Influence of hydroxypropyl-beta-cyclodextrin (HPCD) on the bioavailability and biodegradation of pyrene

It is well known that the limited aqueous solubilities of polycyclic aromatic hydrocarbons (PAH) often reduce their bioavailability to bacterial populations. The objective of this study was to test the impact of a solubility-enhancement reagent, hydroxypropyl-beta-cyclodextrin (HPCD), on the bioavailability and biodegradation of pyrene. No measurable loss of pyrene occurred for the control vials throughout the first 22 weeks of the experiment, indicating the absence of mass loss via abiotic transformation and volatilization. The vials containing pyrene and the degrader isolate (Burkholderia CRE 7), but no HPCD, also exhibited no measurable loss of pyrene throughout the experiment. Conversely, biodegradation of pyrene appears to have been initiated after approximately 15 weeks for the vials containing 10(4) mg l(-1) HPCD. By the end of the experiment, approximately 14% (w/w) of the pyrene was biodegraded in the presence of HPCD. These results indicate that HPCD may be useful for enhancing the bioavailability and biodegradation of pyrene and other PAHs.     

Source and transport of tricresyl phosphate (TCP) isomers in Kurose river basin

Atmospheric tricresyl phosphate (TCP) isomers in Kurose river basin were determined. The concentrations of o-TCP and m-TCP were 0.13 and 0.09 ng m⁻³, respectively, while p-TCP was scarcely detected. Exhaust gases from motorcycles and automobiles were main sources for TCP isomers in the atmosphere. Exhaust gas from incinerator also contributes to atmospheric concentration of TCP isomers. Most of the TCP isomers could be estimated to be sorbed to particles, due to their low vapor pressures. The concentrations of TCP isomers were relatively high in soils collected from an open storage yard of waste PVC and near the highway and greenhouse of agricultural film. On the other hand, the concentrations were negligibly small in soil collected from the forest except for the silt-clay fraction in the soil. Dry deposition fluxes of o-TCP and m-TCP from the atmosphere was 0.2 and 0.04 μg m⁻² d⁻¹, respectively. Wet deposition flux of TCP isomers during one rainfall exceeded occasionally the dry deposition flux for two weeks. TCP isomers accumulated in soil were discharged into river by precipitation event. Their concentrations increased with an increase in river flow, characteristic of a non-point source of TCP isomers.     

混合菌降解模拟聚乙烯醇(PVA)废水性能研究

从纺织废水污泥中筛选出了具有PVA降解能力的混合菌B07.通过正交实验得出其降解PVA的最佳条件:温度为35℃,pH为7,氮源为牛肉膏.在此条件下,B07对PVA1799模拟废水处理96 h时COD的去除率达64%.同时考察了PVA聚合度和醇解度对其降解性能的影响,结果表明,PVA聚合度越大,醇解度越高,其降解效率越差...     

纺锤芽孢杆菌(Bacillus fusiformis)降解萘的特性及动力学

在前期研究中发现,纺锤芽孢杆菌(Bacillus fusiformis,BFN)可以用于降解水溶液的萘,为了解其降解过程,发现BFN菌生长量随着溶液中的萘的含量增加而提高。其中,萘的含量分别是30、50、100和200 mg/L时,BFN的生物量OD600值分别为0.057、0.081、0.126和0.193;降解培养基溶液COD的去除率分别为59.4%、65.3%、69.2%和70.6%,说明BFN菌在生长的过程中利用萘作为碳源。同时,动力学拟合发现,对不同含量萘的降解过程都符合一级降解动力学方程,且BFN菌的生长过程满足逻辑斯蒂方程。扫描电镜图表明,BFN菌在萘的存在下生长得更好。紫外光谱显示波长为276 nm的萘的吸收峰在降解后下降很多。红外光谱数据则表明,降解液中有2组新的吸收峰出现:一组出现在2 878、2 930和2 968 cm-1处,说明在萘的降解过程中有新的羧酸类生成;另一组出现在3 438、3 667和3 731 cm-1处有新的酚类物质生成。     

Isolation and identification of intermediates from biodegradation of low chlorinated biphenyls (Delor-103)

Microorganism Pseudomonas species P2 metabolizes polychlorinated biphenyls (PCBs) and biphenyl, producing the whole spectrum of intermediates, among them coloured intermediates, which are suitable for the monitoring of PCBs degradation by optical sensors. Knowledge of chemical structures and conditions of development of colour metabolites is necessary for application of optical analytical methods. The main goal of this work was the isolation and identification of intermediates from the biodegradation of the mixture of low chlorinated biphenyls (Delor-103), which is based on the solid phase extraction (SPE) of the whole mixture using LiChrolut EN cartridges, then silylation of the extract as one way to the identification of one part of intermediates by GC-MS, and acetylation of the extract as a way for the further concentration and analysis of more polar chlorobiphenylols and chlorobiphenyldiols. The combination of SPE and following acetylation allows to obtain chlorobiphenylols and chlorobiphenyldiols as an almost pure fraction. The acetylation method could be also used instead SPE procedure with the same final concentration effect. Using the simulation mass spectrometry program, two new compounds, dihydrodihydroxytrichloro- and tetrahydrodihydroxytrichlorobiphenyl, as silylderivatives, were identified.     

Effect of ultrasonication and Fenton oxidation on biodegradation of bis(2-ethylhexyl) phthalate (DEHP) in wastewater sludge

The presence of bis(2-ethylhexyl) phthalate (DEHP) and its metabolites, i.e. 2-ethylhexanol, 2-ethylhexanal, and 2-ethylhexanoic acid in wastewater sludge (WWS) were investigated during aerobic digestion and Bacillus thuringiensis (Bt)-based fermentation of WWS. Ultrasonication and Fenton oxidation pre-treatment was applied to improve biodegradability of WWS and bioavailability of the target compounds for digestion and fermentation. DEHP and 2-ethylhexanoic acid were observed at higher concentration, meanwhile 2-ethylhexanol and 2-ethylhexanal were observed at lower concentration in WWS. After 20-day aerobic digestion, DEHP removal was 72%, 89%, and 85%, and 2-ethylhexanoic acid removal was 71%, 84%, 79%, respectively for raw, ultrasonicated, and Fenton-oxidized sludges. Bt was found to degrade DEHP, leading to DEHP removal of 21%, 40%, and 30%, respectively for raw, ultrasonicated, and Fenton-oxidized sludges in the fermentation. The results suggested that aerobic stabilization and Bt-based fermentation can remove the phthalates, and pre-treatment of WWS was also effective in improvement of DEHP biodegradation. Hence, Bt-based biopesticide production from WWS can be applied safely when taking into consideration the phthalate contaminants.     

PLA对土壤微生物生长的影响及PLA的生物降解性

从不同土壤环境中筛选出的4类不同土壤微生物91株,分别标记为细菌、固氮菌、分解纤维素菌和放线菌。然后通过将定量的聚乳酸（PLA）分别加入对应液态培养基中,恒温（30℃）摇床培养,连续测定这4类不同的土壤微生物对PLA的降解性能以及该种聚合物对各种微生物生长的影响。结果表明,虽然在自然界中PLA的降解率比较高,但不同类型的土壤微生物对PLA的降解性能却存在明显个体差异。在测试期内,放线菌对于PLA的总降解率最高;而细菌中RB-4的日降解率最高,达到3%左右;纤维分解菌HX-8及固氮菌RG-28的日降解率能达到2.4%。PLA降解产物对于细菌及纤维分解菌的抑制性普遍较强。     

Fate of mutagenicity produced during anaerobic biodegradation of the herbicide chlornitrofen (CNP)

The mutagenicity of chlornitrofen (CNP)-containing solutions has been reported to increase during anaerobic biodegradation. In the present study, the fate of this increased mutagenicity under subsequent aerobic and anaerobic incubation conditions was investigated using two Salmonella tester strains, YG 1024 (a frameshift-detecting strain) and YG 1029 (a base-pair-substitution-detecting strain). Mutagenicity for both YG 1024 and YG 1029 strains increased during nine-day anaerobic biodegradation. During subsequent anaerobic incubation, the increased mutagenicity decreased gradually for YG 1029 but did not change significantly for YG 1024. By contrast, the increased mutagenicity decreased rapidly after the conversion to aerobic incubation for both YG 1024 and YG 1029 strains. The rapid decrease in mutagenicity during aerobic incubation was due to decreases, not only in an identified mutagenic metabolite (CNP-amino) but also in unidentified mutagenic metabolites.     

Behaviour and biodegradation of sulfonamides (p-TSA, o-TSA, BSA) during drinking water treatment

Three sulfonamides -para-toluenesulfonamide (p-TSA), ortho-toluenesulfonamide (o-TSA) and benzenesulfonamide (BSA) - have recently been detected in groundwater within a catchment area of one drinking water treatment plant (DWTP), which is located downstream of a former sewage farm. The degradation pathways of p-TSA, o-TSA and BSA were investigated during drinking water treatment with incubation experiments and an experimental filter. Incubation experiments showed that p-TSA is removed during the treatment by microbiological processes. Removal of p-TSA is performed by adapted microorganisms only present in polluted groundwater. The elimination in an experimental filter of 1.6m length applying filtration velocities from 2 to 6 m h(-1) was approximately 93% of p-TSA. The microbial degradation rates in the incubation experiment were approximately 0.029 microg l(-1) h(-1) (zero order reaction). In the experimental filter, the reaction rate constants were around 0.0063 s(-1) for all filtration velocities (1st order reaction). Drinking water treatment does not reduce the concentration of o-TSA and BSA under conditions encountered in Berlin. p-TSA, o-TSA and BSA were only measured in the low microg l(-1) concentrations range in the purified water.     

Anaerobic biodegradation of weathered polychlorinated biphenyls (PCBs) in contaminated sediments of Porto Marghera (Venice Lagoon,Italy)

The biodegradation of weathered polychlorinated biphenyls (PCBs) (mono and di-chlorinated biphenyls along with PCBs partially ascribed to Aroclor 1242 and 1254) occurring at 1.5-2.5 mg/kg in three different sediments collected from the Porto Marghera contaminated area of Venice Lagoon (Italy) was reported in this study. Strictly anaerobic, slurry microcosms consisting of sediments suspended (at 25% v/v) in a marine salt medium, lagoon water or lagoon water supplemented with NaHCO3 and Na2S were developed and monitored for PCB transformation, sulfate consumption and methane (CH4) production for 6 months. A marked depletion of highly chlorinated biphenyls along with the accumulation of low-chlorinated, often ortho-substituted biphenyls was observed in the biologically active microcosms, where a remarkable consumption of sulfate and/or a significant production of CH4 were also detected. Notably, a more extensive PCB transformation was observed in the microcosms developed with site water (both without or with NaHCO3 plus Na2S), where both the initial concentration of sulfate and sulfate consumption were five fold-higher than in the corresponding microcosms with salt medium. These data indicate that weathered PCBs of the three contaminated sediments of Porto Marghera utilized in this study can undergo reductive dechlorination, probably mediated by indigenous sulfate-reducing and/or methanogenic bacteria.     

Anaerobic biodegradation of DDT residues (DDT, DDD, and DDE) in estuarine sediment.

The potential for anaerobic biodegradation of 1,1,1-trichloro-2,2-bischlorophenylethane (DDT), 1,1-dichloro-2,2,-bischlorophenylethane (DDD), and dichlorodiphenylchloroethylene (DDE) in anoxic sediment slurries collected from the Keelung River was investigated in this study. o,p'- and p,p'-DDT were dechlorinated to o,p'- and p,p'-DDD, respectively, and then transformed to other compound(s). 1-Chloro-2,2-bis (p-chlorophenyl) ethylene (DDMU) and trace amount of dichlorobenzophenone (DBP) were detected in sediment slurries amended with p,p'-DDT or p,p'-DDD. DDMU was also detected in sediment slurries amended with p,p'-DDE. The relative transformation rates for both o,p'- and p,p'-isomers of DDT, DDD, and DDE were DDT>DDD>DDE. Re-addition of DDT, DDD, or DDE to the sediment slurries after initial removal enhanced the respective dechlorination rates. The transformation rates of the p,p'-isomers of both DDT and DDD were faster than those of the respective o,p'-isomers. p,p'-DDT dechlorination in the p,p'-DDT-adapted sediment slurries were inhibited by the addition of molybdate, or molybdate plus sulfate, but not inhibited by the addition of sulfate. Addition of bromoethane-sulfonic acid (BESA) slightly inhibited p,p'-DDT dechlorination. Non-adapted sediment slurries lost the ability to dechlorinate pentachlorophenol during adaptation to p,p'-DDT. p,p'-DDD was the major transformation product of p, p'-DDT in 3,4,4',5-tetrachlorobiphenyl-adapted sediment slurries, which suggested that the microbial community in the 3,4,4',5-CB-adapted sediment was unable to remove chlorine from the aromatic rings of p,p'-DDT.     

Chlorinated pesticides (2,4-D and DDT) biodegradation at high concentrations using immobilized Pseudomonas fluorescens

Degradation of two chlorinated pesticides (2,4-D and DDT) using a 54-mL glass column packed with tezontle (a low-cost basaltic scoria) was tested. Bacteria were cultured in YPG (yeast, peptone, and glucose) liquid medium at 32 degrees C. The rich medium was pumped during 24 h through the column to inoculate it. Later, the wasted medium was discharged and the pesticide added. Optical densities, TOC, and pesticide concentration were determined. Pesticide removals for 2,4-D (with initial concentration between 100 and 500 mg/L) were about 99%. DDT removal (at initial concentration of up to 150 mg/L) was as high as 55-99%. TOC removals for 2,4-D was in the 36-87% interval, whereas for DDT they were as high as 36-78%.     

Concurrent nitrate and Fe(III) reduction during anaerobic biodegradation of phenols in a sandstone aquifer

The biodegradation of phenols (5, 60, 600 mg l⁻¹) under anaerobic conditions (nitrate enriched and unamended) was studied in laboratory microcosms with sandstone material and groundwater from within an anaerobic ammonium plume in an aquifer. The aqueous phase was sampled and analyzed for phenols and selected redox sensitive parameters on a regular basis. An experiment with sandstone material from specific depth intervals from a vertical profile across the ammonium plume was also conducted. The miniature microcosms used in this experiment were sacrificed for sampling for phenols and selected redox sensitive parameters at the end of the experiment. The sandstone material was characterized with respect to oxidation and reduction potential and Fe(II) and Fe(III) speciation prior to use for all microcosms and at the end of the experiments for selected microcosms.The redox conditions in the anaerobic microcosms were mixed nitrate and Fe(III) reducing. Nitrate and Fe(III) were apparently the dominant electron acceptors at high and low nitrate concentrations, respectively. When biomass growth is taken into account, nitrate and Fe(III) reduction constituted sufficient electron acceptor capacity for the mineralization of the phenols observed to be degraded even at an initial phenols concentration of 60 mg l⁻¹ (high) in an unamended microcosm, whereas nitrate reduction alone is unlikely to have provided sufficient electron acceptor capacity for the observed degradation of the phenols in the unamended microcosm.For microcosm systems, with solid aquifer materials, dissolution of organic substances from the solid material may occur. A quantitative determination of the speciation (mineral types and quantity) of electron acceptors associated with the solids, at levels relevant for degradation of specific organic compounds in aquifers, cannot always be obtained. Hence, complete mass balances of electron acceptor consumption for specific organic compounds degradation are difficult to confine. For aquifer materials with low initial Fe(II) content, Fe(II) determinations on solids and in aqueous phase samples may provide valuable information on Fe(III) reduction. However, in microcosms with natural sediments and where electron acceptors are associated with the sediments, complete mass-balances for substrates and electron acceptors are not likely to be obtained.     

2,4-Dichlorophenoxyacetic acid (2,4-D) biodegradation in river sediments of Northeast-Scotland and its effect on the microbial communities (PLFA and DGGE)

A bench-scale study was conducted to investigate 2,4-D biodegradation rates at different concentrations (10, 100 and 1000 microg per gram of dry weight) in distinct sediments samples collected on the River Ythan, Northeast-Scotland. Mineralisation of 14C 2,4-D occurred mostly within 30 days for all tested concentrations with a degradation rate ranging from 5 to 750 microg d(-1). Biodegradation rates were affected by the biological and biochemical characteristics of the indigenous microbial community in the studied sediments rather than factors such as compound bioavailability and/or toxicity. PLFA-profiling provided evidences of the effect of 2,4-D amendments on the microbial communities and DGGE-profiling showed changes in the genetic potential of the microbial populations which might affect metabolic characteristics of the sediment. PLFAs biomarkers suggested that the pathway of alpha-ketoglutarate-dependent dioxygenase was the main route of 2,4-D biodegradation. This pathway is commonly found in microorganisms of the beta-subdivision of proteobacteria.     

Transformation and Ecotoxicity of Carbamic Pesticides in Water (5 pp)

Background N-methylcarbamate insecticides are widely used chemicals for crop protection. This study examines the hydrolytic and photolytic cleavage of benfuracarb, carbosulfan and carbofuran under natural conditions. Their toxicity and that of the corresponding main degradation products toward aquatic organisms were evaluated. Methods Suspensions of benfuracarb, carbosulfan and carbofuran in water were exposed to sunlight, with one set of dark controls, for 6 days, and analyzed by 1H-NMR and HPLC. Acute toxicity tests were performed on Brachionus calyciflorus, Daphnia magna, and Thamnocefalus platyurus. Chronic tests were performed on Pseudokirchneriella subcapitata, and Ceriodaphnia dubia. Results and Discussion Under sunlight irradiation, benfuracarb and carbosulfan gave off carbofuran and carbofuran-phenol, while only carbofuran was detected in the dark experiments. The latter was degraded to phenol by exposure to sunlight. Effects of pH, humic acid and KNO3 were evaluated by kinetics on dilute solutions in the dark and by UV irradiation, which evidenced the lability of the pesticide at pH 9. All three pesticides and phenol exhibited acute and higher chronic toxicity towards the aquatic organisms tested. Conclusion Investigation on the hydrolysis and photolysis of benfuracarb and carbosulfan under natural conditions provides evidence concerning the selective decay to carbofuran and/or phenol. Carbofuran is found to be more persistent and toxic. Recommendations and Outlook The decay of benfuracarb and carbosulfan to carbofuran and the relative stability of this latter pesticide account for many papers that report the detection of carbofuran in water, fruits and vegetables.     

Determination of naturally occurring MTBE biodegradation by analysing metabolites and biodegradation by-products

Methyl tert-butyl ether (MTBE) is one of the main additives in gasoline. Its degradation is known to be difficult in natural environments. In this study, significant MTBE degradation is demonstrated at a contaminated site in Leuna (eastern Germany). Since the extent of the plume appeared to be constant over the last 5 years, an extended study was performed to elucidate the degradation processes. Special attention was paid to the production, accumulation and degradation of metabolites and by-products. Groundwater samples from 105 monitoring wells were used to measure 20 different substances. During the degradation process, several intermediates such as tert-butyl alcohol (TBA), tert-butyl formate, formate and lactate were produced. However, the potentially carcinogenic by-product methacrylate was not detected in several hundred samples. At the Leuna site, MTBE degradation occurred under microaerobic conditions. In contrast to hydrocarbons and BTEX, there was no evidence for anaerobic MTBE degradation. Among the degradation products, TBA was found to be a useful intermediate to identify MTBE degradation, at least under microaerobic conditions. TBA accumulation was strongly correlated to MTBE degradation according to the kinetic properties of both degradation processes. Since maximum degradation rates (v(max)) and k(m) values were higher for MTBE (v(max)=2.3 mg/l/d and k(m)=3.2 mg/l) than for TBA (v(max)=1.35 mg/l/d and k(m)=0.05 mg/l), TBA significantly accumulated as an intermediate by-product. The field results were supported by bench scale model aquifer experiments.     

Transformation products of 2-benzoxazolinone (BOA) in soil

Three degradation experiments were performed to examine the formation of transformation products from 2-benzoxazolinone (BOA) in different soil types and concentrations. In two experiments using BOA in low concentration (400 microgkg(-1)) only one unidentified transformation product was found, whereas in the degradation experiment in high concentration (400 mgkg(-1)) several metabolites occurred. Two of these metabolites, 2-amino-(3H)-phenoxazin-3-one (APO); and 2-acetylamino-(3H)-phenoxazin-3-one (AAPO) were synthesized to prove their identity. This is the first time that the successive formation of these types of compounds from BOA is shown in soil. A number of other APO related transformation products were detected and provisionally characterized. The formation of APO, which is a much more biologically active compound than BOA, and the concurrent formation of a number of other APO-related metabolites in soil underline the importance of performing transformation studies as part of the evaluation of the effect of allelochemicals on weeds and soil-borne diseases.     

Influence of aggregated particles on biodegradation activities for dimethylarsinic acid (DMA) in Lake Kahokugata

Aquatic arsenic cycles mainly depend on microbial activities that change the arsenic chemical forms and influence human health and organism activities. The microbial aggregates degrading organic matter are significantly related to the turnover between inorganic arsenic and organoarsenic compounds. We investigated the effects of microbial aggregates on organoarsenic mineralization in Lake Kahokugata using lake water samples spiked with dimethylarsinic acid (DMA). The lake water samples converted 1 μmol L⁻¹ of DMA to inorganic arsenic for 28 d only under anaerobic and dark conditions in the presence of microbial activities. During the DMA mineralization process, organic aggregates >5.0 μm with bacterial colonization increased the densities. When the organic aggregates >5.0 μm were eliminated from the lake water samples using filters, the degradation activities were reduced. DMA in the lake water would be mineralized by the microbial aggregates under anaerobic and dark conditions. Moreover, DMA amendment enhanced the degradation activities in the lake water samples, which mineralized 50 μmol L⁻¹ of DMA. The DMA-amended aggregates >5.0 μm completely degraded 1 μmol L⁻¹ of DMA with a shorter incubation time of 7 d. The supplement of KNO₃ and NaHCO₃ to lake water samples also shortened the DMA-degradation period. Presumably, the bacterial aggregates involved in the chemical heterotrophic process would contribute to the DMA-biodegradation process in Lake Kahokugata, which is induced by the DMA amendment.