Biodegradation of DDT by stimulation of indigenous microbial populations in soil with cosubstrates (original) (raw)
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African Journal of …, 2010
The re-introduction of dichlorodiphenyltrichloroethane (DDT) to control mosquitos was recommended by the World Health Organization in 2007. In this study, the potential for biodegradation of DDT by soil microorganisms through enrichment and isolation of DDT biodegraders from soils without a history of prior exposure to DDT was done. Microorganisms from cultivated and uncultivated soils grew in minimal media with DDT (100 ppm) as the only carbon source. Six bacteria coded as isolates 101, 102, 103, 104, 105 and 110 degraded DDT to l, l-dichloro-2, 2-bis (p-chlorophenyl) ethane (DDD). None of the isolates degraded DDT into l, l-dichloro-2,2-bis (p-chlorophenyl) ethylene (DDE). Degradation by the mixed culture of the six isolates was higher (82.63%) than that of any individual isolates whose range was 28.48 -58.08%. The identity of the isolates was determined through biochemical, morphological, physiological and molecular techniques. Isolate 101 was a member of the genus Bacillus; isolates 102 and 110 belonged to the genus Staphylococcus while isolates 103, 104 and 105 clustered with members of the genus Stenotrophomonas. This study showed that there are microorganisms in the soil that can degrade DDT and that the rate of degradation is dependent on the presence and numbers of microbes in the soil with the required degradative ability, environmental factors and access of the microbes to DDT.
Biodegradation of trichloroethylene and toluene by indigenous microbial populations in soil
Applied and environmental microbiology, 1993
The biodegradation of trichloroethylene (TCE) and toluene, incubated separately and in combination, by indigenous microbial populations was measured in three unsaturated soils incubated under aerobic conditions. Sorption and desorption of TCE (0.1 to 10 micrograms ml-1) and toluene (1.0 to 20 micrograms ml-1) were measured in two soils and followed a reversible linear isotherm. At a concentration of 1 micrograms ml-1, TCE was not degraded in the absence of toluene in any of the soils. In combination, both 1 ...
Research in Microbiology, 2000
Enrichment cultures on naphtha solvent were used to select aromatic hydrocarbon-degrading bacteria from a BTEX (benzene, toluene, ethylbenzene, xylene)-contaminated subsoil obtained from beneath a paint factory located in Milan, Italy. Fifteen isolated strains were studied for their different biodegradative capacities. Among these, 13 were able to grow on naphtha solvent. Ten were identified as Pseudomonas putida and three as Pseudomonas aureofaciens. Two other degraders were identified as Pseudomonas aeruginosa and Alcaligenes xylosoxidans subsp. denitrificans. Further molecular characterization of the isolates was carried out by randomly amplified polymorphic DNA analysis to ascertain that all the studied strains belonged to different haplotypes. The isolates were characterized for the presence of genes encoding for toluene dioxygenase, xylene monooxygenase and catechol 2,3-dioxygenase by polymerase chain reaction analysis and by Southern analysis. P. putida strain CM23, which showed homology with xylA,M, xylE and todC1C2BA genes, possessed multiple pathways which enabled the strain to grow on benzene, toluene and m-xylene.
PLOS One, 2012
Bacteria were identified associated with biodegradation of aromatic pollutants biphenyl, benzoate, and naphthalene in a long-term polychlorinated biphenyl-and polyaromatic hydrocarbon-contaminated soil. In order to avoid biases of culturebased approaches, stable isotope probing was applied in combination with sequence analysis of 16 S rRNA gene pyrotags amplified from 13 C-enriched DNA fractions. Special attention was paid to pyrosequencing data analysis in order to eliminate the errors caused by either generation of amplicons (random errors caused by DNA polymerase, formation of chimeric sequences) or sequencing itself. Therefore, sample DNA was amplified, sequenced, and analyzed along with the DNA of a mock community constructed out of 8 bacterial strains. This warranted that appropriate tools and parameters were chosen for sequence data processing. 13 C-labeled metagenomes isolated after the incubation of soil samples with all three studied aromatics were largely dominated by Proteobacteria, namely sequences clustering with the genera Rhodanobacter Burkholderia, Pandoraea, Dyella as well as some Rudaea-and Skermanella-related ones. Pseudomonads were mostly labeled by 13 C from naphthalene and benzoate. The results of this study show that many biphenyl/benzoate-assimilating bacteria derive carbon also from naphthalene, pointing out broader biodegradation abilities of some soil microbiota. The results also demonstrate that, in addition to traditionally isolated genera of degradative bacteria, yet-to-be cultured bacteria are important players in bioremediation. Overall, the study contributes to our understanding of biodegradation processes in contaminated soil. At the same time our results show the importance of sequencing and analyzing a mock community in order to more correctly process and analyze sequence data.
Microbial Ecology, 1995
The unsaturated subsurface (vadose zone) receives significant amounts of hazardous chemicals, yet little is known about its microbial communities and their capacity to biodegrade pollutants. Trichloroethylene (TCE) biodegradation occurs readily in surface soils; however, the process usually requires enzyme induction by aromatic compounds, methane, or other cosubstrates. The aerobic biodegradation of toluene and TCE by indigenous microbial populations was measured in samples collected from the vadose zone at unpolluted and gasoline-contaminated sites. Incubation at field moisture levels showed little activity on either TCE or toluene, so samples were tested in soil suspensions. No degradation occurred in samples suspended in water or phosphate buffer solution; however, both toluene and TCE were degraded in samples suspended in mineral salts medium. TCE degradation depended on toluene degradation, and little loss occurred under sterile conditions. Studies with specific nutrients showed that addition of ammonium sulfate was essential for degradation, and addition of other mineral nutrients further enhanced the rate. Additional studies with vadose sediments amended with nutrients showed similar trends to those observed in sediment suspensions. Initial rates of biodegradation in suspensions were faster in uncontaminated samples than in gasolinecontaminated samples, but the same percentages of chemicals were degraded. Biodegradation was slower and less extensive in shallower samples than deeper samples from the uncontaminated site. Two toluene-degrading organisms isolated from a gasoline-contaminated sample were identified as Corynebacterium variabilis SVB74 and Acinetobacter radioresistens SVB65. Inoculation with 106 ceils of C. variabilis ml-I of soil solution did not enhance the rate of degradation above that of the indigenous population. These results indicate that mineral nutrients limited the rate of TCE and toluene degradation by indigenous populations and that no additional benefit was derived from inoculation with a toluene-degrading bacterial strain.
Biodegradation of Aliphatic Chlorinated Hydrocarbon (PCE, TCE and DCE) in Contaminated Soil
2006
Soil bottles and soil slurry experiments were conducted to investigate the effect of some additives on the aerobic and anaerobic biodegradation of chlorinated aliphatic hydrocarbons; tetrachloroethylene (PCE), trichloroethylene (TCE) and dichloroethylene (DCE) in a contaminated soil from Startvätten AB Linköping Sweden. For the aerobic degradation study the soil sample was divided into two groups, one was fertilised. The two groups of soil in the experimental bottles were treated to varying amount of methane in pairs. DCE and TCE were added to all samples while PCE was found in the contaminated soil. Both aerobic and anaerobic experiments were conducted. For aerobic study air was added to all bottles to serve as electron acceptor (oxygen). It was observed that all the samples showed a very small amount of methane consumption while the fertilised soil samples showed more oxygen consumption. For the chlorinated compounds the expected degradation could not be ascertained since the control and experimental set up were more or less the same. For the anaerobic biodegradation study soil slurry was made with different media i.e. basic mineral medium (BM), BM and an organic compound (lactate), water and sulphide, phosphate buffer and sulphide and phosphate buffer, sulphide and ammonia. To assure anaerobic conditions, the headspace in the experimental bottles was changed to N 2 /CO 2. As for the aerobic study all the samples were added DCE and TCE while PCE was found in the contaminated soil. The sample without the soil i.e. the control was also given PCE. It was observed that there was no clear decrease in the GC peak area of the pollutants in the different media. The decrease in GC peak area of the pollutants could not be seen, this may be so because more susceptible microorganisms are required, stringent addition of nutrients and to lower the risk of the high concentration of PCE and petroleum products in the soil from Startvätten AB.
Applied and …, 2008
A bacterium designated strain BD-a59, able to degrade all six benzene, toluene, ethylbenzene, and o-, m-, and p-xylene (BTEX) compounds, was isolated by plating gasoline-contaminated sediment from a gasoline station in Geoje, Republic of Korea, ...
Detection and quantification of degradative genes in soils contaminated by toluene
FEMS Microbiology Ecology, 2000
A method based on the polymerase chain reaction (PCR) was developed for a rapid and specific detection of toluene degradative genes in soil. The xylE gene coding for catechol 2,3-dioxygenase was chosen as a target gene. The detection threshold was evaluated in microcosms using a sterilized standard soil inoculated with various amounts of a degradative strain of Pseudomonas putida (mX). The extracted DNA was used as a template to amplify the xylE gene. PCR followed by hybridization with an internal probe allowed us to detect 10' bacteria per g of soil. In polluted soils, quantification of target DNA by competitive PCR was compared with enumeration of degradative microflora. This molecular method appeared to be rapid, sensitive and more suitable than the microbiological approach to estimate the biodegradative potential of a polluted soil.
E3S web of conferences, 2024
Dichloro Diphenyl Trichloroethane (DDT) is an organochlorine insecticide that are largely used on agriculture and health sectors. DDT is an organic pollutant that are difficult to be dissolved and tend to survive in the environment for a long time because it is highly stable and persistent. DDT insecticide residue is still discovered in the soil even though its utilization has been stopped years ago and still negatively impacting human life and the environment through bio accumulation and bio magnification. Bioremediation is a potential method to remove recalcitrance compound such as DDT. The objective of this study is to gather and analyze information on DDT degradation by bacteria consortium with co-substrate addition. Pseudomonas putida and Pseudomonas stutzeri bacteria consortium were utilized to remediate DDT with glucose, sucrose, and yeast extract as cosubstrates. During 72 hours of observation, the three co-substrates namely yeast extract, glucose, and sucrose are able to degrade 75%, 56% and 39.55% of 10 ppm DDT. Yeast is the most ideal co-substrate to assist bacteria consortium growth and to degrade DDT. The implementation of pilot scale land treatment bioremediation is planned to be at 50m 3 , with dimension of 20m length, 5m wide, and 0.5m high. The efficiency of the removal reached 90% with 67 hours of detention time.
Journal of Chemical Technology & Biotechnology, 2013
BACKGROUND: This study focused on the simultaneous removal of BTEX (benzene, toluene, ethylbenzene, and xylenes) and CAHs (chlorinated aliphatic hydrocarbons, represented by cis-DCE (cis-1,2-dichloroethylene) and TCE (trichloroethylene) mixture from soil, using an indigenous BTEX-adapted bacterium identified as Pseudomonas plecoglossicida. CAHs can be aerobically cometabolized by microbial oxygenases induced during the bacterial growth on such primary substrates as toluene and ortho-xylene. RESULTS: The bioremoval extent of BTEX/CAHs mixture varied, depending on the experimental conditions. As the ratio of BTEX to CAHs concentration was changed from 4 to 20, the bioremoval of both BTEX and CAHs decreased. The increase of initial BTEX concentration, from 200 to 1000 ppm, increased the microorganism lag phase and correspondingly prolonged the bioremoval process but decreased the bioremoval efficiency. The cometabolism of CAHs, when toluene and/or BTEX were provided as growth substrate, was significantly higher compared with other treatments without toluene. The BTEX/CAHs mixture removal between sterile and non-sterile soils revealed removal by the inoculant to be the major removal mechanism for the mixture. CONCLUSION: A mixture of BTEX, cis-DCE, and TCE in soil was simultaneously removed by P. plecoglossicida under aerobic conditions. The results obtained help to enhance the applicability of bioremediation technology to mixed wastes contaminated sites.