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The invention of microorganism’s involvement in carbonate precipitation, has lead the exploration of this process in the field of construction engineering. Biocement is a product innovation from developing bioprocess technology called biocementation. Biocement refers to a CaCO3 deposit that formed due to microorganism activity in the system rich of calcium ion. The primary role of microorganism in carbonate precipitation is mainly due to their ability to create an alkaline environment (high pH and DIC increase) through their various physiological activities. Three main groups of microorganism that can induce the carbonate precipitation: (i) photosynthetic microorganism such as cyanobacteria and microalgae; (ii) sulphate reducing bacteria; and (iii) some species of microorganism involved in nitrogen cycle. Microalgae are photosynthetic microorganism and utilize urea using urease or urea amidolyase enzyme, based on that it is possible to use microalgae as media to produce biocement through biocementation. This paper overviews biocement in general, biocementation, type of microorganism and their pathways in inducing carbonate precipitation and the prospect of microalgae to be used in biocement production.
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Research Article Open Access
Bioprocessing & Biotechniques
Ariyanti et al., J Bioproces Biotechniq 2012, 2:1
http://dx.doi.org/10.4172/2155-9821.1000111
Volume 2 • Issue 1 • 1000111
J Bioproces Biotechniq
ISSN:2155-9821 JBPBT, an open access journal
Keywords: Biocement; Biocementation; Microalgae; CaCO3 precipi-
tation
Introduction
Construction engineering consumes a large amount of materials
from non-renewable resources, which most of the materials contrib-
ute CO2 emission to the air at their production or application stage.
Technology development related to the construction material and their
production is necessary, in order to maintain the sustainability and to
reduce the production of CO2 emission. e evidence of microorgan-
ism involvement in carbonate precipitation, has lead the development
of bioprocess technology in the eld of construction material [1,2].
e precipitation of calcium carbonate (CaCO3) may be performed
due to microorganism activity and it produces massive limestone or
small crystal forms [3]. ese deposit of calcium carbonate known as
biocement or microbial induced carbonate precipitation (MICP) [3,4].
Biocement has many advantages compared to an ordinary cement,
such as: the production process is slightly dierent with sandstone pro-
duction, biocement need a much shorter time; it is suitable for in-situ
process; raw material of biocement are produced at low temperature,
more ecient compared to an ordinary cement which used tempera-
ture up to 1500C in production process; biocement can be used as eco-
construction material since it consume less energy and less CO2 emis-
sion in the production process rather than other ordinary cement [3,5].
Recently, research and study of biocement production through bio-
cementation still focused to the nitrogen cycle mechanism using urease
enzyme producing bacteria [3-7]. While research using microalgae as
media for biocementation still lack in literature, in fact microalgae have
a great potency for the objective of biocementation. Overview of bio-
cement, biocementation, type of microorganism, mechanism type and
feasibility of microalgae as media for biocement production will briey
described throughout this paper.
Microbial Induced Carbonate Precipitation (MCIP)
Calcium carbonate (CaCO3) precipitation is a common phenome-
non found in nature such as marine water, freshwater, and soils [1,6,8].
is precipitation is governed by four key factors: (i) the calcium (Ca2+)
concentration, (ii) the concentration of dissolved inorganic carbon
(DIC), (iii) the pH (pK2 (CO) = 10.3 at 25°C) and (iv) the availabil-
ity of nucleation sites [1,9]. Numerous species of microorganism have
been detected previously and assumed to be associated with natural
carbonate precipitates from diverse environments. e primary role of
microorganism in carbonate precipitation is mainly due to their abil-
ity to create an alkaline environment (high pH and [DIC] increase)
through their various physiological activities [1,6].
ere are three main groups of microorganism that can induce
the carbonate precipitation: (i) photosynthetic microorganism such as
cyanobacteria and microalgae; (ii) sulphate reducing bacteria; and (iii)
some species of microorganism involved in nitrogen cycle [1,6,7]. e
most common MCIP phenomena appeared in aquatic environments is
caused by photosynthetic microorganisms [7,10]. Photosynthetic mi-
croorganisms use CO2 in their metabolic process (equation 1) which
is in equilibrium with HCO3- and CO3
2- as described in equation 2.
Carbon dioxide consumed by photosynthetic microorganisms shi the
equilibrium and resulting the increment of pH (equation 3) [7]. When
this reaction occurs in the present of calcium ion in the system, calcium
carbonate is produced as described at chemical reaction in equation 4
[6].
CO2+ H2O  (CH2O) + O2 (1)
2HCO3- CO2 + CO3
2- + H2O (2)
CO3
2- + H2O HCO3-+ OH- (3)
Ca2+ + HCO3-+ OH- CaCO3+ 2H2O (4)
*Corresponding author: Dessy Ariyanti, Department of Chemical Engineering,
Faculty of Engineering, Diponegoro University, Prof Soedarto, SH Kampus Tembal-
ang, Semarang, Indonesia, Tel: +62-24-7460058; Fax: +62-24-76480675; E-mail:
dessy@undip.ac.id
Received December 24, 2011; Accepted January 19, 2012; Published January
22, 2012
Citation: Ariyanti D, Handayani NA, Hadiyanto (2012) Feasibility of Using
Microalgae for Biocement Production through Biocementation. J Bioprocess
Biotechniq 2:111 doi: 10.4172/2155-9821.1000111
Copyright: © 2012 Ariyanti D, et al. This is an open-access article distributed under
the terms of the Creative Commons Attribution License, which permits unrestricted
use, distribution, and reproduction in any medium, provided the original author and
source are credited.
Abstract
The invention of microorganism’s involvement in carbonate precipitation, has lead the exploration of this process
in the eld of construction engineering. Biocement is a product innovation from developing bioprocess technology
called biocementation. Biocement refers to a CaCO3 deposit that formed due to microorganism activity in the system
rich of calcium ion. The primary role of microorganism in carbonate precipitation is mainly due to their ability to create
an alkaline environment (high pH and DIC increase) through their various physiological activities. Three main groups
of microorganism that can induce the carbonate precipitation: (i) photosynthetic microorganism such as cyanobacteria
and microalgae; (ii) sulphate reducing bacteria; and (iii) some species of microorganism involved in nitrogen cycle.
Microalgae are photosynthetic microorganism and utilize urea using urease or urea amidolyase enzyme, based on
that it is possible to use microalgae as media to produce biocement through biocementation. This paper overviews
biocement in general, biocementation, type of microorganism and their pathways in inducing carbonate precipitation
and the prospect of microalgae to be used in biocement production.
Feasibility of Using Microalgae for Biocement Production through
Biocementation
Dessy Ariyanti*, Noer Abyor Handayani and Hadiyanto
Department of Chemical Engineering, Faculty of Engineering, Diponegoro University, Prof Soedarto, SH Kampus Tembalang, Semarang, Indonesia
Citation: Ariyanti D, Handayani NA, Hadiyanto (2012) Feasibility of Using Microalgae for Biocement Production through Biocementation. J Bioprocess
Biotechniq 2:111 doi: 10.4172/2155-9821.1000111
Page 2 of 4
J Bioproces Biotechniq
ISSN:2155-9821 JBPBT, an open access journal Volume 2 • Issue 1 • 1000111
e precipitation of calcite (CaCO3) can also be induced by het-
erotrophic organism. is microorganism produces carbonate or bi-
carbonate and modied the system so that the carbonate precipitation
may occur [1]. Abiotic dissolution of gypsum (CaSO4.H2O) (equation
5) causes system rich of sulphate and calcium ion. In the presence of
organic matter and the absence of oxygen, sulphate reducing bacteria
(SRB) can reduce sulphate to H2S and HCO3- as described in equation
6 [1,7]. When the H2S degasses from the environment, pH of system
will increase and the precipitation of calcium carbonate will occur [1].
CaSO4.H2O  Ca2++ SO4
2-+ 2H2O (5)
2(CH2O) + SO4
2- HS- + HCO3
-+ CO2 + H2O (6)
Currently, urease enzyme activity in most of microorganism me-
tabolism process has been used as a tool to induce the precipitation of
calcium carbonate [11,12]. e hydrolysis of urea by urease enzyme in
heterotrophic microorganism will produce carbonate ion and ammo-
nium. is mechanism will result system with higher pH and rich of
carbonate ion [12]. One mole of urea hydrolysed intracellularly to one
mole ammonia and one mole carbamate (equation 7), which spontane-
ously hydrolysed to one mole ammonia and one mole carbonic acid
(equation 8). Ammonia and carbamate subsequently equilibrate in wa-
ter to form bicarbonate and 2 moles of ammonium and hydroxide ions
as described in equation 9 and 10 [2].
CO(NH2)2 +H2O H2COOH + NH3 (7)
NH2COOH + H2O  NH3 + H2CO3 (8)
2NH3 + 2H2O  2NH4
+ + 2OH- (9)
2OH- + H2CO3  CO3
2- + 2H2O (10)
Total reaction:
CO(NH2)2 + 2H2O  2NH4
+ + CO3
2- (11)
e presence of calcium ion in the system will lead to the calci-
um carbonate precipitation once a certain level of supersaturation is
reached. e calcium carbonate precipitation mechanism induced by
urease enzyme activity illustrated in gure 1.
Calcium ions in the solution are attracted to microorganism cell
wall due to the negative charge of the latter. Aer the addition of urea to
the system, microorganism convert urea to dissolved inorganic carbon
(DIC) and ammonium (AMM) and released it to the environment (A).
e presence of calcium ion cause the supersaturation condition and
precipitation of calcium carbonate in microorganism cell wall (B). Af-
ter a while, the whole cell becomes encapsulated by calcium carbonate
precipitate (C). As whole cell encapsulated, nutrient transfer becomes
limited and resulting in cell death. Image (D) shows the imprints of
microorganism cell involved in carbonate precipitation [6].
Biocementation
Biocementation is a process to produce binding material (bioce-
ment) based on microbial induced carbonate precipitation (MICP)
mechanism. is process can be applied in many elds such as con-
struction, petroleum, erosion control, and environment. Application
in construction eld include wall and building coating method, soil
strengthening and stabilizing, and sand stabilizing in earthquake prone
zone [2].
In application, the precipitation of calcium carbonate (biocement)
is combined with other supporting material such as sand. e patented
method of producing biocement can be seen in gure 2 [7,4].
Biocementation illustrated in gure 2 uses heterotroph bacteria
Bacillus pasteurii with urea hydrolysis mechanism. e cementation
process occurs in pipe columns lled with commercial sand contained
silica. Urea/calcium solution and bacteria solution were mixed imme-
diately and put in the pressurized vessel to be injected to the sand core
in pipe column for several time until the sand core fully saturated. Bio-
cementation takes about 24 hours to complete the reaction, aer that
the biocement were dried in temperature of 60˚C [7].
Biocementation were also developed in the process of biological
mortar production, crack in concrete remediation and production of
bacterial concrete [2,9]. Table 1 shows overview of various construc-
tion materials made from biocementation.
In general, mortar refers to “ready to use” binder material con-
tained a binder, and sand or aggregate. Biological mortar consists of
three main components such as limestone powder, nutrient and bacte-
rial paste [2]. Biocementation applied in concrete ri remediation and
the production of bacterial concrete has been investigated (Santhosh
et al. [13]). Specimen of crack in concrete lled with biocement shows
the signicant increment of strength and stiness value compared with
specimen without biocement [13].
eoretically, calcium carbonate precipitation occur in nature fol-
lowing several process such as: (i) abiotic chemical precipitation from
saturated solution due to evaporation, temperature increase and/or
pressure decrease; (ii) production of external and internal skeleton by
eukaryotes; (iii) CO2 pressure derivation under eect of autotrophic
processes (photosynthesis, methanogenesis); (iv) fungal mediation;
(A) (B) (C) (D)
Ca
Ca
Ca
Ca
Ca
Ca
Ca
DIC
UREA
AMM
2 µm
Figure 1: Illustration of calcium carbonate precipitation mechanism induced by urease enzyme activity in microorganism [6].
Citation: Ariyanti D, Handayani NA, Hadiyanto (2012) Feasibility of Using Microalgae for Biocement Production through Biocementation. J Bioprocess
Biotechniq 2:111 doi: 10.4172/2155-9821.1000111
Page 3 of 4
J Bioproces Biotechniq
ISSN:2155-9821 JBPBT, an open access journal Volume 2 • Issue 1 • 1000111
(v) heterotrophic bacterial mediation [1]. Most of the mentioned pro-
cesses above are mediated by microorganism. Both photosynthetic and
heterotrophic microorganisms have natural ability to induce the pre-
cipitation of calcium carbonate. ere are large amount of microor-
ganism in many type of species spreads throughout the world. Table 2
shows several species which is already investigated as media in calcium
carbonate precipitation [6].
In biocementation, microorganism that used as media should meet
the specic requirement, since the process create a high pH in the en-
vironment and involving high concentration of calcium ion. For ex-
ample, in biocementation based on urea hydrolysis, the process will
produce high concentration of ammonium and not all type of micro-
organism can survive in such condition. Based on that, the selected of
microorganism should meet the criteria such as: (i) have a high urease
enzyme activity; (ii) ammonium and calcium ion tolerable; (iii) not
pathogenic [7].
Feasibility of Using Microalgae in Biocementation
Microalgae are a promising media to be used in biocementation,
due to its photosynthetic metabolism. Algae’s species like Spirulina,
Arthrospira plantensis (Cyanophyta), Chlorella vulgaris (Chlorophyta),
Dunaliella salina, Haematococcus pluvialis, Muriellopsis sp., Porphyrid-
ium cruentum (Rhodophyta) basically are autotrophic microorganisms
that live through photosynthetic process [14-16].
Experiment of nine green algae, a diatom and three cyanobacteria
were shown to precipitate CaCO3 in batch culture, where grown in the
light in a hard water medium containing 68 mg L−1 soluble calcium.
e composition of the medium was based on that found in natural
marine hard water where precipitation of CaCO3 within algal biolms
occurred. Deposition occurred as a direct result of photosynthesis
which caused an increase in the pH of the medium. Once a critical pH
had been reached, typically approximately pH 9.0, precipitation be-
gan evidenced by a fall in the concentration of soluble calcium in the
medium [17]. In other experiment, Synechococcus cyanobacteria, the
eukaryotic Mychonastes sp., and Chlorella sp., were found to induce the
precipitation of CaCO3 [18]. In all experiments the precipitation pro-
cess developed in three stages: (1) a pH-dri period, (2) the actual pre-
cipitation reaction, and (3) an equilibration phase. e time intervals
of the stages as well as the concentration changes found in the work
were comparable to the results of other experimental studies on CaCO3
precipitation by algae as shown in table 3 and gure 3 [18].
Several types of microalgae also use urea hydrolysis mechanism to
full the needs of nitrogen. For example, Chorella sp utilizes urea as a
nitrogen source; urea is hydrolysed by urease or urea amidolyase en-
zyme to produce ammonia and bicarbonate [19]. e activity of urease
enzyme also can induce the precipitation of calcium carbonate [11,12].
Figure 2: Injection method of cementation liquid (contain calcium/urea solu-
tion and bacterial cell) in biocementation [4,7].
(a)
(b)
Acc.v Spot Magn Det WD Exp
20.0kV 4.0 250x SE 10.2 599 EAWAG
Acc.v Spot Magn WD
12.0kV 2.0 12000x 100 FAWAG
10µm
2µm
Figure 3: (a) SEM photograph of carbonate precipitates in presence of eu-
karyotic picoplankton, holes in the carbonate structure correspond to pico-
plankton cells and (b) picocyanobacteria [18].
Application Microorganism Metabolism Solution Reference
Biological
mortar
Bacillus cereus oxidative
deamination of
amino acids
Growth media
(peptone, extract
yeast, KNO3, NaCl)
+ CaCl2.2H2O, Acti-
cal, Natamycine
[2]
Crack in
concrete
remediation
Bacillus pasteurii
Bacillus sphaeri-
cus
Hydrolysis of
urea
Hydrolysis of
urea
Nutrient broth, urea,
CaCl2.2H2O, NH4Cl,
NaHCO3
Extract yeast, urea,
CaCl2.2H2O
[13]
[9]
Bacterial
concrete
Bacillus pasteurii Hydrolysis of
urea
Nutrient broth, urea,
CaCl2.2H2O, NH4Cl,
NaHCO3
[13]
Table 1: Overview of various construction materials made from biocementation.
Citation: Ariyanti D, Handayani NA, Hadiyanto (2012) Feasibility of Using Microalgae for Biocement Production through Biocementation. J Bioprocess
Biotechniq 2:111 doi: 10.4172/2155-9821.1000111
Page 4 of 4
J Bioproces Biotechniq
ISSN:2155-9821 JBPBT, an open access journal Volume 2 • Issue 1 • 1000111
ere are some advantages of using microalgae as media for bioce-
ment production. Microalgae are type of renewable resources that eas-
ily cultivated rather than other type of microbe such as bacteria which
already proved to be used in biocementation, so that its availability as
raw material can be maintained properly. It’s easy to grow especially in
tropical area, where many non-agricultural landlls can be utilized as
a raceway pond for microalgae cultivation. Tropical country also has a
good temperature and water with high mineral contained which is very
suitable for microalgae cultivation [15]. Another advantage is that the
biocement production using microalgae can reduce the CO2 emission,
which produced in conventional cement production [5,3].
Based on table 3, the microalga is able to precipitate calcite very
eectively within a couple days [18], while using bacteria such as Spo-
rosarcina pasteurii is able to precipitate calcite under certain condition
within 24 hours. But yet the exact data of experiment and literature still
lack for the microalgae carbonate precipitation.
Future Challenge
Biocement is product innovation in material eld that can be pro-
duce naturally using microorganism such as bacteria and microalgae.
Microalgae have a great potential to be developed as media for bio-
cement production through biocementation. Microalgae metabolism
activity such as photosynthesize and hydrolysing urea can create the
alkaline environment (pH and DIC elevation), so that calcium carbon-
ate precipitation occurs in the presence of calcium ion in the system.
On the other side, microalgae also part of renewable resource that
is easily cultivated especially in tropical area, so that its availability as
raw material can be maintain properly. Further basic research needs to
be done, primary to the theme related to suitable type of microalgae,
mechanism used in biocement production through biocementation,
the kinetics of process, and also the optimum condition to produce
good quality of biocement.
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Type of microorganism System Chrystal type Reference
Photosynthetic organism
Synechococcus GL24
Chlorella
Meromictic lake
Lurcene Lake Calcite CaCO3)
Calcite (CaCO3)
[21]
[18]
Sulfate reducing bacteria
Isolate SRB LVform6 Anoxic hypersaline lagoon Dolomite (Ca(Mg) CO3) -
Nitrogen cycle
Bacillus pasteurii
Bacillus cereus
Urea degradation in synthetic medium
Ammonication and nitrate reduction
Calcite (CaCO3)
Calcite (CaCO3)
[10]
[1]
Table 2: Several species which already investigated as media in calcium carbonate precipitation [6].
Experiment Cell abundance [103cells.ml-1]Chlorophyll [μg.l-1] pH drift time [h] pH at Start of prec. Length of prec. [h] % of Ca2+ precipitation
Mychonastes sp. (1) 13.2 142 45 9.05 50 41
Mychonastes sp. (2) 22.9 448 18 9.20 30 34
Chlorella sp. (1) 6.85 222 25 9.00 10 26
Chlorella sp. (2) 8.71 379 11 8.95 4 29
Synechococcus (1) 33.4 130 40 8.95 40 13
Synechococcus (2) 94.1 324 30 9.05 8 32
Table 3: Precipitation experiments of CaCO3 induced by several types of algae [18].
... In geotechnical application, a cementation solution consisting of an equimolar solution of urea and a calcium source is supplied, which, through the metabolic activity of the bioagent, is converted into calcium carbonate, which binds the soil particles [3]. 7th International Conference on Advances in Civil Engineering (ICACE2024) [12][13][14] December 2024 CUET, Chattogram, Bangladesh https://icace2024.cuet.ac.bd ...
... This suggests its use in soil stabilization should be equally feasible. The utilization of cyanobacteria is even more fitting for developing countries as the cost of culture is low and can be easily cultivated without rigorous control [14]. Therefore, the prospect of utilizing cyanobacteria as a bio-agent for MICP holds promise. ...
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... Biocement refers to calcium carbonate (CaCO 3 ) deposits formed as a result of microbial activity in the systems that contain rich supplements in calcium ions. The major role of microorganisms in the precipitation of carbonate is due to their capability to produce an alkaline environment by many physiological actions (Ariyanti, 2012). The effects of different nitrogen sources and different concentrations of sodium bicarbonate and carbon dioxide were investigated on C. vulgaris in terms of biomass concentration, biocement sedimentation rate, and productivity. ...
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Environmental pollution is a big challenge that has been faced by humans in contemporary life. In this context, fossil fuel, cement production, and plastic waste pose a direct threat to the environment and biodiversity. One of the prominent solutions is the use of renewable sources, and different organisms to valorize wastes into green energy and bioplastics such as polylactic acid. Chlorella vulgaris, a microalgae, is a promising candidate to resolve these issues due to its ease of cultivation, fast growth, carbon dioxide uptake, and oxygen production during its growth on wastewater along with biofuels, and other productions. Thus, in this article, we focused on the potential of Chlorella vulgaris to be used in wastewater treatment, biohydrogen, biocement, biopolymer, food additives, and preservation, biodiesel which is seen to be the most promising for industrial scale, and related biorefineries with the most recent applications with a brief review of Chlorella and polylactic acid market size to realize the technical/nontechnical reasons behind the cost and obstacles that hinder the industrial production for the mentioned applications. We believe that our findings are important for those who are interested in scientific/financial research about microalgae.
... Microbially induced calcium carbonate precipitation Induced Calcium Carbonate Precipitation (MICP), which exploits the microbial metabolic processes for bio-cementation to enhance the durability of construction materials, has drawn attention not only in soil stabilization [1][2][3][4][5][6][7][8][9][10][11] and building construction [12][13][14][15][16][17][18][19][20][21][22] but also in wind-induced desertification [23][24][25][26], stone artwork conservation [27], and even subsurface-related applications [28,29]. Microorganisms engaged in the nitrogen cycle, sulphate-reducing bacteria, and photosynthetic microorganisms have all been reported to induce calcium carbonate [30,31]. Although the bio-cementation process produces ammonia gas that is undesirable [32], in comparison to the traditional methods, which make use of Portland cement, it offers a variety of benefits, including the following: ...
... However, additional research is required to investigate the impact of these different growth media on other characteristics of concrete, such as its cost, strength, shrinkage, resistance to corrosion, and workability. Another investigation on the viability of S. pasteurii under extreme conditions (30,45, and 55 • C) and pH (12.5-13.6) conditions demonstrated that exposing the bacteria to extreme temperatures (specifically 55 • C for 4 h) and extreme pH (specifically 13.6 for 4 h) led to the most significant decrease in both the concentration of viable cells and the initial rate of ammonia production through urea hydrolysis [114]. ...
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With the development of bioinspired green solutions for sustainable construction over the past two decades, bio-cementation, which exploits the naturally occurring phenomenon of calcium carbonate precipitation in different environments, has drawn a lot of attention in both building construction and soil stabilization. Various types of microorganisms, along with specific enzymes derived from these microorganisms, have been utilized to harness the benefits of bio-cementation. Different application methods for incorporating this mechanism into the production process of the construction material, as well as a variety of experimental techniques for characterizing the outcomes of bio-cementation, have been developed and tested. Despite the fact that the success of bio-cementation as a sustainable method for construction has been demonstrated in a significant body of scientific literature at the laboratory scale, the expansion of this strategy to construction sites and field application remains a pending subject. The issue may be attributed to two primary challenges. Firstly, the complexity of the bio-cementation phenomenon is influenced by a variety of factors. Secondly, the extensive body of scientific literature examines various types of microorganisms under different conditions, leading to a wide range of outcomes. Hence, this study aims to examine the recent advancements in utilizing the most commonly employed microorganism, Sporosarcina pasteurii, to emphasize the significance of influential factors identified in the literature, discuss the findings that have been brought to light, and outline future research directions toward scaling up the process.
... Algal cell surfaces and the extracellular polymeric substances in the microalgal biofilm provide substrates that facilitate the nucleation and precipitation of CaCO 3 (50). The formation of CaCO 3 in microalgal cultures, mediated by MICP, has been studied in several algal species, including N. oceanica IMET1 (18,19,24). Although many studies have investigated MICP within microalgae that form carbonate skeletons, coccolithophores (51,52), few have paired CaCO 3 formation with a lipid-rich alga that has the ability to grow under high CO 2 conditions. ...
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To combat the increasing levels of carbon dioxide (CO 2 ) released from the combustion of fossil fuels, microalgae have emerged as a promising strategy for biological carbon capture, utilization, and storage. This study used a marine microalgal strain, Nannochloropsis oceanica IMET1, which thrives in high CO 2 concentrations. A high-pH, high-alkalinity culture was designed for CO 2 capture through algal biomass production as well as permanent sequestration through calcium carbonate (CaCO 3 ) precipitation. This was accomplished by timed pH elevation and the addition of sodium bicarbonate to cultures of N. oceanica grown at lab scale (1 L) and pilot scale (500 L) with 10% and 5% CO 2 , respectively. Our data showed that 0.02 M NaHCO 3 promoted algal growth and that sparging cultures with ambient air after 12 days raised pH and created favorable CaCO 3 formation conditions. At the 1 L scale, we reached 1.52 g L ⁻¹ biomass after 12 days and an extra 9.3% CO 2 was captured in the form of CaCO 3 precipitates. At the 500 L pilot scale, an extra 60% CO 2 was captured (Day 40) with a maximum CO 2 capture rate of 63.2 g m ⁻² day ⁻¹ (Day 35). Bacterial communities associated with the microalgae were dominated by two novel Patescibacteria. Functional analysis revealed that genes for several plant growth-promotion traits (PGPTs) were enriched within this group. The microalgal-bacterial coculture system offers advantages for enhanced carbon mitigation through biomass production and simultaneous precipitation of recalcitrant CaCO 3 for long-term CO 2 storage. IMPORTANCE Capturing carbon dioxide (CO 2 ) released from fossil fuel combustion is of the utmost importance as the impacts of climate change continue to worsen. Microalgae can remove CO 2 through their natural photosynthetic pathways and are additionally able to convert CO 2 into a stable, recalcitrant form as calcium carbonate (CaCO 3 ). We demonstrate that microalgae-based carbon capture systems can be greatly improved with high pH and high alkalinity by providing optimal conditions for carbonate precipitation. Our results with the microalga, Nannochloropsis oceanica strain IMET1, show an extra 9.3% CO 2 captured as CaCO 3 at the 1 L scale and an extra 60% CO 2 captured at the 500 L (pilot) scale. Our optimized system provides a novel approach to capture CO 2 through two mechanisms: (i) as organic carbon within microalgal biomass and (ii) as inorganic carbon stored permanently in the form of CaCO 3.
... • Bioconcrete/Biocement: this is an alternative to the traditional concrete which was found to be unsustainable and negatively affects the environment. It was found that incorporating microalgae biomass into concrete during the mixing phase provides enhanced durability and strength (Ariyanti, 2012;Jebamalar and Iyer, 2016;Luhar et al., 2022;Yu et al., 2022). Species that show potential for Bioconcrete/Biocement production are Porphyridium cruentum, Spirulina, Arthrospira sp, Chlorella vulgaris, Dunaliella salina, Muriellopsis sp. and Haematococcus pluvialis (Ariyanti and Abyor Handayani, 2011;Srinivas et al., 2021). ...
... Within the building sector, especially via cement within which CaCO 3 is a pivotal chemical component, it is established that CaCO 3 contributes increasing the concrete's strength and its workability [86][87][88][89] . It also improves the concrete's particle packing while providing concrete with a spacer effect, and promotes self-compacting properties of concrete [90][91][92] . In addition, CaCO 3 reduces porosity and air void in concrete and adds to smoother surfaces 87 . ...
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This contribution reports, for the first time, on an entirely green bio-engineering approach for the biosynthesis of single phase crystalline 1-D nano-scaled calcite CaCO3. This was validated using H2O as the universal solvent and natural extract of Hyphaene thebaica fruit as an effective chelating agent. In this room temperature green process, CaCl2 and CO2 are used as the unique source of Ca and CO3 respectively in view of forming nano-scaled CaCO3 with a significant shape anisotropy and an elevated surface to volume ratio. In terms of novelty, and relatively to the reported scientific and patented literature in relation to the fabrication of CaCO3 by green nano-chemistry, the current cost effective room temperature green process can be singled out as per the following specificities: only water as universal solvent is used, No additional base or acid chemicals for pH control, No additional catalyst, No critical or supercritical CO2 usage conditions, Only natural extract of thebaica as a green effective chelating agent through its phytochemicals and proper enzematic compounds, room Temperature processing, atmospheric pressure processing, Nanoscaled size particles, and Nanoparticles with a significant shape anisotropy (1-D like nanoparticles). Beyond and in addition to the validation of the 1-D synthesis aspect, the bio-engineered CaCO3 exhibited a wide-ranging functionalities in terms of highly reflecting pigment, an effective nanofertilizer as well as a potential binder in cement industry.
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Bio-cement is an innovative material with the potential for replacement of conventional cement through microorganisms-influenced process. The major method uses bacterial, fungal, or algal activity to produce Microbial-Induced Calcium carbonate Precipitation (MICP). This review aims to understand the microbial aspect of bio-cement production explaining the process through MICP that is enhanced by ureolytic bacteria with a focus on Sporosarcina pasteurii through the provide urease. Bio-cement has many environmental advantages such as lower CO2 emission in comparison with common cement and opportunities to utilization of waste products. In construction, it is used in self-healing concrete, crack repair, and soil stabilization among others to demonstrate its flexibility in the construction industry due to its available solutions to many structural and geotechnical problems. The review also includes directions for basic, applied, and translational research, targeted genetic modifications for enhanced microbial performance, bio-cement, and more effective microbial strains, and the convergence of bio-cement with 3D printing. Even though bio-cement is an environmentally friendly approach used for soil stabilization, the negative impacts that surround the environment, for further research in making the bio-cement more bio-deteriorate and energy efficient.
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Bio-cement and bio-concrete are innovative solutions for sustainable construction, aiming to reduce environmental impact while maintaining the durability and versatility of building materials. Bio-cement is an eco-friendly alternative to traditional cement, produced through Microbially Induced Calcium Carbonate Precipitation (MICP), which mimics natural biomineralization processes. This method reduces CO2 emissions and enhances the strength and durability of construction materials. Bio-concrete incorporates bio-cement into concrete, creating a self-healing material. When cracks form in bio-concrete, dormant bacteria within the material become active in the presence of water, producing limestone to fill the cracks, extending the material’s lifespan and reducing the need for repairs. The environmental impact of traditional cement production is significant, with cement generation accounting for up to 8% of global carbon emissions. Creative solutions are needed to develop more sustainable construction materials, with some efforts using modern innovations to make concrete ultra-durable and others turning to science to create affordable bio-cement. The research demonstrates the potential of bio-cement to revolutionize sustainable building practices by offering a low-energy, low-emission alternative to traditional cement while also addressing environmental concerns. The findings suggest promising applications in various construction scenarios, including earthquake-prone areas, by enhancing material durability and longevity through self-repair mechanisms.
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This study investigated the potential use of microalgae as partial cement replacement to heal cracks in cement mortar. Microbially induced calcite (CaCO3) precipitation (MICP) from Arthrospira platensis (A. platensis) (UMACC162) was utilised for crack-healing applications. Microalgae was cultivated in Kosaric Media (KM) together with filtered cement water (FCW), and used as a cement replacement material. The microalgal species was further evaluated for its capacity and adaptability towards large-scale culturing. The results showed that A. platensis could adapt and survive in cement water solution and cement mortar, suggesting the potential for self-healing in cement mortar. Further, the cultured species grown in both conditions (KM and KM & FCW) were harvested and incorporated into the cement mortar as a partial cement replacement material at different levels of 5%, 10%, 20%, and 30% of cement weight. The cement mortars partially replaced with microalgae were cured in water for 28 days. Pre-cracks were induced in the cured mortar with the 75% of their ultimate load. It took just 14 days for the microalgae-incorporated mortar to heal the cracks. The specimens with microalgae cultured in FCW showed a better performance and recovered 59% of their strength, with a maximum healed crack width of 0.7 mm. In terms of water tightness and porosity, they are comparable to the control mortar. The compressive strength measurements indicated the formation of calcite aggregate (crystal) that sealed the surface cracks, which was confirmed by a microstructural analysis. The results also demonstrate that the incorporation of microalgae into cement produced a self-healing effect, providing a new direction for crack healing. Additionally, the investigation indicated that replacing cement with microalgae reduced CO2 emissions by as much as 30%, with a substitution of 30% of microalgae. Exploring microalgae as a cement replacement could reduce carbon emissions and improve the state of the environment. Graphical Abstract
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This paper has presented a mini review of previously published articles dealing with bio-cement production using enzyme-induced calcite precipitation (EICP) technique. EICP is a biological, sustainable, and natural way of producing calcite without the direct involvement of microorganisms from urea and calcium chloride using urease enzyme in water-based solution with minimum energy consumption and eco-friendly. Calcite is a renewable bio-material that acts as a binder to improve the mechanical properties of soils like strength, stiffness, and water permeability. EICP has many real applications such as fugitive duct control with low cost comparing with water application or pouring, self-healing cracked concretes, and upgrade or change the low-volume road surfaces that are difficult for road constructions. The crystal structure of finally produced calcium carbonate (CaCO 3), calcite is affected by the source of calcium ion; the calcite produced from calcium chloride has a rhombohedral crystal structure. The urease enzyme used for EICP applications could be produced in a laboratory-scale from different plant species, bacteria, some yeasts, fungi, tissues of humans, and invertebrates. Nevertheless, urease enzyme produced from jack beans has showed urease enzyme activity around 2700-3500U/g, and the tendency to replace the urease enzyme found in the global market. All urease enzymes have 12-nm size, and this smaller size makes EICP preferable for all types of soil or sands including fine and silt sands.
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Reef corals calcify faster in the presence of non-calcareous algae. Ratios of calcification to photosynthesis appear to be affected by the ratio of alkalinity to acidity, which controls how efficiently the protons from calcification convert bicarbonate to carbon dioxide. By forcing calcifiers to calcify faster, algal proliferation on nutrient-enriched reefs may adversely affect the reef-builders.
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A 1-year field study monitoring depth profiles of picoplankton and physicochemical data in the oligotrophic Lake Lucerne (Switzerland) showed that picocyanobacteria play an important role in the CaCO3 precipitation process. Laboratory experiments with Mychonastes and Chlorella, isolated from Lake Lucerne and Synechococcus using ion selective electrodes, scanning electron microscopy and X-ray powder diffraction clearly demonstrated the potential of picoplankton for fast and effective CaCO3 precipitation. The combination of a field study with laboratory experiments confirmed the previous reports of picocyanobacteria triggering the CaCO3 precipitation in hardwater oligotrophic lakes. Electron micrographs of particles from the water column often reveal the size and shape of picoplankton cells covered by calcite. In addition the results from the laboratory approach indicated that algae and bacteria induced different precipitation mechanisms. Experiments with Mychonastes and Chlorella produced crystalline calcite completely covering the cells. Experiments with the cyanobacteria Synechococcus, however, yielded amorphous, micritic CaCO3, indicating a different precipitation process.
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Extracts prepared from 10 bacteria-free algal cultures and 4 naturally occurring seaweeds were examined for urease and ATP-urea amidolyase (UAL-ase) activities. UAL-ase activity is confined to members of the classes Volvocales, Chlorococcales and Chaetophorales in the Chlorophyceae. Members of the Ulotrichales may possess either urease or UAL-ase. Ulva contains urease. All other algae, so far examined, which can grow with urea as nitrogen source contain urease but not UAL-ase.
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Nine green algae, a diatom and three cyanobacteria were shown to precipitate CaCO3 in batch culture, when grown in the light in a hard water medium containing 68 mg L−1 soluble calcium. The composition of the medium was based on that found in a natural hardwater marina where precipitation of CaCO3 within algal biofilms occurred. Deposition occurred as a direct result of photosynthesis which caused an increase in the pH of the medium. Once a critical pH had been reached, typically approximately pH 9.0, precipitation began evidenced by a fall in the concentration of soluble calcium in the medium. Certain characteristics of the precipitation process displayed by the diatom Navicula sp. were different to those of the other algae. All algae produced extracellular crystals of irregular morphology. Using a standardized protocol employing the green algae Chlorococcum sp. and Stigeoclonium variabile, the effects of various inhibitors of CaCO3 nucleation or growth of crystals were studied. Fifteen compounds were screened and assessed for their performance in this context. Most materials effectively delayed deposition of CaCO3, many decreased precipitation rates and all had a marked effect on crystal morphology. The most effective compound was HEDP (1-hydroxyethylene 1,1 diphosphonic acid), which inhibited precipitation completely at a concentration of 2.5 mg L−1 The use of such compounds to reduce the precipitation of calcium salts within algal biofilms in natural hard waters is discussed.
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Micro-organisms can have a devastating effect on building materials. They produce a range of organic and inorganic acids and enzymes, inducing solution and alteration of mineral phases. Biofilms alter the water exchange of the material and also mechanical effects add to the biodeterioration. One especially deleterious process in which bacteria are involved, is biogenic sulphuric acid corrosion in sewer systems. On the other hand, some types of bacteria can be used in engineering applications, for example for biological cleaning and bioconsolidation. Bacterially induced carbonate precipitation has been proposed as an environmentally friendly method to consolidate and protect decayed limestone or cementitious materials. The method relies on the bacterially induced formation of a compatible and highly coherent carbonate precipitate. Furthermore, the same principle can be applied for manual or autonomous remediation of cracks in concrete and the bacteria are in this case used as self healing agents. KeywordsBiodeterioration-Biodegradation-Bioconsolidation-Microorganisms-Concrete-Stone
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Evidence of microbial involvement in carbonate precipitation has led to the exploration of this process in the field of construction materials. One of the first patented applications concerned the protection of ornamental stone by means of a microbially deposited carbonate layer, i.e. biodeposition. The promising results of this technique encouraged different research groups to evaluate alternative approaches, each group commenting on the original patent and promoting its bacterial strain or method as the best performing. The goal of this review is to provide an in-depth comparison of these different approaches. Special attention was paid to the research background that could account for the choice of the microorganism and the metabolic pathway proposed. In addition, evaluation of the various methodologies allowed for a clear interpretation of the differences observed in effectiveness. Furthermore, recommendations to improve the in situ feasibility of the biodeposition method are postulated. In the second part of this paper, the use of microbially induced carbonates as a binder material, i.e. biocementation, is discussed. Bacteria have been added to concrete for the improvement of compressive strength and the remediation of cracks. Current studies are evaluating the potential of bacteria as self-healing agents for the autonomous decrease of permeability of concrete upon crack formation.
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Experiments show that the production of carbonate particles by heterotrophic bacteria follows different ways. In heterotrophy, the passive carbonatogenesis is generated by modifications of the medium that lead to the accumulation of carbonate and bicarbonate ions and to the precipitation of solid particles. It is induced by several metabolic pathways of the nitrogen cycle (ammonification of amino-acids, degradation of urea and uric acid, dissimilatory reduction of nitrates) and of the sulphur cycle (dissimilatory reduction of sulphates). The active carbonatogenesis is independent of the mentioned metabolic pathways. The carbonate particles are produced by ionic exchanges through the cell membrane following still poorly known mechanisms. In autotrophy, non-methylotrophic methanogenesis and cyanobacterial photosynthesis also may contribute to the precipitation of carbonates (autotrophic carbonates). As carbonatogenesis is neither restricted to particular taxonomic groups of bacteria nor to specific environments, it has been an ubiquitous phenomenon since Precambrian times. Carbonatogenesis is the response of heterotrophic bacterial communities to an enrichment of the milieu in organic matter. After a phase of latency, there is an exponential increase of bacterial numbers together with the accumulation of metabolic end-products. These induce a pH increase and an accumulation of carbonate and hydrogenocarbonate ions in the medium. This phase ends into a steady state when most part of the initial enrichment is consumed and there is a balance between death and growth in bacterial populations. Particulate carbonatogenesis occurs during the exponential phase and ends more or less after the beginning of the steady state. The active carbonatogenesis seems to start first and to be followed by the passive one which induces the growth of initially produced particles. In eutrophic conditions, the first solid products are patches that appear on the surface of the bacterial bodies and coalesce until forming a rigid coating and/or particles excreted from the cell. All these tiny particles assemble into biomineral aggregates which often display `precrystalline' structures. These aggregates grow and form biocrystalline build-ups which progressively display more crystalline structures with growth. In oligotrophic conditions, the primary solid products are rapidly smoothed in the crystalline structure and leave no trace. In present aqueous environments, apart from deep ocean, the potential efficiency of heterotrophic bacterial carbonatogenesis in Ca-carbonate sedimentation is much higher than autotrophic or abiotic processes. It much more likely accounts for extensive apparently abiotic limestone formation than any of the latter. As far as biodetrital particles are concerned, it may be observed that the shells and tests of organisms are built from the activity of cellular organites which are nowadays considered by a number of biologists as endosymbiotic bacteria. Thus, apart from (probably mythical) purely evaporitic and autotrophic ones, most limestones must be considered as principally of heterotrophic bacterial origin. As the carbon of limestones is issued from organic matter, bacterial heterotrophic carbonatogenesis appears as a fundamental phenomenon in the relationships between atmosphere and lithosphere during the biogeological evolution of the Earth.
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Microalgae biotechnology has recently emerged into the lime light owing to numerous consumer products that can be harnessed from microalgae. Product portfolio stretches from straightforward biomass production for food and animal feed to valuable products extracted from microalgal biomass, including triglycerides which can be converted into biodiesel. For most of these applications, the production process is moderately economically viable and the market is developing. Considering the enormous biodiversity of microalgae and recent developments in genetic and metabolic engineering, this group of organisms represents one of the most promising sources for new products and applications. With the development of detailed culture and screening techniques, microalgal biotechnology can meet the high demands of food, energy and pharmaceutical industries. This review article discusses the technology and production platforms for development and creation of different valuable consumer products from microalgal biomass.
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This review analyzes the current state of a specific niche of microalgae cultivation; heterotrophic growth in the dark supported by a carbon source replacing the traditional support of light energy. This unique ability of essentially photosynthetic microorganisms is shared by several species of microalgae. Where possible, heterotrophic growth overcomes major limitations of producing useful products from microalgae: dependency on light which significantly complicates the process, increase costs, and reduced production of potentially useful products. As a general role, and in most cases, heterotrophic cultivation is far cheaper, simpler to construct facilities, and easier than autotrophic cultivation to maintain on a large scale. This capacity allows expansion of useful applications from diverse species that is now very limited as a result of elevated costs of autotrophy; consequently, exploitation of microalgae is restricted to small volume of high-value products. Heterotrophic cultivation may allow large volume applications such as wastewater treatment combined, or separated, with production of biofuels. In this review, we present a general perspective of the field, describing the specific cellular metabolisms involved and the best-known examples from the literature and analyze the prospect of potential products from heterotrophic cultures.