Search

Anoxic sediments, as compared to oxic settings, encompass a much higher proportion of relatively labile and thus more reactive organic matter, naturally giving rise to structural changes of the organic molecules themselves, as well as cross-linking between them (e.g., through reactive sulfur species). Both processes transform the original biomolecules into geomolecules. For the oxic environment, these intermolecular and intramolecular transformations also operate, but cross-linking may be less important since the labile, reactive component is rapidly removed. As such, one may expect a structurally better preservation of the more refractory initial biomolecules in the oxic environment. To test this hypothesis, initially identical biomolecules need to be compared between different preservational environments. Here, we use the species-specific morphology of organic microfossils to assure a single initial biosynthetic product (the cysts of the fossil dinoflagellate species Thalassiphora pelagica) for comparison. We assess the macromolecular structures of cysts from the Eocene ( ∼ 40 Ma) sulfidic Rhine Graben and the oxic Kerguelen Plateau and compare them with each other and the structures of recent cysts. While between the sites the T. pelagica cysts are morphologically identical and show no signs of morphological modification, pyrolysis gas chromatography mass spectroscopy and micro Fourier transform infrared analyses show that their macromolecular characteristics are strongly different. Comparison with recent cysts shows that the cysts deposited in the sulfidic Rhine Graben show a strong additional contribution of long-chain aliphatic moieties and thus less diagenetic intermolecular cross-linking. The presence of organic sulfur identifies natural volcanization as one of the diagenetic processes. Furthermore, we observe a loss of bound oxygen and no trace of the original carbohydrate signature of the cyst wall biomacromolecule. The material deposited in the oxic sediments of the Kerguelen Plateau shows no traces of sulfurization. It shows a minor contribution of short carbon chains only and thus less diagenetic intermolecular crosslinking. Furthermore, a carbohydrate signature was still preserved evidencing a better molecular preservation of the initial biomacromolecule, supporting our initial hypothesis. This shows that excellent morphological preservation does not imply excellent chemical preservation. It also leads to the conclusion that the best preservation of molecular structure is not necessarily where most organic matter gets preserved, which, in turn, is important for understanding the nature and fate of sedimentary organic matter and its isotopic signature. © 2020 Author(s).

Anoxic sediments, as compared to oxic settings, encompass a much higher proportion of relatively labile and thus more reactive organic matter, naturally giving rise to structural changes of the organic molecules themselves, as well as cross-linking between them (e.g., through reactive sulfur species). Both processes transform the original biomolecules into geomolecules. For the oxic environment, these intermolecular and intramolecular transformations also operate, but cross-linking may be less important since the labile, reactive component is rapidly removed. As such, one may expect a structurally better preservation of the more refractory initial biomolecules in the oxic environment. To test this hypothesis, initially identical biomolecules need to be compared between different preservational environments. Here, we use the species-specific morphology of organic microfossils to assure a single initial biosynthetic product (the cysts of the fossil dinoflagellate species Thalassiphora pelagica) for comparison. We assess the macromolecular structures of cysts from the Eocene ( ∼ 40 Ma) sulfidic Rhine Graben and the oxic Kerguelen Plateau and compare them with each other and the structures of recent cysts. While between the sites the T. pelagica cysts are morphologically identical and show no signs of morphological modification, pyrolysis gas chromatography mass spectroscopy and micro Fourier transform infrared analyses show that their macromolecular characteristics are strongly different. Comparison with recent cysts shows that the cysts deposited in the sulfidic Rhine Graben show a strong additional contribution of long-chain aliphatic moieties and thus less diagenetic intermolecular cross-linking. The presence of organic sulfur identifies natural volcanization as one of the diagenetic processes. Furthermore, we observe a loss of bound oxygen and no trace of the original carbohydrate signature of the cyst wall biomacromolecule. The material deposited in the oxic sediments of the Kerguelen Plateau shows no traces of sulfurization. It shows a minor contribution of short carbon chains only and thus less diagenetic intermolecular crosslinking. Furthermore, a carbohydrate signature was still preserved evidencing a better molecular preservation of the initial biomacromolecule, supporting our initial hypothesis. This shows that excellent morphological preservation does not imply excellent chemical preservation. It also leads to the conclusion that the best preservation of molecular structure is not necessarily where most organic matter gets preserved, which, in turn, is important for understanding the nature and fate of sedimentary organic matter and its isotopic signature. © 2020 Author(s).

In this study, axenic cultures of sulfate-reducing (SRB) and nitrate-reducing (NRB) bacteria were examined for their ability to methylate inorganic tin and to methylate or dealkylate butyltin compounds. Environmentally relevant concentrations of natural abundance tributyltin (TBT) and 116Sn-enriched inorganic tin were added to bacterial cultures to identify bacterial-mediated methylation and dealkylation reactions. The results show that none of the Desulfovibrio strains tested was able to induce any transformation process. In contrast, Desulfobulbus propionicus strain DSM-6523 degraded TBT either under sulfidogenic or non-sulfidogenic conditions. In addition, it was able to alkykate 116Sn-enriched inorganic tin leading to the formation of more toxic dimethyltin and trimethyltin. A similar capacity was observed for incubations of Pseudomonas but with a much greater dealkykation of TBT. As such, Pseudomonas sp. ADR42 degraded 61% of the initial TBT under aerobic conditions and 35% under nitrate-reducing conditions. This is the first work reporting a simultaneous TBT degradation and a methylation of both inorganic tin species and TBT dealkykation products by SRB and NRB under anoxic conditions. These reactions are environmentally relevant as they can control the mobility of these compounds in aquatic ecosystems; as well as their toxicity toward resident organisms. © 2018 Elsevier P.R.G. would like to acknowledge the postdoctoral fellowship from the “Secretaria de Estado de Universidades e Investigacion” of the Spanish Ministry of Education and Science. P.N. would like to acknowledge the Doctoral fellowship from the Basque Country. This project was funded by French National Research Agency ( ANR – Jeune Chercheur program) in the framework of the MINAMETA project ( JCJC2006-0044 ). T. Stoichev is grateful to the Foundation for Science and Technology for fellowship SFRH/BPD/88675/2012 , co-financed by Programa Operacional Potencial Humano (POPH) /Fundo Social Europeu (FSE). Appendix A

The paper expresses an attempt to tackle the problem due to the presence of micropollutants in wastewater which may be able to disrupt the endocrine system of some organisms. These kinds of compounds are ubiquitously present in municipal wastewater treatment plant (WWTP) effluents. The aim of this paper is to compare the fate of the alkylphenols-APs (4-(tert-octyl)) phenol, t-nonylphenol and 4-p-nonylphenol and the hormones (estrone, 17ß-estradiol and 17¿-ethinylestradiol) in a submerged anaerobic membrane bioreactor (SAMBR) pilot plant and in a conventional activated sludge wastewater treatment plant (CTP). The obtained results are also compared with the results obtained in a previous study carried out in an aerobic MBR pilot plant. The results showed that the APs soluble concentrations in the SAMBR effluent were always significantly higher than the CTP ones. Moreover, the analyses of the suspended fraction revealed that the AP concentrations in the SAMBR reactor were usually higher than in the CTP reactor, indicating that under anaerobic conditions the APs were accumulated in the digested sludge. The aerobic conditions maintained both in the CTP system and in the aerobic MBR favoured the APs and hormones degradation, and gave rise to lower concentrations in the effluent and in the reactor of these systems. Furthermore, the results also indicated that the degradation of APs under aerobic conditions was enhanced working at high solid retention time (SRT) and hydraulic retention time (HRT) values. © IWA Publishing 2012., This research was financially supported by the Government of the Region of Valencia (Generalitat Valenciana), within the research project 'Application of Water Framework Directive 2000/60/EC on endocrine disruptors and priority substances in coastal areas in the Comunidad Valenciana' and by the Spanish Research Foundation (MICINN, project CTM2008-060809-C02-01/TECNO), within the research project 'Feasibility of the SAMBR technology to treat urban wastewater, and the technical and economic feasibility to industrial implementation'.

A bacterium, strain BC, was isolated from a benzene-degrading chlorate-reducing enrichment culture. Strain BC degrades benzene in conjunction with chlorate reduction. Cells of strain BC are short rods that are 0.6 μm wide and 1 to 2 μm long, are motile, and stain gram negative. Strain BC grows on benzene and some other aromatic compounds with oxygen or in the absence of oxygen with chlorate as the electron acceptor. Strain BC is a denitrifying bacterium, but it is not able to grow on benzene with nitrate. The closest cultured relative is Alicycliphilus denitrificans type strain K601, a cyclohexanol-degrading nitrate-reducing betaproteobacterium. Chlorate reductase (0.4 U/mg protein) and chlorite dismutase (5.7 U/mg protein) activities in cell extracts of strain BC were determined. Gene sequences encoding a known chlorite dismutase ( cld ) were not detected in strain BC by using the PCR primers described in previous studies. As physiological and biochemical data indicated that there was oxygenation of benzene during growth with chlorate, a strategy was developed to detect genes encoding monooxygenase and dioxygenase enzymes potentially involved in benzene degradation in strain BC. Using primer sets designed to amplify members of distinct evolutionary branches in the catabolic families involved in benzene biodegradation, two oxygenase genes putatively encoding the enzymes performing the initial successive monooxygenations (BC-BMOa) and the cleavage of catechol (BC-C23O) were detected. Our findings suggest that oxygen formed by dismutation of chlorite can be used to attack organic molecules by means of oxygenases, as exemplified with benzene. Thus, aerobic pathways can be employed under conditions in which no external oxygen is supplied.

Старење бунара настаје као последица процеса корозије и колмирања. Процесе корозије могуће је спречити уградњом филтерских конструкција од материјала отпорних на корозију. Колмирање може да настане без обзира на врсту материјала од кога се праве бунарске конструкције, а процесом може бити захваћена прифилтарска зона па и зона саме водоносне средине. Из тог разлога тезa је усмеренa на процесе који доводе до колмирања бунара и последицe опадањa капацитета водозахватних објеката. Полазна хипотеза је да бунари старе различитом брзином у срединама различитог степена оксичности. Хидрохемијске и микробиолошке карактеристике подземних вода, састав седимената изданске зоне, али и режим рада бунара утичу на брзину формирања талога у бунарима. Водоснабдевање становништва у Републици Србији врши се највећим делом експлоатацијом подземних вода (oкo 75%). Процењене количине подземних вода у алувијалним срединама износе 43,79 m3/s, што износи 65,23% укупно процењених природних резерви. На основу података из Водопривредне основе Републике Србије, просечно се из алувијалних издани експлоатише 12,9 m3/s. Подземне воде захваћене из алувијалних издани доминантно учествују у водоснабдевању у Србији. Одабрана су три подручја истраживања: регионална изворишта јавног водоснабдевања Трновче код Велике Плане и Кључ код Пожаревца, односно локација дренажног система Ковин-Дубовац која је Водопривредном основом предвиђена за отварање регионалног изворишта за водоснабдевање средњег и северног Баната. Резултати истраживања допуњени су и упоређени са подацима везаним за одабране бунаре београдског изворишта подземних вода. Кроз дисертацију су приказане методе које су коришћене за одређивање различитих параметара битних за дефинисање колмирања, геолошке и хидрогеолошке карактеристике појединачних локација, начин и резултати дефинисања степена оксичности средине, резултати анализе талога и резултати одређивања локалних хидрауличких губитака и дозвољених улазних брзина у бунаре... Water well ageing is generally a consequence of corrosion and clogging. Corrosion can be prevented by installing well casings made from materials resistant to corrosion. Clogging might occur regardless of the type of material used to construct the well casing and the process may extend to the immediate vicinity of the well screen and even affect the aquifer itself. For the above reason, focus of the thesis is on the processes that lead to well clogging and the impact of such processes on declining well capacity. The starting hypothesis is that wells age at varying rates in sediments of different oxic conditions. Hydrochemical and microbiological characteristics of the groundwater and the composition of the sediments comprising the aquifer matrix affect the rate of incrustation inside the wells, as does the operating mode of the wells. Drinking water supply in Serbia largely relies on groundwater abstraction (about 75%). The amount of groundwater stored in alluvial aquifers has been estimated at 43.79 m3/s, or 65.23% of all groundwater resources. According to the Serbia’s Water Management Master Plan, the average rate of groundwater from alluvial aquifers is 12.9 m3/s. Groundwater withdrawn from alluvial aquifers is the main source of the water supply in Serbia. Three test areas were selected: regional sources of public water supply at Trnovče near the City of Velika Plana and Ključ near the City of Požarevac, and the location of the Kovin-Dubovac drainage system that the Water Management Master Plan has designated for the development of a regional source of water supply for Central and North Banat. The outcomes of the research have been supplemented and compared with the data gathered from the selected water wells of the groundwater source in Belgrade. The thesis presents the methods applied to determine various parameters relevant to the definition of clogging, the geological and hydrogeological characteristics of the studied locations, the approach used and the outcomes of the definition of the oxic conditions of alluvial sediments, the incrustation analyses and the results of determining local hydraulic losses and permissible entrance velocities to the wells...

Старење бунара настаје као последица процеса корозије и колмирања. Процесекорозије могуће је спречити уградњом филтерских конструкција од материјалаотпорних на корозију. Колмирање може да настане без обзира на врсту материјалаод кога се праве бунарске конструкције, а процесом може бити захваћенаприфилтарска зона па и зона саме водоносне средине. Из тог разлога тезa јеусмеренa на процесе који доводе до колмирања бунара и последицe опадањaкапацитета водозахватних објеката. Полазна хипотеза је да бунари стареразличитом брзином у срединама различитог степена оксичности. Хидрохемијскеи микробиолошке карактеристике подземних вода, састав седимената изданскезоне, али и режим рада бунара утичу на брзину формирања талога у бунарима.Водоснабдевање становништва у Републици Србији врши се највећим деломексплоатацијом подземних вода (oкo 75%). Процењене количине подземних водау алувијалним срединама износе 43,79 m3/s, што износи 65,23% укупнопроцењених природних резерви. На основу података из Водопривредне основеРепублике Србије, просечно се из алувијалних издани експлоатише 12,9 m3/s.Подземне воде захваћене из алувијалних издани доминантно учествују уводоснабдевању у Србији. Одабрана су три подручја истраживања: регионалнаизворишта јавног водоснабдевања Трновче код Велике Плане и Кључ кодПожаревца, односно локација дренажног система Ковин-Дубовац која јеВодопривредном основом предвиђена за отварање регионалног изворишта заводоснабдевање средњег и северног Баната. Резултати истраживања допуњени суи упоређени са подацима везаним за одабране бунаре београдског извориштаподземних вода.Кроз дисертацију су приказане методе које су коришћене за одређивањеразличитих параметара битних за дефинисање колмирања, геолошке ихидрогеолошке карактеристике појединачних локација, начин и резултатидефинисања степена оксичности средине, резултати анализе талога и резултатиодређивања локалних хидрауличких губитака и дозвољених улазних брзина убунаре... Water well ageing is generally a consequence of corrosion and clogging. Corrosion canbe prevented by installing well casings made from materials resistant to corrosion.Clogging might occur regardless of the type of material used to construct the wellcasing and the process may extend to the immediate vicinity of the well screen and evenaffect the aquifer itself. For the above reason, focus of the thesis is on the processes thatlead to well clogging and the impact of such processes on declining well capacity. Thestarting hypothesis is that wells age at varying rates in sediments of different oxicconditions. Hydrochemical and microbiological characteristics of the groundwater andthe composition of the sediments comprising the aquifer matrix affect the rate ofincrustation inside the wells, as does the operating mode of the wells.Drinking water supply in Serbia largely relies on groundwater abstraction (about 75%).The amount of groundwater stored in alluvial aquifers has been estimated at 43.79 m3/s,or 65.23% of all groundwater resources. According to the Serbia’s Water ManagementMaster Plan, the average rate of groundwater from alluvial aquifers is 12.9 m3/s.Groundwater withdrawn from alluvial aquifers is the main source of the water supply inSerbia. Three test areas were selected: regional sources of public water supply atTrnovče near the City of Velika Plana and Ključ near the City of Požarevac, and thelocation of the Kovin-Dubovac drainage system that the Water Management MasterPlan has designated for the development of a regional source of water supply for Centraland North Banat. The outcomes of the research have been supplemented and comparedwith the data gathered from the selected water wells of the groundwater source inBelgrade.The thesis presents the methods applied to determine various parameters relevant to thedefinition of clogging, the geological and hydrogeological characteristics of the studiedlocations, the approach used and the outcomes of the definition of the oxic conditions of alluvial sediments, the incrustation analyses and the results of determining local hydraulic losses and permissible entrance velocities to the wells... water well ageing, alluvial aquifers, oxic conditions, clogging,incrustations, local hydraulic loss, permissible entrance velocity

The volume of wastewaters originating from dairy production has been increasing day by day parallel with the increasing dairy production and 90 percent of those wastewaters consist of cheese whey wastewater. Cheese whey has a high strength structure and cannot be treated by only aerobic biological treatment. The scope of this study, was to investigate the treatment of cheese whey wastewater in a system consisting of an anaerobic hybrid reactor followed by CSTR. Bio-one (TM) (microbial liquid fertilizer) was used to accelerate the start-up period of the anaerobic hybrid reactor. Bio-one (TM) addition to the anaerobic sludge resulted significantly high COD removal efficiency and methane generation with shorter acclimation period in the start-up phase. In this study, maximum COD.m(-3).d(-1) removal efficiency (91 %) was obtained at 2.53 kg OLR and 3.2 days of HRT in anaerobic hybrid reactor. Total COD removal efficiency of the sequential anaerobic/aerobic system was 96 %. It can be concluded that operating an anaerobic hybrid reactor after a CSTR for 412 days was an effective method for the treatment of cheese whey wastewater.

This paper analyses the valuable information provided by the on-line measurements of pH and oxidation reduction potential (ORP) in a continuous single high ammonia removal over nitrite (SHARON) reactor. A laboratory-scale SHARON reactor equipped with pH, ORP, electric conductivity and dissolved oxygen (DO) probes has been operated for more than one year. Nitrogen removal over nitrite has been achieved by adding methanol at the beginning of anoxic stages. Time evolution of pH and ORP along each cycle allows identifying the decrease in nitritation rate when ammonia is consumed during the aerobic phase and the end of the denitrification process during the anoxic phase. Therefore, monitoring pH and ORP can be used to develop a real-time control system aimed at optimizing the length of both aerobic and anoxic stages. Real-time control of methanol addition can be carried out by using the information provided by these probes: excessive methanol addition in the anoxic stage is clearly detected in the ORP profile of the following aerobic phase, while a deficit of methanol is detected in both pH and ORP profiles of that anoxic phase. Moreover, other valuable information such as the amount of ammonia nitrified, failures in DO measurements, excessive stirring during the anoxic stage and methanol dosage in the aerobic phase was also provided by the pH and ORP profiles. © IWA Publishing 2011., Financial support from MCYT (project CTM2005-06919-C03/TECN), Generalitat Valenciana (ACOMP06/144), and Universidad Politecnica de Valencia (UPV-FPI grant 2008-11 and PAID-06-06) are gratefully acknowledged.

Maize was harvested at one-third milk line (297 g kg-1 DM) stage. All inoculants were applied at 1 x 106 cfu g-1 of fresh forage. After treatment, the chopped forages were ensiled in 1 center dot 5-L anaerobic jars. Three jars per treatment were sampled on days 2, 4, 7, 12 and 90 after ensiling, for chemical and microbiological analysis. Homofermentative LAB-inoculated silages had lower pH and higher lactate:acetate ratio (except for Lactobacillus plantarum/Pediococcus cerevisiae and L. plantarum/Propionibacterium acidipropionici) than the control and both heterofermentative LAB-inoculated silages. Both L. buchneri inhibited yeast growth and CO2 production during exposure of silage to air. The L. plantarum/P. cerevisiae, L. plantarum (Ecosyl) and L. plantarum/Enterococcus faecium-inoculated silages had higher dry-matter digestibility than the control and L. buchneri-inoculated silages. Inoculants did not affect digestibility of neutral detergent fibre, except for L. buchneri (Biotal), organic matter nor ME content of silages. The LAB silage inoculants generally had a positive effect on maize silage characteristics in terms of lower pH and shifting fermentation toward lactate with homofermentative LAB or toward acetate with L. buchneri. The use of L. buchneri can improve the aerobic stability of maize silages by the inhibition of yeast activity.

To investigate biodegradability by Trametes versicolor, five structurally different direct azo-dyes - Direct Black 38, Direct Blue 15 (DB 15), Direct Orange 26, Direct Green 6, and Direct Yellow 12 - were studied. The DB 15 was determined as the best biodegradable dye by this white-rot fungus. Laccase and manganese peroxidase activities were monitored with the biodegradation process; it was observed that laccase played an important role in the dye degradation, while manganese peroxidase activity could not be detected. Possible degradation products also were examined by gas chromatography-mass spectrometry, but no metabolite was detected after the degradation and/or decolorization process. To enhance performance of the fungi during the degradation, Trametes versicolor cells were immobilized in alginate beads. Then, DB 15 decolorization by immobilized Trametes versicolor was studied in a small-scale packed-bed reactor. The color removal efficiency in repeated batches was found to be 98 and 93% for 50 mg/L DB 15. © 2010 Publishing Technology.

The effects of phenol, 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP) and 1,2,4-trichlorobenzene (1,2,4-TCB) on the biodegradation kinetics of the conventional activated sludge system (CASS) and the selector activated sludge system (SASS) were investigated. Experiments were carried out using a respirometric method on unacclimated biomass from two lab-scale systems that were operated with the sludge age of 8 days. Toxicity of the test compounds for both reactors were arranged according to EC 50 (effective concentration) values in order as: 1,2,4-TCB > 2,4-DCP > 2-CP > phenol. All selected test compounds induced higher inhibition effect in the CASS. The SASS appeared to reduce inhibition effect in comparison to the CASS, by 21.36%, 66.95%, 64.37% and 33.33% for phenol, 2-CP, 2,4-DCP and 1,2,4-TCB, respectively. Consequently, the SASS may be recommended as a promising configuration alternative for the waste streams containing toxic compounds.

In this study COD, ammonia and nitrate were treated through methanogenesis, nitrification denitrification and anammox processes in anaerobic-aerobic and anaerobic/anoxic sequential in leachate samples produced from municipal solid waste in an anaerobic simulated landfilling bioreactor. The experiments were performed in an upflow anaerobic sludge blanket reactor (UASB), aerobic completely stirred tank reactor (CSTR) and upflow anaerobic/anoxic sludge blanket reactor (UA/ANSB). Hydraulic retention times in anaerobic, aerobic and anaerobic/anoxic stages were 1, 3.6 and 1 days, respectively, through 244 days of total operation period with 168 days of adaptation period of microorganisms to the reactors. The organic loading rates increased from 5.9 to 50 kg COD m-3 day-1. The total COD and TN removal efficiencies of the anaerobic-aerobic-anoxic system were 96 % and 99 %, respectively, at an influent OLR as high as 50 kg COD m-3 day-1. The maximum methane percentage in the UASB reactor was 82 % while the methane percentage was zero in UA/ANSB reactor for the aforementioned OLR at the end of steady-state conditions. NH4-N removal efficiency of the aerobic reactor was 90% while anaerobic ammonia oxidation was measured as 99 % in the anoxic reactor. The denitrification efficiency was 99% in the same reactor. Total TN removal of the whole system was 99 %. © Taylor & Francis, 2008.

A bacterium, strain BC, was isolated from a benzene-degrading chlorate-reducing enrichment culture. Strain BC degrades benzene in conjunction with chlorate reduction. Cells of strain BC are short rods that are 0.6 μm wide and 1 to 2 μm long, are motile, and stain gram negative. Strain BC grows on benzene and some other aromatic compounds with oxygen or in the absence of oxygen with chlorate as the electron acceptor. Strain BC is a denitrifying bacterium, but it is not able to grow on benzene with nitrate. The closest cultured relative is Alicycliphilus denitrificans type strain K601, a cyclohexanol-degrading nitrate-reducing betaproteobacterium. Chlorate reductase (0.4 U/mg protein) and chlorite dismutase (5.7 U/mg protein) activities in cell extracts of strain BC were determined. Gene sequences encoding a known chlorite dismutase (cld) were not detected in strain BC by using the PCR primers described in previous studies. As physiological and biochemical data indicated that there was oxygenation of benzene during growth with chlorate, a strategy was developed to detect genes encoding monooxygenase and dioxygenase enzymes potentially involved in benzene degradation in strain BC. Using primer sets designed to amplify members of distinct evolutionary branches in the catabolic families involved in benzene biodegradation, two oxygenase genes putatively encoding the enzymes performing the initial successive monooxygenations (BC-BMOa) and the cleavage of catechol (BC-C23O) were detected. Our findings suggest that oxygen formed by dismutation of chlorite can be used to attack organic molecules by means of oxygenases, as exemplified with benzene. Thus, aerobic pathways can be employed under conditions in which no external oxygen is supplied. Copyright © 2008, American Society for Microbiology. All Rights Reserved.

In the present study, lindane (1,2,3,4,5,6-hexachlorocyclohexane), methyl parathion (O-dimethylO-(4-nitro-phenyl) phosphorothioate) and carbofuran (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate) degradation potential of different enriched bacterial cultures were evaluated under various environmental conditions. Enriched cultures behaved differently with different pesticides. Degradation was more in a facultative anaerobic condition as compared to that in aerobic condition. A specific pesticide enriched culture showed maximum degradation of that pesticide irrespective of pesticides and environmental conditions. Lindane and endosulfan enriched cultures behaved almost similarly. Degradation of lindane by lindane enriched cultures was 75 � 3% in aerobic co-metabolic process whereas 78 � 5% of lindane degradation occurred in anaerobic co-metabolic process. Degradation of methyl parathion by methyl parathion enriched culture was 87 � 1% in facultative anaerobic condition. In almost all the cases, many intermediate metabolites were observed. However, many of these metabolites disappeared after 4-6 weeks of incubation. Mixed pesticide-enriched culture degraded all the three pesticides more effectively as compared to specific pesticide- enriched cultures. It can be inferred from the results that a bacterial consortium enriched with a mixture of all the possible pesticides that are present in the site seems to be a better option for the effective bioremediation of multi-pesticide contaminated site. Copyright � Taylor & Francis Group, LLC.

The surfactant nonylphenol (NP) is an endocrine-disrupting compound that is widely spread throughout the environment. Although environmental risk assessments are based on total NP concentrations, only the bioavailable fraction posses an environmental risk. The present study describes the bioavailability and biodegradability of NP over time in contaminated river sediment of a tributary of the Ebro River in Spain. The bioavailable fraction was collected with Tenax TA® beads, and biodegradation was determined in aerobic batch experiments. The presence of NP was analyzed chemically using gas chromatography-mass spectrometry and indirectly as estrogenic potency using an in vitro reporter gene assay (ERα-luc assay). Of the total extractable NP in the sediment, 95% ± 1.5% (mean ± standard error) desorbed quickly into the water phase. By aerobic biodegradation, the total extractable NP concentration and the estrogenic activity were reduced by 97% ±0.5% and 94% ± 2%, respectively. The easily biodegradable fraction equals the potential bioavailable fraction. Only 43 to 86% of the estrogenic activity in the total extractable fraction, as detected in the ERα-luc assay, could be explained by the present NP concentration. This indicates that other estrogenic compounds were present and that their bioavailability and aerobic degradation were similar to that of NP. Therefore, we propose to use NP as an indicator compound to monitor estrogenicity of this Ebro River sediment. To what extent this conclusion holds for other river sediments depends on the composition of the contaminants and/or the nature of these sediments and requires further testing. © 2008 SETAC.

A stable anoxic enrichment culture was obtained that degraded benzene with chlorate as an electron acceptor. The benzene degradation rate was 1.65 mM benzene per day, which is similar to reported aerobic benzene degradation rates but 20-1650 times higher than reported for anaerobic benzene degradation. Denaturing gradient gel electrophoresis of part of the 16S rRNA gene, cloning and sequencing showed that the culture had a stable composition after the seventh transfer. Five bacterial clones were further analyzed. Two clones corresponded to bacteria closely related to Alicycliphilus denitrificans K601. The three other clones corresponded to bacteria closely related to Zoogloea resiniphila PIV-3A2w, Mesorhizobium sp. WG and Stenotrophomonas acidaminiphila. DGGE analysis of cultures grown with different electron donors and acceptors indicated that the bacterium related to Alicycliphilus denitrificans K601 is able to degrade benzene coupled to chlorate reduction. The role of the other bacteria could not be conclusively determined. The bacterium related to Mesorhizobium sp. WG can be enriched with benzene and oxygen, but not with acetate and chlorate, while the bacterium related to Stenotrophomonas acidaminophila grows with acetate and chlorate, but not with benzene and oxygen. As oxygen is produced during chlorate reduction, an aerobic pathway of benzene degradation is most likely. © 2007 Federation of European Microbiological Societies.

A stable anoxic enrichment culture was obtained that degraded benzene with chlorate as an electron acceptor. The benzene degradation rate was 1.65 mM benzene per day, which is similar to reported aerobic benzene degradation rates but 20-1650 times higher than reported for anaerobic benzene degradation. Denaturing gradient gel electrophoresis of part of the 16S rRNA gene, cloning and sequencing showed that the culture had a stable composition after the seventh transfer. Five bacterial clones were further analyzed. Two clones corresponded to bacteria closely related to Alicycliphilus denitrificans K601. The three other clones corresponded to bacteria closely related to Zoogloea resiniphila PIV-3A2w, Mesorhizobium sp. WG and Stenotrophomonas acidaminiphila. DGGE analysis of cultures grown with different electron donors and acceptors indicated that the bacterium related to Alicycliphilus denitrificans K601 is able to degrade benzene coupled to chlorate reduction. The role of the other bacteria could not be conclusively determined. The bacterium related to Mesorhizobium sp. WG can be enriched with benzene and oxygen, but not with acetate and chlorate, while the bacterium related to Stenotrophomonas acidaminophila grows with acetate and chlorate, but not with benzene and oxygen. As oxygen is produced during chlorate reduction, an aerobic pathway of benzene degradation is most likely. © 2007 Federation of European Microbiological Societies.

A novel mixed bacterial culture was enriched from an endosulfan (6, 7, 8, 9, 10, 10 - hexachloro-1, 5, 5a, 6, 9, 9a-hexahydro-6, 9-methano-2, 3, 4-benzo (e) dioxathiepin-3-oxide) processing industrial surface soil. The cultures were successful in the degradation of aqueous phase endosulfan in both aerobic and anaerobic conditions. Using the cultures, endosulfan degradation in silty gravel with sand (GM) was examined via pilot scale reactor at an endosulfan concentration of 0.78 � 0.01 mg g- 1 of soil, and optimized moisture content of 40 � 1%. During operation, vertical spatial variability in endosulfan degradation was observed within the reactor. At the end of 56 days, maximum endosulfan degradation efficiency of 78 � 0.2% and 86.91 � 0.2% was observed in the top and bottom portion of the reactor, respectively. Both aerobic and anaerobic conditions were observed within the reactor. However, endosulfan degradation was predominant in anaerobic condition and the total protein concentration in the reactor was declined progressively down the soil depth. Throughout the study, no known intermediate metabolites of endosulfan reported by previous researchers were observed. Copyright � Taylor & Francis Group, LLC.

The surfactant nonylphenol (NP) is an endocrine-disrupting compound that is widely spread throughout the environment. Although environmental risk assessments are based on total NP concentrations, only the bioavailable fraction possess an environmental risk. The present study describes the bioavailability and biodegradability of NP over time in contaminated river sediment of a tributary of the Ebro River in Spain. The bioavailable fraction was collected with Tenax TA(R) beads, and biodegradation was determined in aerobic batch experiments. The presence of NP was analyzed chemically using gas chromatography-mass spectrometry and indirectly as estrogenic potency using an in vitro reporter gene assay (ER(alpha)-luc assay). Of the total extractable NP in the sediment, 95%+/-1.5% (mean +/- standard error) desorbed quickly into the water phase. By aerobic biodegradation, the total extractable NP concentration and the estrogenic activity were reduced by 97%+/-0.5% and 94%+/-2%, respectively. The easily biodegradable fraction equals the potential bioavailable fraction. Only 43 to 86% of the estrogenic activity in the total extractable fraction, as detected in the ER(alpha)-luc assay, could be explained by the present NP concentration. This indicates that other estrogenic compounds were present and that their bioavailability and aerobic degradation were similar to that of NP. Therefore, we propose to use NP as an indicator compound to monitor estrogenicity of this Ebro River sediment. To what extent this conclusion holds for other river sediments depends on the composition of the contaminants and/or the nature of these sediments and requires further testing.