Constantinos Ehaliotis

Agricultural University of Athens, Athínai, Attica, Greece

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Publications (37)95.84 Total impact

  • Ioannis Anastopoulos, Ioannis Massas, Constantinos Ehaliotis
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    ABSTRACT: Composting may alter the sorption properties of organic materials deriving from renewable sources. The widely available olive tree pruning waste (OTPW) and its composted form (COTPW) were comparatively tested for Pb2+ and Ni2+ removal in single- and double-metal systems. Pb2+ biosorption was higher than that of Ni2+ and increased metal biosorption was observed up to pH 5.0. The process followed pseudo-second order kinetics and described by the Langmuir isotherm. Surface area, total pore volume and zeta potential values were increased following composting, while cation exchange capacity was over-doubled (from 37.6 to 87.4 cmolc kg−1) leading to higher Pb2+ and Ni2+ biosorption and improved biosorption at elevated temperatures. There was 144%, 78%, and 148% increase in the maximum sorption capacity for Pb2+ and 29%, 59%, and 108% for Ni2+ at 10, 25 and 60 °C respectively. FTIR analysis indicated significant shifts in the chemical structure of OTPW as a result of composting, in line with oxidative decomposition processes. Among the desorption solutions tested, HNO3 and EDTA showed maximum recovery of both metals. Physisorption of both metals was greatly reduced by composting, leading to a biosorbent that retained Pb2+ and Ni2+ more efficiently. The suppressive effect of Ni2+ on Pb2+ sorption on OTPW throughout the whole range of Pb+2 concentrations, and the suppressive effect of Pb+2 on Ni+2 sorption at low Ni+2 concentrations were both alleviated when composted OTPW was used. Overall, OTPW proved to be a highly efficient biosorbent, especially for Pb2+, and composting resulted in multifunctional improvement of sorption characteristics.
    Chemical Engineering Journal 09/2013; 231:245–254. · 4.06 Impact Factor
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    ABSTRACT: Two composts were prepared from olive press cake (OPC) repeatedly turned and moistened with either olive mill wastewater (OPC+OMW) or water (OPC+W). When phytotoxicity was drastically reduced and the pH of the composts had reached 8.6 and 7.55 respectively, elemental sulfur was added at 0.9% of dry weight to the OPC+OMW compost and at five different doses (0.1 – 1.0% of dry wt) to the OPC+W compost. During the following six months, an exponential pH decline was observed in both compost materials. The pH reached a final value of 5.8 in the OPC+OMW compost whereas a pH decline related to the amount of added sulfur was observed in the OPC+W compost (final values from 6.8 to 4.3). Over 80% of the pH decline occurred during the first two months following the sulfur addition. Sulfur was applied following the stabilization of the material in the case of OPC+W. No phytotoxic effects of the final products were observed at sulfur application doses up to 0.5% of dry compost weight, but a significant germination index reduction was observed at the 1% dose, probably related to the increased conductivity of the compost leachate. Sulfur was applied before stabilization of the compost material, in the case of OPC+OMW, to also investigate the effects of sulfur addition on the composting process. A thermophilic phase similar to that observed after the last OMW application exceeding 50°C followed, and no effects on microbial activity profiles of the compost were observed. The results indicate that small amounts of elemental sulfur may efficiently control high pH values in the final compost products and could be safely applied at late composting stages or after composting. This may broaden the utilization of these composts in potting media and alkaline soils.
    Compost science & utilization 07/2013; 13(4):281-287. · 0.66 Impact Factor
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    ABSTRACT: The effects of time and a labile carbon (C) source on the fates of zinc (Zn) and copper (Cu) were investigated in a slightly acidic soil in a two-factor experiment. Glucose was used as the C source to examine the effect of the expected flush of microbial activity on Zn and Cu extractability during the experimental period. The soil was amended with 500 mg kg−1 soil of Zn and Cu in the form of nitrate salts and with 4 g kg−1 glucose where appropriate, producing M (heavy metals, no glucose) and MG (heavy metals, with glucose) treatments. The treated soil samples were incubated for 3 h, 1 day (24 h), 3 days (72 h), 10 days (240 h), 30 days (720 h), and 60 days (1440 h) at 20 °C at constant moisture (≈50% of the soil's water-holding capacity). At the end of each incubation period, destructive sampling was followed by a Tessier sequential extraction procedure that yielded five metal fractions for both Zn and Cu, defined as exchangeable, acid-soluble, reducible, oxidizable, and residual. The exchangeable fraction of Zn and Cu (considered to be an availability measure) showed decreasing trends over time, while the opposite was observed for the other fractions. The presence of glucose resulted in significantly lower exchangeable fractions in the “polluted soil” for both metals up to 720 h, pointing to lower Zn and Cu availability. Redistribution from less-available forms back to exchangeable forms occurred during the second month of incubation, suggesting a sharp decline in microbial activity and a consequent remobilization and potentially increased Zn and Cu bioavailability. However, glucose did not affect Zn and Cu availability in the control soil; this indicated that its effect is mainly observed following recent pollution events. Field applications of glucose at 4 g kg−1 soil is impractical in practice; future experimentation to estimate a minimum effective application rate or an alternative form of labile C, probably derived from recycling renewable labile organic materials, is warranted.
    Communications in Soil Science and Plant Analysis 05/2013; 44(1-4):722-732. · 0.42 Impact Factor
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    ABSTRACT: Glucosinolates (GSLs) are secondary metabolites found in Brassica species. Upon tissue disruption GSLs are hydrolyzed by myrosinase enzymes to isothiocyanates (ITCs) which are highly toxic to microbes. Therefore the incorporation of fresh Brassicaceae tissues into soil for the control of soil-born plant pathogens is viewed as a biofumigation process. Its efficacy relies on the rate of GSL conversion to ITCs, but also on environmental factors controlling GSL availability in the soil matrix. We studied the dissipation of GSLs, applied either by broccoli leaves or as pure compounds, in a clay loam soil at two soil moisture content levels. Regardless of their mode of application, GSLs were rapidly dissipated in soil with half-life values ranging from 3.2 to 15.5 h. Increasing moisture from 20 to 90% of the soil water holding capacity significantly accelerated their dissipation. Indolyl broccoli-derived GSLs dissipated faster than aliphatic GSLs at high moisture levels, while at low moisture levels a three-fold reduction in their dissipation rates was observed. The dissipation of aliphatic GSLs was less affected by soil moisture levels. Application of pure GSLs resulted in increased soil metabolic quotients (qCO2), suggesting a decline is microbial metabolic efficiency. Their dissipation was related to myrosinase activity apparently derived from soil microbes.
    European Journal of Soil Biology 05/2013; 56:49-55. · 2.15 Impact Factor
  • Michalis Omirou, Ioannis M. Ioannides, Constantinos Ehaliotis
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    ABSTRACT: Horticultural crops in the Mediterranean basin have to cope with severe drought conditions. The effect of inoculating watermelon plants grown under limited water availability conditions with AM fungi on the fruit yield, water use efficiency (WUE), root-N and -P content was examined. We focused on the impact of watering level and inoculation with allochthonous AM fungi on the diversity and presence of AM fungi in the watermelon roots using molecular techniques. An open field experiment was conducted and plants were grown with (M) and without AM fungal inoculum (NM), subjected to water stress (NW) and no stress conditions (W). Suboptimal water application (NW) resulted in significant reduction of fruit yield, root-N and -P content. Inoculation of plants grown under water stress resulted in a significant increase of WUE (19%), fruit yield (19%), root-N (27%) and -P (40%). However, only root-P responded to AM inoculation under non water stress conditions demonstrating 23% increase in M plants. DNA extracted from root samples was subjected to PCR–DGGE analysis. The native mycorrhizal population colonized watermelon roots, as indicated by DGGE bands in NM treatments. Some members of this colonizer community appear sensitive to the introduction of allochthonous inocula and to water stress conditions. Cloning and sequencing of AM fungi revealed that watermelon roots were colonized by Glomus and Paraglomus species. A TaqMan real-time PCR assay was also carried out targeting the 18S rRNA gene for the quantification of AM nucleic acids. The 18S rRNA copy numbers of AM fungi were significantly increased in M plants compared to NM plants under water stress. On the contrary, under non stress conditions M and NM plants did not show significant differences, indicating that inoculation with AM fungi was related to the response of plants to water stress conditions. Principle coordinate analysis of the DGGE banding patterns showed that the diversity of AM fungal colonizers was strongly affected (i) by inoculation and (ii) by water stress in the inoculated plants. Inoculation affected fungal presence under water limitation conditions only. The latter was in line with the significant beneficial effect of inoculation on both WUE and yield only under water limitation.
    Applied Soil Ecology 01/2013; 63:112–119. · 2.21 Impact Factor
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    ABSTRACT: Thirty-nine white-rot fungi belonging to nine species of Agaricomycotina (Basidiomycota) were initially screened for their ability to decrease olive-mill wastewater (OMW) phenolics. Four strains of Ganoderma australe, Ganoderma carnosum, Pleurotus eryngii and Pleurotus ostreatus, were selected and further examined for key-aspects of the OMW biodegradation process. Fungal growth in OMW-containing batch cultures resulted in significant decolorization (by 40-46% and 60-65% for Ganoderma and Pleurotus spp. respectively) and reduction of phenolics (by 64-67% and 74-81% for Ganoderma and Pleurotus spp. respectively). COD decrease was less pronounced (12-29%). Cress-seeds germination increased by 30-40% when OMW was treated by Pleurotus strains. Toxicity expressed as inhibition of Aliivibrio fischeri luminescence was reduced in fungal-treated OMW samples by approximately 5-15 times compared to the control. As regards the pertinent enzyme activities, laccase and Mn-independent peroxidase were detected for Ganoderma spp. during the entire incubation period. In contrast, Pleurotus spp. did not exhibit any enzyme activities at early growth stages; instead, high laccase (five times greater than those of Ganoderma spp.) and Mn peroxidases activities were determined at the end of treatment. OMW decolorization by Ganoderma strains was strongly correlated to the reduction of phenolics, whereas P. eryngii laccase activity was correlated with the effluent's decolorization.
    Chemosphere 04/2012; 88(5):620-6. · 3.14 Impact Factor
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    ABSTRACT: The high wastewater volumes produced during citrus production at pre- and post-harvest level presents serious pesticide point-source pollution for groundwater bodies. Biobeds are used for preventing such point-source pollution occurring at farm level. We explored the potential of biobeds for the depuration of wastewaters produced through the citrus production chain following a lab-to-field experimentation. The dissipation of pesticides used pre- or post-harvest was studied in compost-based biomixtures, soil, and a straw-soil mixture. A biomixture of composted grape seeds and skins (GSS-1) showed the highest dissipation capacity. In subsequent column studies, GSS-1 restricted pesticides leaching even at the highest water load (462 Lm(-3)). Ortho-phenylphenol was the most mobile compound. Studies in an on-farm biobed filled with GSS-1 showed that pesticides were fully retained and partially or fully dissipated. Overall biobeds could be a valuable solution for the depuration of wastewaters produced at pre- and post-harvest level by citrus fruit industries.
    Environmental Pollution 03/2012; 166:31-9. · 3.73 Impact Factor
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    ABSTRACT: Background and Aims Rocket salad (Eruca sativa Mills) is one of the major leafy vegetables produced worldwide and has been characterized as a rich source of chemoprotective glucosinolates (GSL). The relationship between N fertilization and the resulting plant biomass and N status with GSL quantity and quality in rocket leaves was examined. Methods A pot experiment was conducted, applying ten different N-rates and destructive sampling was carried out 15, 30 and 45 days after transplanting (DAT). The Mitscherlich equation was used to establish NO3-N critical levels at each growth stage and as an indicator of N demand for relative maximum dry matter accumulation and glucosinolate content and composition was determined. Results Glucosinolate content was significantly influenced by N rate, growth stage and their interaction. Different GSL types showed dissimilar responses to N fertilization: aliphatic GSLs were significantly reduced under increased N rates whereas indole GSL showed the reverse. Under excess N fertilization (>1.04 g/plant), dry matter accumulation remained constant, NO3-N was significantly increased and total GSL content was significantly reduced, factors that could lead to an anticipated product quality decline. Conclusions The application of the critical NO3-N level approach used to identify optimal N fertilization rates for plant growth could serve as means to obtain optimized GSL content in the edible plant parts.
    Plant and Soil 01/2012; 354(1):347-358. · 3.24 Impact Factor
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    ABSTRACT: a b s t r a c t Fusarium solani strain FsK (FsK), isolated from a plant pathogen-suppressive compost, grows endo-phytically in tomato roots and controls infestations by Fusarium oxysporum f.sp. radicis-lycopersici (FORL). The effect of root colonization by the two fungi on the diversity of rhizosphere microbial community was studied. Tomato plants were inoculated with FsK and/or FORL and rhizosphere soil was collected 8, 15 and 30 days post inoculation (dpi) and analyzed by denaturating gradient gel electrophoresis (DGGE) of PCR-amplified internal transcribed spacer (ITS) sequences of fungi and 16S rRNA gene sequences of common rhizosphere bacterial guilds like alpha-proteobacteria and pseudomonads. Cluster analysis of DGGE fingerprints showed that FsK had a transient impact on the fungal and alpha-proteobacterial community only during its endophytic stage (15 dpi), while FORL had a readily distinguished and persistent effect on the fungal community. The changes observed in the rhizosphere fungal and bacterial communities may depict the interactions of the two fungal inocula with the plant. Cloning of selected DGGE bands stimulated by FsK showed that the responsive bacteria were closely related to species known to include biological control agents (BCA). Overall, the inoculation of FsK in tomato rhizosphere did not appear to have a significant impact on the diversity of non-target microbial groups inhabiting plant rhizosphere.
    European Journal of Soil Biology 11/2011; 47(6):400-408. · 2.15 Impact Factor
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    ABSTRACT: Wastewaters from the fruit packaging industry contain a high pesticide load and require treatment before their environmental discharge. We provide first evidence for the potential bioremediation of these wastewaters. Three white rot fungi (WRF) (Phanerochaete chrysosporium, Trametes versicolor, Pleurotus ostreatus) and an Aspergillus niger strain were tested in straw extract medium (StEM) and soil extract medium (SEM) for degrading the pesticides thiabendazole (TBZ), imazalil (IMZ), thiophanate methyl (TM), ortho-phenylphenol (OPP), diphenylamine (DPA) and chlorpyrifos (CHL). Peroxidase (LiP, MnP) and laccase (Lac) activity was also determined to investigate their involvement in pesticide degradation. T. versicolor and P. ostreatus were the most efficient degraders and degraded all pesticides (10 mg l⁻¹) except TBZ, with maximum efficiency in StEM. The phenolic pesticides OPP and DPA were rapidly degraded by these two fungi with a concurrent increase in MnP and Lac activity. In contrast, these enzymes were not associated with the degradation of CHL, IMZ and TM implying the involvement of other enzymes. T. versicolor degraded spillage-level pesticide concentrations (50 mg l⁻¹) either fully (DPA, OPP) or partially (TBZ, IMZ). The fungus was also able to rapidly degrade a mixture of TM/DPA (50 mg l⁻¹), whereas it failed to degrade IMZ and TBZ when supplied in a mixture with OPP. Overall, T. versicolor and P. ostreatus showed great potential for the bioremediation of wastewaters from the fruit packaging industry. However, degradation of TBZ should be also achieved before further scaling up.
    Biodegradation 02/2011; 22(1):215-28. · 2.49 Impact Factor
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    C. Ehaliotis, A. Martinis, Ch. Minotou
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    ABSTRACT: The majority of innovations pioneered within/for the organic olive oil production (OOOP) chain may, and are, increasingly becoming, adopted by the conventional olive oil production chain, especially regarding cultivation, inputs related to plant/ecosystem protection and trade/promotion of specialized high quality products. Therefore the OOOP-chain may become a pioneering paradigm, for the implementation and convergence of agricultural production, marketing, sustainable rural development and environmental/biodiversity protection EU policies in the Mediterranean. Moreover, it appears that OOOP systems are increasingly becoming model systems for developing, applying and evaluating innovations that may have far more general applicability for Mediterranean agriculture. There is little divergence between conventional and organic production regarding water consumption and waste production, but the OOOP-chain has a lower impact as regards to soil erosion, desertification, pollution due chemicals and fertilizers (minimal), and effects on wildelife/vegetation biodiversity. Regarding pest and disease control, Bactrocera oleae is the most common pest problem, but effective means of control are available. On the contrary, Verticillium wilt is constantly expanding and, although not still a widespread problem, it is difficult to manage. Bottom-up demand for innovations, however, tends to underrate the need for innovations on common marketing priorities, trade policies, infrastructure and joint promotion strategies. Regarding “biopesticides” and “natural products”, approval protocols and legislation regarding synthetic inputs should also be fully applied to these products, to assure safe development of the OOOP sector. Key words: innovations, organic olive oil, sustainability , environmental protection, Biolmed project.
    http://orgprints.org/view/projects/int-conf-2011-abm.html. 01/2011;
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    ABSTRACT: Biofumigation (BIOF) is carried out mainly by the incorporation of brassica plant parts into the soil, and this fumigation activity has been linked to their high glucosinolate (GSL) content. GSLs are hydrolyzed by the endogenous enzyme myrosinase to release isothiocyanates (ITCs). A microcosm study was conducted to investigate the effects induced on the soil microbial community by the incorporation of broccoli residues into soil either with (BM) or without (B) added myrosinase and of chemical fumigation, either as soil application of 2-phenylethyl ITC (PITC) or metham sodium (MS). Soil microbial activity was evaluated by measuring fluorescein diacetate hydrolysis and soil respiration. Effects on the structure of the total microbial community were assessed by phospholipid fatty acid analysis, while the impact on important fungal (ascomycetes (ASC)) and bacterial (ammonia-oxidizing bacteria (AOB)) guilds was evaluated by denaturating gradient gel electrophoresis (DGGE). Overall, B, and to a lesser extent BM, stimulated microbial activity and biomass. The diminished effect of BM compared to B was particularly evident in fungi and Gram-negative bacteria and was attributed to rapid ITC release following the myrosinase treatment. PITC did not have a significant effect, whereas an inhibitory effect was observed in the MS-treated soil. DGGE analysis showed that the ASC community was temporarily altered by BIOF treatments and more persistently by the MS treatment, while the structure of the AOB community was not affected by the treatments. Cloning of the ASC community showed that MS application had a deleterious effect on potential plant pathogens like Fusarium, Nectria, and Cladosporium compared to BIOF treatments which did not appear to inhibit them. Our findings indicate that BIOF induces changes on the structure and function of the soil microbial community that are mostly related to microbial substrate availability changes derived from the soil amendment with fresh organic materials.
    Microbial Ecology 01/2011; 61(1):201-13. · 3.12 Impact Factor
  • Constantinos Ehaliotis, Ioannis Massas, Georgios Pavlou
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    ABSTRACT: Vegetable production demands high nitrogen inputs. Fertigation is a means to increase fertilizer-N use by plants. However, the effect of different N sources and doses, and how they relate to the total available N in soils are poorly known. In this study we applied 15N-labeled fertilizers to green pepper in the field using a drip irrigation system during the dry summer. KNO3-N and urea-N were applied at a total of 6, 12 and 18 g plant−1. Our results show that urea was as effective as KNO3 as a N source. The fertilizer-N utilization efficiency was dramatically reduced at higher N doses, from 48% for the 6 g N plant−1 dose to 36% and 26% for the 12 and 18 g N plant−1 doses, respectively. However, the N in plants derived from fertilizer consistently exceeded 60%, indicating high availability of fertilizer-N even at the lowest dose. Negative added nitrogen interactions — the effect of added N on the fate of soil-N — were observed, particularly at high fertilizer-N doses. The fertilizer-N utilization efficiency calculated by the difference method was lower compared with the 15N enrichment method. This clearly indicates luxury N applications and excess N availability brought about by precise localized placement of fertilizer-N that leads to limited uptake of the available soil-N. N leaching risks in the following rain period should therefore be based on both the residual fertilizer-N and the increased amounts of residual soil mineral-N.
    Agronomy for Sustainable Development 12/2010; 30(4). · 2.84 Impact Factor
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    ABSTRACT: This study reports on the concentrations, distribution, and availability of heavy metals in the children’s playground soils of Athens. Playgrounds were chosen because they are open city areas; they show relatively even spatial distribution within the district of Athens and are used by a great number of young children and their escorts on a regular basis. Samples were collected from 70 playground surface soils, representing more than 70% of the city’s playgrounds. Cu, Zn, Pb, Cr, Ni, Co, Mn, and Fe were extracted by aqua regia and by diethylene triamine pentaacetic acid (DTPA) to estimate total and available metal forms, respectively. Their mean total concentrations were 43, 174, 110, 80, 82, 22, 312, and 17 × 103 mgkg−1, respectively. The DTPA-extracted fraction showed much lower values, with means of 2.5, 7.8, 5.8, 1.5, 1.3, 0.4, 8.4, and 2.0mgkg−1 respectively, which, however, should be carefully monitored since they relate directly to the bioavailable fraction of heavy metals. Though mean values of metal concentrations are not particularly high, the calculated enrichment factors indicate site-specific cases of high enrichment with heavy metals. Considering that the bioavailable fraction of a metal is possibly a more appropriate indicator for the recent soil pollution history, availability ratios were calculated and their distribution was visualized over the entire city profile using the appropriate GIS software. It was shown that recent metal pollution events appear to have affected mostly playground sites in the southern and eastern part of the municipality. KeywordsUrban soils-Heavy metals-Playgrounds-Enrichment factor-Metal availability-Metal pollution
    Water Air and Soil Pollution 10/2010; 212(1):51-63. · 1.69 Impact Factor
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    ABSTRACT: Biobeds have been used in northern Europe for minimizing point source contamination of water resources by pesticides. However, little is known regarding their use in southern Europe where edaphoclimatic conditions and agriculture practices significantly differ. A first step toward their adaptation in southern Europe is the use of low-cost and easily available substrates as biomixture components. This study investigated the possibility of replacing peat with agricultural composts in the biomixture. Five composts from local substrates including olive leaves, cotton crop residues, cotton seeds, spent mushroom substrate, and commercial sea wrack were mixed with topsoil and straw (1:1:2). Degradation of a mixture of pesticides (dimethoate, indoxacarb, buprofezin, terbuthylazine, metribuzin, metalaxyl-M, iprodione, azoxystrobin) at two dose rates was tested in the compost biomixtures (BX), in corresponding peat biomixtures (OBX), and in soil. Adsorption-desorption of selected pesticides were also studied. Pesticide residues were determined by gas chromatography with nitrogen-phosphorus detector, except indoxacarb, which was determined with a microelectron capture detector. Overall, BX degraded the studied pesticides at rates markedly higher than those observed in soil and OBX, in which the slowest degradation rates were evident. Overall, the olive leaf compost biomixture showed the highest degradation capacity. Adsorption studies showed that OBX and BX had higher adsorption affinity compared to soil. Desorption experiments revealed that pesticide adsorption in biomixtures was not entirely reversible. The results suggest that substitution of peat with local composts will lead to optimization of the biobed system for use in Mediterranean countries.
    Journal of Agricultural and Food Chemistry 07/2010; · 3.11 Impact Factor
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    ABSTRACT: Microbial assessment of grape marc wastes, the residual solid by-product of the wine-industry, was performed by identifying phylogenetically the fungal culturable diversity in order to evaluate environmental and disposal safety issues and to discuss ecological considerations of applications on agricultural land. Fungal spores in grape marc were estimated to 4.7 x 10(6) per g dry weight. Fifty six fungal isolates were classified into eight operational taxonomic units (OTUs) following amplified ribosomal DNA restriction analysis (ARDRA) and colony morphology. Based on 18S rRNA gene and 5.8S rRNA gene-ITS sequencing, the isolates representing OTUs #1, #2, #3, and #4, which comprised 44.6%, 26.8%, 12.5%, and 5.3%, respectively, of the number of the total isolates, were identified as Aspergillus fumigatus, Bionectria ochroleuca, Haematonectria haematococca, and Trichosporon mycotoxinivorans. The isolates of OTU#5 demonstrated high phylogenetic affinity with Penicillium spp., while members of OTUs #6 and #7 were closer linked with Geotrichum candidum var. citri-aurantii and Mycocladus corymbifer, respectively (95.4 and 97.9% similarities in respect to their 5.8S rRNA gene-ITS sequences). The OTU#8 with a single isolate was related with Aspergillus strains. It appears that most of the fungal isolates are associated with the initial raw material. Despite the fact that some of the species identified may potentially act as pathogens, measures such as the avoidance of maintaining large and unprocessed quantities of grape marc wastes in premises without adequate aeration, together with its suitable biological treatment (e.g., composting) prior to any agriculture-related application, could eliminate any pertinent health risks.
    The Journal of Microbiology 06/2010; 48(3):297-306. · 1.28 Impact Factor
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    ABSTRACT: Rhizospheric and root-associated/endophytic (RAE) bacteria were isolated from tomato plants grown in three suppressive compost-based plant growth media derived from the olive mill, winery and Agaricus bisporus production agro-industries. Forty-four (35 rhizospheric and 9 RAE) out of 329 bacterial strains showed in vitro antagonistic activity against at least one of the soil-borne fungal pathogens, Fusarium oxysporum f.sp. radicis-lycopersici (FORL), F. oxysporum f.sp. raphani, Phytophthora cinnamomi, P. nicotianae and Rhizoctonia solani. The high percentage of total isolates showing antagonistic properties (13%) and their common chitinase and β-glucanase activities indicate that the cell wall constituents of yeasts and macrofungi that proliferate in these compost media may have become a substrate that favours the establishment of antagonistic bacteria to soil-borne fungal pathogens. The selected bacterial strains were further evaluated for their suppressiveness to tomato crown and root rot disease caused by FORL. A total of six rhizospheric isolates, related to known members of the genera Bacillus, Lysinibacillus, Enterobacter and Serratia and one RAE associated with Alcaligenes faecalis subsp. were selected, showing statistically significant decrease of plant disease incidence. Inhibitory effects of extracellular products of the most effective rhizospheric biocontrol agent, Enterobacter sp. AR1.22, but not of the RAE Alcaligenes sp. AE1.16 were observed on the growth pattern of FORL. Furthermore, application of cell-free culture extracts, produced by Enterobacter sp. AR1.22, to tomato roots led to plant protection against FORL, indicating a mode of biological control action through antibiosis. KeywordsRhizosphere-Suppressive compost-Endophytic-Chitinase-Fungal antagonist- Enterobacter -Antibiosis
    Plant and Soil 05/2010; 333(1):233-247. · 3.24 Impact Factor
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    ABSTRACT: Repeated application of diluted olive mill wastewater (OMW) is a common disposal method which allows the application of large amounts of OMW and improves the organic matter and nutrient status of Mediterranean soils. However, there is lack of information regarding the effects of this practice on the soil microbial community. A study was carried out to investigate these effects on the structure of the bacterial and fungal community of a loamy sand (LS) and a sandy loam (SL) soil, using denaturating gradient gel electrophoresis (DGGE) fingerprinting. OMW was daily applied as aqueous solutions of 0, 2 and 4%, in the presence or absence of nitrogen fertilization, for a three-month period. Multivariate analysis of the DGGE profiles showed that OMW applications resulted in marked changes in the fungal community in both soils, while nitrogen fertilization diminished these effects. Small effects were evident for the bacteria only in the LS soil and this was attributed to the higher availability of OMW-derived phenolics in this soil which resulted in a direct impact on bacteria. Nitrogen fertilization alleviated the effects of OMW on the bacterial community. We suggest that the impact of OMW on the structure of the soil microbial communities was mostly a result of its indirect effect on the soil nutritional status, which becomes enriched in organic substrates and poor in available nitrogen.
    European Journal of Soil Biology 01/2010; · 2.15 Impact Factor
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    ABSTRACT: Recycling of olive mill wastewaters (OMW) into agricultural soils is a controversial issue since benefits to soil fertility should counterbalance potential short-term toxicity effects. We investigated the short-term effects of OMW on the soil–plant system, regarding the diversity, structure and root colonization capacity of arbuscular mycorrhizal (AM) fungi and the respective growth response of Vicia faba L, commonly used as green manure in olive-tree plantations. A compartmentalized pot system was used that allowed the establishment of an AM fungal community in one compartment (feeder) and the application of three OMW dose levels in an adjacent second compartment (receiver). At 0, 10, and 30 days after OMW treatment (DAT), V. faba pre-germinated seeds were seeded in the receiver compartment. At harvest, shoot and root dry weights, AM fungal root colonization, soil hyphal length and P availability were recorded in the receiver compartment. In addition, OMW effects on AM fungal diversity in plant roots were studied by DGGE. A transient effect of OMW application was observed; plant growth and AM fungal colonization were initially inhibited, whereas soil hyphal length was stimulated, but in most cases differences were absent when seeding was performed 30 DAT. Similarly, changes induced in the structure of the root AM fungal community were of transient nature. Cloning and sequencing of all the major DGGE bands showed that roots were colonized by Glomus spp. The transient effects of OMW on the structure and function of AM fungi could be attributed to OMW-derived phytoxicity to V. faba plants or to an indirect effect via alteration of soil nutritional status. The high OMW dose significantly increased soil P availability in the presence of AM fungi, suggesting efficient involvement of AM fungi in organic-P minerilization. Overall our results indicate that soil application of OMW would cause transient changes in the AM fungal colonization of V. faba plants, which, would not impair their long-term plant growth promoting ability.
    Soil Biology and Biochemistry 12/2009; · 4.41 Impact Factor
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    ABSTRACT: Olive mill wastewater (OMW) is rich in potentially toxic organics precluding its disposal into water receptors. However, land application of diluted OMW may result in safe disposal and fertilization. In order to investigate the effects of OMW on the structure of soil fungal groups, OMW was applied daily to pepper plants growing in a loamy sand and a sandy loam at two doses for a period of 3 months (total OMW equivalents 900 and 1800 m(3) ha(-1)). Nitrogen (N) fertilization alleviated N scarcity and considerably enhanced plant biomass production; however, when applied in combination with the high OMW dose, it induced plant stress. OMW applications resulted in marked changes in the denaturing gradient gel electrophoresis patterns of soil basidiomycete communities, while concurrent N fertilization reduced these effects. In contrast, the ascomycete communities required N fertilization to respond to OMW addition. Cloning libraries for the basidiomycete communities showed that Cryptococcus yeasts and Ceratobasidium spp. dominated in the samples treated with OMW. In contrast, certain plant pathogenic basidiomycetes such as Thanatephorus cucumeris and Athelia rolfsii were suppressed. The observed changes may be reasonably explained by the capacity of OMW to enrich soils in organic substrates, to induce N immobilization and to directly introduce OMW-derived basidiomycetous yeasts.
    FEMS Microbiology Ecology 09/2009; 70(3):388-401. · 3.88 Impact Factor

Publication Stats

473 Citations
95.84 Total Impact Points

Institutions

  • 2002–2013
    • Agricultural University of Athens
      • • Laboratory of Soil Science and Agricultural Chemistry
      • • Laboratory of Pesticide Science
      Athínai, Attica, Greece
  • 2009–2010
    • University of Thessaly
      • • Department of Agriculture Crop Production and Rural Environment
      • • Department of Biochemistry and Biotechnology
      Lárisa, Thessalia, Greece