Showing papers on "Microbial biodegradation published in 2002"

Biotechnology and bioremediation: successes and limitations.

Abstract: With advances in biotechnology, bioremediation has become one of the most rapidly developing fields of environmental restoration, utilizing microorganisms to reduce the concentration and toxicity of various chemical pollutants, such as petroleum hydrocarbons, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, phthalate esters, nitroaromatic compounds, industrial solvents, pesticides and metals. A number of bioremediation strategies have been developed to treat contaminated wastes and sites. Selecting the most appropriate strategy to treat a specific site can be guided by considering three basic principles: the amenability of the pollutant to biological transformation to less toxic products (biochemistry), the accessibility of the contaminant to microorganisms (bioavailability) and the opportunity for optimization of biological activity (bioactivity). Recent advances in the molecular genetics of biodegradation and studies on enzyme-tailoring and DNA-shuffling are discussed in this paper.

Nutritional constraints to degradation of polycyclic aromatic hydrocarbons in a simulated rhizosphere

Abstract: An industrially polluted soil (3.1 g PAH kg−1) was used to study C, N and P limitations to dissipation of polycyclic aromatic hydrocarbons (PAHs) in a model rhizosphere. Soil columns (50 cm3) were packed with soil and percolated daily with artificial root exudates (ARE) at 100 μg C g−1, 1 mM NH4NO3 or 1 mM NaH2PO4, or any double or triple combination of these for 30 days. At harvest, soil was analyzed for PAHs, and the numbers of total heterotrophic and PAH degrading bacteria estimated by an MPN technique. Dissipation of 3 and 4 ring PAHs was highest in soil receiving ARE+N, followed by the treatments with N+P and ARE+N+P. The complete treatment ARE+N+P had the highest dissipation of 5-ring PAHs. For both 5 and 6 ring PAHs most treatments resulted in increased concentrations at the end of the experiment, which was attributed to desorption of initially unextractable molecules. PAH degrading bacteria reached the highest numbers in the ARE+N+P treatment, followed by the treatment receiving only P, whereas total number of heterotrophs was elevated in the treatments ARE, P, ARE+N and ARE+N+P. Net PAH dissipation in soil was seemingly due to the two counteracting processes biodegradation and desorption. In the presence of ARE, the dissipation of higher molecular weight PAHs apparently involved microbial degradation and/or biotransformation through co-metabolism.

Isolation and initial characterization of a bacterial consortium able to mineralize fluorobenzene.

Abstract: Fluorinated compounds are known to be more resistant to microbial degradation than other halogenated chemicals. A microbial consortium capable of aerobic biodegradation of fluorobenzene (FB) as the sole source of carbon and energy was isolated by selective enrichment from sediments collected in a drain near an industrial site. A combination of three microbial strains recovered from the enriched consortium was shown to be necessary for complete FB mineralization. Two of the strains (F1 and F3) were classified by 16S rRNA analysis as belonging to the Sphingobacterium/Flavobacterium group, while the third (F4) falls in the beta-Proteobacteria group, clustering with Alcaligenes species. Strain F4 was consistently found in the liquid cultures in a much greater proportion than strains F1 and F3 (86:8:6 for F4, F1, and F3, respectively). Stoichiometric release of fluoride ions was measured in batch and fed-batch cultures. In batch cultures, the consortium was able to use FB up to concentrations of 400 mg liter(-1) and was able to utilize a range of other organic compounds, including 4-fluorophenol and 4-fluorobenzoate. To our knowledge this is the first time biodegradation of FB as a sole carbon source has been reported.

Biodegradation of Aliphatic Polyesters

Abstract: Introduction Distribution of Microorganisms Able to Degrade Four Representative Aliphatic Polyesters Degrading Microorganisms at Ambient Temperature (30 °C) Degrading Microorganisms at High Temperature (50 °C) Polyester Degrading Ability of Reference Cultures from Type Culture Collections Microbial Degradation of Poly(ethylene adipate) (PEA) PEA degradation by Penicillium sp. 14-3 PEA-degrading Enzyme Produced by Penicillium sp. 14-3 Hydrolysis of Aliphatic Polyesters by Commercial Lipases Aspects Affecting the Degradability of Polyesters by Rhizopus Lipase Microbial Degradation of PCL Microbial Degradation of PHB Microbial Degradation of PPL Microbial Degradation of PBS, PES, and PBS/A Microbial Degradation of PLA Micobial Degradation of Polycarbonate, Polyester Carbonate, Poly(ether-ester), and Copolyester Polycarbonate and Polyester Carbonate Poly(p-dioxanone) (PPDO) Poly(2-methylene-1,3,6-trioxocane) Aliphatic–Aromatic Copolyester Outlook and Perspectives Keywords: aliphatic polyester; microbial degradation

Microbial Aspects in Bioremediation of Soils Polluted by Polyaromatic Hydrocarbons

Abstract: Polyaromatic hydrocarbons (PAHs) are ubiquitous pollutants found in high concentrations at industrial sites associated with petroleum, coal tar, gas production and wood preservation industries. Due to their carcinogenic and mutagenic properties, PAHs are considered as environmental priority pollutants. They are stable and recalcitrant in soils as they are less easy to degrade than many other organic compounds. Though feasible, bioremediation of PAH-contaminated soils is seriously hampered by the low bioavailability of these compounds, making their removal a long and difficult process. Some PAH-degrading microorganisms seem however to be adapted to face the unfavourable physico chemical- properties of PAHs. Recent studies have shown that these peculiar organisms often belong to a discrete number of bacterial or fungal genera. In this review, both physico-chemical and metabolic aspects associated with the bacterial removal of PAHs from contaminated soils are discussed, as well as the perspectives for improving the associated biological technologies.

Biotransformations : bioremediation technology for health and environmental protection

Abstract: Preface. List of abbreviations. List of contributors. 1. Bioremediation of compounds hazardous to health and the environment: an overview (R. Brigmon, D. Camper, F. Stutzenberger). 2. Microbial degradation of polychlorinated biphenyls (PCBs) in the environment (W.-R. Abraham). 3. Biodegradation of fuel oils and lubricants: soil and water bioremediation options (S. Wilkinson, S. Nicklin, J.L. Faull). 4. Bioremediation technology for environmental protection through bioconversion of agro-industrial wastes (T.N. Lakhanpal). 5. Enzymatic transformations of xenobiotics of health and environmental concern (V.P. Singh). 6. Microbial degradation of chlorobenzoates (CBAs): biochemical aspects and ecological implications (G. Baggi). 7. Microbial degradation of insecticides: an assessment for its use in bioremediation (D.K. Singh). 8. Microbial variables for bioremediation of heavy metals from industrial effluents (R. Gupta, R.K. Saxena, H. Mohapatra, P. Ahuja). 9. Lactic acid bacteria in winemaking: influence on sensorial and hygienic quality (A. Lonvaud-Funel). 10. Microbial transformation of aflatoxins (T. Shantha, M. Archana). 11. Biotransformations of tannery wastes (V.P. Singh). 12. Oxidation of organic and inorganic sulfur compounds by aerobic heterotrophic marine bacteria (J.M. Gonzalez, et al.). 13. Lignin degradation by bacteria (A.P. Iyer, A. Mahadevan). 14. Microbial bioremediation of textile effluents (R.S. Upadhyay). 15. Biodegradation of diaryl esters: bacterial and fungal catabolism of phenylbenzoate and some of its derivatives (S. Schmidt). 16. Degradation of natural rubber products by Nocardia species (A. Tsuchii, Y. Tokiwa). 17. Sewage treatment systems: microbiological aspects (V.P. Singh, K. Bhatnagar). 18. Electro-physical properties of microbial cells during the aerobic metabolism of toxic compounds (O.V. Ignatov, S. Yu. Shchyogolev, V.D. Bunin, V.V. Ignatov). 19. Microbial degradation of sulfur compounds present in coal and petroleum (B.K. Gogoi, R.L. Bezbaruah). 20. Algae-dependent bioremediation of hazardous wastes (I. Kaur, A.K. Bhatnagar). 21. Some physiological characteristics of saprotrophic and ectomycorrhizal fungi producing sporophores on the urea-treated forest floor (T. Yamanaka). 22. Bioremediation of contaminated water bodies (B.K. Singh, V.P. Singh, M.N. Singh). 23. Biotransformations and biodegradation in extreme environments (A.V. Palumbo, et al.). 24. Bioremediation of hazardous ethylenebisdithiocarbamate (EBDC) fungicides (D.K. Singh). Index.

Molecular assessment of the potential for in situ bioremediation of PCBs from aquatic sediments

Abstract: Polychlorinated biphenyls (PCBs) are a family of xenobiotic compounds that are ubiquitous and oftentimes persistent environmental pollutants. As such, PCBs are a common target of sediment remediation efforts. Microbial degradation of sediment pollutants such as PCBs offers an environmentally sound and economically favorable alternative to conventional means of remediation such as dredging. This project describes the development of a PCR-based assay to determine the potential for PCB bioremediation by the resident microbial consortium in contaminated sediments. Using PCR and RT-PCR of DNA and RNA, respectively, extracted from aquatic sediments collected from the western basin of Lake Erie and one of its tributaries, we were able to amplify the bphA1 gene that encodes the large subunit of biphenyl dioxygenase. Since other studies have determined that the BphA1 gene product dictates PCB congener specificity, this assay may prove to be a useful screen for endemic catabolic activities for PCB mixtures in aquatic sediments.

Bioremediation of compounds hazardous to health and the environment: An overview

Abstract: Publisher Summary This chapter focuses on the fundamental microbial mechanisms (oxidative, reductive, and hydrolytic reactions) and associations in plant and microbial populations (competition, cross-feeding and commensalism), which may be essential to their success. Bioremediation of the chemicals in the soil depends on the activities of microbes in the soil, or in association with the root system. Chemical/physical properties of the chemical itself can influence the availability of the chemical to the microbe, or the susceptibility to degradative processes. Molecular alterations catalyzed by the microbial processes include oxidation, reduction, hydrolysis, de-esterification, dehalogenation, dealkylation, conjugation, and others. These processes usually result in a non-toxic chemical in the case of a pesticide, or in decreasing contamination levels of hazardous materials. Dissipation of pesticides in the soil involves several processes: volatilization, photodecomposition, leaching, adsorption, and microbial degradation. This chapter has been an overview of bioremediation processes, together with a few examples to illustrate the principles and efficacy of those processes.

Microbial degradation of insecticides: An assessment for its use in bioremediation

Abstract: Publisher Summary In soil, micro-organisms (bacteria, fungi, etc.) are primarily responsible for pesticide degradation. Thus, the microbial breakdown of insecticides is considered to be the most important catabolic reaction in soil. Microbes are degrading xenobiotic compounds/pesticides in the environment and use them for their normal metabolic processes as carbon or phosphorus source or consume the pesticides along with other source of food or energy. This bioprocess of microbes can be utilized for the development of pesticide decontamination and restoration of health of the environment. Hydrolytic enzymes, responsible for degradation of pesticides to non-toxic products in the environment can be developed for the future remedy for toxic compounds as bioremediation. Significant proportions of insecticides may form bound residues with the soil, which are not readily available to the plants and are often not very toxic to the biota. This may represent a mechanism by which the insecticide residues may persist for longer periods in soil and may be released only very slowly, and a relatively small proportion of these may be taken up by the plants and earthworms, and are responsible for the contamination of ecosystem.

Isotope fractionation of toluene: a perspective to characterise microbial in situ degradation.

Abstract: A concept to assess in situ biodegradation of organic contaminants in aquifers is presented. The alteration of the carbon isotope composition of contaminants along the groundwater flow path indicates microbial degradation processes and can be used as an indicator for in situ biodegradation. The Rayleigh equation was applied to calculate the percentage of the in situ biodegradation (B[%]) using the change in the isotopic composition of contaminants (Rt /R0) along the ground water flow path and a kinetic carbon isotope fractionation factor (α C) derived from defined biodegradation experiments in the laboratory. When the groundwater hydrology is known and a representative source concentration (C0) for a groundwater flow path can be determined, the extent of in situ biodegradation can be quantified.

Biodegradation of Polycarbonates

Abstract: Introduction Microbial Biodegradation of PEC and PPC Microbial Biodegradation of PBC and PHC Microbial Biodegradation of Polyester Carbonate (PBS/C) Enzymatic Degradation of Aliphatic Polycarbonates Enzymatic Synthesis of Polycarbonate Outlook and Perspectives Keywords: biodegradable plastic; aliphatic polycarbonate; aliphatic polyesters; microbial degradation; lipase; cholesterol esterase; biodegradability; phylogenetically diverse; hydrolysis; enzymatic degradation

Microbial degradation of chlorobenzoates (CBAs): Biochemical aspects and ecological implications

Abstract: Publisher Summary The behavior of chlorobenzoates (CBAs) in soils and waters has been carefully considered, as these compounds are used themselves as herbicides. The Chlorobenzoic acids from mono- to tri-substituted compounds, were shown susceptible to microbial attack, even if more chlorinated isomers and/or having chlorine atoms in ortho position were demonstrated more refractory to biodegradation. CBAs can be totally mineralized with stoichiometric release of the chlorine atoms, both in aerobic and anaerobic conditions, or can undergo only co-metabolic transformations giving dead-end products, which the other microorganisms could utilize for their growth. The bacterial strategies for CBA degradation, elucidated with pure cultures or in microbial consortia, turn around the detachment of chlorine atoms that may occur through: (i) oxygenolytic elimination in an early stage mediated by more or less specific 1,2- or 1,6-dioxygenases leading to the formation of catechol or chlorocatechols; (ii) spontaneous C1-release at a later stage, by lactonization of the ortho-ring fission product; (iii) initial dehalogenation through hydrolytic or oxidative reactions with the formation of corresponding hydroxy derivatives; and (iv) reductive dechlorinations, mostly occurring in anaerobic conditions, and on polychlorinated compounds, with the formation of the corresponding derivatives carrying n-1 chlorine substituents.

Biodegradation of Estrogens Using a Nitrifying Activated Sludge

Abstract: In this paper, the biodegradability of estrogens; estrone (E1), 17β-estradiol (E2), and ethynylestradiol (EE2) ; was evaluated using a nitrifying activated sludge (NAS) . NAS could degrade E1, E2, EE2 with the biodegradation rate constants, i.e.0.035h-1, 0.056h-1, 1.3h-1 respectively, indicating that E2 was the most biodegradable among the three estrogens.It should be noted that biodegradation of E2 produced E1, which was confirmed by a spike test on a reversed phase high performance liquid chromatography equipped with an electrochemical detector (HPLC-ECD) . An sequential reaction analysis where it was assumed that E2 was biodegraded to an unknown compound via E1 showed that E1 was firstly produced by biodegradation of E2. As for the unknown intermediates of E1 and EE2 were detected by HPLC-ECD. Based on the result that these electrochemically detectable compounds were eluted faster than the parent compounds, i.e. E1 and EE2, On the HPLC-ECD, it was suggested that more polar compounds containing phenolic group than the three estrogens were produced by NAS. Because significant decrease of the peak area of these compounds on the HPLC-ECD chromatogram was observed during biodegradation of E1 and EE2, it was suggested that NAS could cleavage phenolic group of E1 and EE2.

Microbial degradation of mussels removed from the surface of marine structures

Abstract: After being crushed, a net weight 218 kg of mussels was reduced to 120.5 kg by discharge of seawater from the shells. The sample containing some of broken shells was applied to the degradation by Bacillus sp. The initial weight of 120.5 kg was reduced to 82.5 kg after 76 h of microbial degradation. Concentrations of the produced carbon dioxide and ammonia showed peak values of 15,000 and 720 ppm after 12.5 and 58 h, respectively. At 12.5 h, temperature in the sample reached to 65 degrees Celsius by the fermentation temperature. The ratio of total amounts of carbon and nitrogen, C/N ratio, was 22.6 after 76 h. Some of the heavy metals and toxic chemical compounds, which cause environmental pollution, were analyzed in the sample for the recycle of compost. The concentrations of such compounds detected were much lower than those recommended by the Japanese Ministry of the Environment. Therefore, the recycling of compost seems to be legal and possible. The strain used in this experiment was identified as Bacillus subtilis subsp. subtilis based on the biochemical and physiological properties as well as the homology analysis for the partial sequences of 16S rDNA.

Biodegradation of Synthetic Compounds and Agro-Chemicals by Soil Microorganisms in Field Soils

Abstract: x近年制度化 しつつある土壌環境保全対策に向けて, 環境 修復技術の開発要請が高まりつつある. 毎年農薬散布を必 要 とする農耕地土壌中の微生物分解性 と残留性の検討は重 要な課題である. 2001年5月 に農薬等の化学物質の汚染か ら人の健康および環境 を保護す ることを目的とする\"残 留 性有機汚染物質(POPs)に 関す るス トックホルム条約\"に より12種 類の化合物(ア ル ドリン(殺 虫剤), ディル ドリ ン(殺 虫剤), エン ドリン(殺 虫剤), クロルデン(殺 虫剤), ヘプタクロル(殺 虫剤), トキサフェン(殺虫剤), マイレッ クス(殺 虫剤), ヘキサクロロベ ンゼン(殺 虫剤), PCB(絶 縁油, 熱媒体等), DDT(殺 虫剤), ダイオキシン類, フラ ン類)が 当面の規制対象 とな り, これらについては特に環 境動態を十分に把握することが国際的に強 く求められる状 況にある. 微生物は多様 な代謝機能 を備えてお り, 環境汚染物質を 分解する微生物は好気性細菌を中心に過去数十年間にわた り, Rhodococcus属, Sphingomonas属, Pseudomonas属, Burkholderia属, Comamonas属, Alcanivorax属, Bacillus 属, Arthrobacter属 等様々な分解菌が分離されてきている. これらの多 くが有機栄養生物であり, 合成有機化合物は電 子供与体 として, 酸素を電子受容体 としたオキシゲナーゼ 系の酸素添加酵素の共代謝(コ メタボ リズム; 本来の基質 とともに有機化合物 も酸素添加 され る)に よ り酸素添加 さ れる. 初発の酸素添加 によ りハ ロゲン置換脂肪族, ハロゲ ン置換芳香族, 多核芳香族化合物, 農薬等多様な物質の分 解性が決定される. これまでに数多 くの研究成果 と多数の 報告, 総説, 解説があ り参照 されたい1). 一方で, 近年これとは別の経路で分解 を行 う微生物の一 群が次第に解明されつつある2). これらはエネルギー獲得 のための呼吸系で水素, CO2, 有機酸を電子供与体 とし, 有 機塩素系化合物を電子受容体 とする嫌気呼吸により増殖が 可能な絶対嫌気性細菌に属す微生物であ り, その反応は脱 ハ ロゲン化呼吸 と呼ばれている3). これらの菌群 は, 好気性

Biological Degradation Of PCBs In Soil. A Kinetic Study

Abstract: In this paper a kinetic study is made of the biodegradability of Aroclor 1242 in sandy soil employing a mixed culture of acclimatized bacteria. The assays were done in stirred tank reactors, and the biodegradation process was monitored by High Resolution Gas Chromatography (HRGC) with Electron Capture Detector. These results are supported by other indirect measurements and indicators of the existence of microbial degradation process, as well as the parameters for the control of the process. The biodegradation occurred as a first order process and it proved most effective in respect of dechlorinated (100% removal), followed by trichlorinated (92Yo) and tetrachlorinated biphenyls (24Yo).