphatic rings, but four-membered aliphatic cyclobutane rings have never been observed. Here we report the discovery of cyclobutane rings in the dominant membrane lipids of two anaerobic ammonium-oxidizing (anammox) bacteria. These lipids contain up to five linearly fused cyclobutane moieties with cis ring junctions. Such 'ladderane' molecules are unprecedented in nature but are known as promising building blocks in optoelectronics. The ladderane lipids occur in the membrane of the anammoxosome, the dedicated intracytoplasmic compartment where anammox catabolism takes place. They give rise to an exceptionally dense membrane, a tight barrier against diffusion. We propose that such a membrane is required to maintain concentration gradients during the exceptionally slow anammox metabolism and to protect the remainder of the cell from the toxic anammox intermediates. Our results further illustrate that microbial membrane lipid structures are far more diverse than previously recognized.
  • A A Van De Graaf
  • P De Bruijn
  • L A Robertson
  • M S M Jetten
  • J G Kuenen
van de Graaf, A. A., de Bruijn, P., Robertson, L. A., Jetten, M. S. M. and Kuenen, J. G., Microbiology, 1997, 143, 2415-2421.
  • E Broda
Broda, E., Z. Allgem. Mikrobiol., 1977, 17, 491-493.
  • J Schalk
  • S De Vries
  • J G Kuenen
  • M S M Jetten
Schalk, J., De Vries, S., Kuenen, J. G. and Jetten, M. S. M., Biochemistry, 2000, 39, 5405-5412.
  • J S S Damste
Damste, J. S. S. et al., Nature, 2002, 419, 708-712.
India and Geetha Shivaraman is in the Department of Chemistry
  • N Shivaraman
N. Shivaraman*, † was formerly at National Environmental Engineering Research Institute, Nagpur 440 020, India and Geetha Shivaraman is in the Department of Chemistry, L.A.D. College for Women, Nagpur 440 010, India *Address for correspondence: Plot 9, Narkesari Layout (East), Jaiprakashnagar, Nagpur 440 025, India † For correspondence. e-mail: rashri@nagpur.dot.net.in