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Showing papers on "Microbial biodegradation published in 2010"


Journal ArticleDOI
TL;DR: Given these metabolites are water-soluble and non-toxic, the findings suggest a potential bioremediation role of Bacillus fusiformis (BFN) in the removal of naphthalene from wastewaters.

161 citations


Journal ArticleDOI
TL;DR: Overall, studies demonstrated that aquatic plants contribute directly and indirectly to the aqueous depletion of emerging organic pollutants in wetland systems through both active and passive processes.

133 citations


Book ChapterDOI
TL;DR: The review describes the microbial degradation of both naturally occurring and chemically synthesized NAs, and proposed pathways for aerobic NA biodegradation, factors affecting NABiodegradation rates, and possible bioremediation strategies are discussed.
Abstract: Naphthenic acids (NAs) are an important group of trace organic pollutants predominantly comprising saturated aliphatic and alicyclic carboxylic acids. NAs are ubiquitous; occurring naturally in hydrocarbon deposits (petroleum, oil sands, bitumen, and crude oils) and also have widespread industrial uses. Consequently, NAs can enter the environment from both natural and anthropogenic processes. NAs are highly toxic, recalcitrant compounds that persist in the environment for many years, and it is important to develop efficient bioremediation strategies to decrease both their abundance and toxicity in the environment. However, the diversity of microbial communities involved in NA-degradation, and the mechanisms by which NAs are biodegraded, are poorly understood. This lack of knowledge is mainly due to the difficulties in identifying and purifying individual carboxylic acid compounds from complex NA mixtures found in the environment, for microbial biodegradation studies. This paper will present an overview of NAs, their origin and fate in the environment, and their toxicity to the biota. The review describes the microbial degradation of both naturally occurring and chemically synthesized NAs. Proposed pathways for aerobic NA biodegradation, factors affecting NA biodegradation rates, and possible bioremediation strategies are also discussed.

131 citations


Journal ArticleDOI
TL;DR: A consortium of white-rot fungi isolated from wood pieces was used for studying their potential of bioremediation of PAHs and the relative contributions of biosorption and biodegradation under different nutrient conditions.

118 citations


Journal ArticleDOI
TL;DR: In this paper, the biodegradability of polycyclic aromatic hydrocarbons such as naphthalene, fluorene, anthracene and phenanthrene by a halotolerant bacterial consortium isolated from marine environment was investigated.
Abstract: The biodegradability of polycyclic aromatic hydrocarbons such as naphthalene, fluorene, anthracene and phenanthrene by a halotolerant bacterial consortium isolated from marine environment was investigated. The polycyclic aromatic hydrocarbons degrading bacterial consortium was enriched from mixture saline water samples collected from Chennai (Port of Chennai, salt pan), India. The consortium potently degraded polycyclic aromatic hydrocarbons (> 95%) at 30g/L of sodium chloride concentration in 4 days. The consortium was able to degrade 39 to 45% of different polycyclic hydrocarbons at 60 g/L NaCl concentration. Due to increase in salinity, the percent degradation decreased. To enhance polycyclic aromatic hydrocarbons degradation, yeast extract was added as an additional substrate at 60g/L NaCl concentration. After the addition of yeast extract, the consortium degraded > 74 % of polycyclic aromatic hydrocarbons at 60 g/L NaCl concentration in 4 days. The consortium was also able to degrade PAHs at different concentrations (5, 10, 20, 50 and 100 ppm) with 30 g/L of NaCl concentration. The polycyclic aromatic hydrocarbons degrading halotolerant bacterial consortium consists of three bacterial strains, namely Ochrobactrum sp., Enterobacter cloacae and Stenotrophomonas maltophilia.

102 citations



Journal ArticleDOI
TL;DR: This work generated a self-consistent set of biotransformation data for amide-containing compounds and developed a metabolic logic that describes the preferred biotranformation pathways of these compounds as a function of structural and electronic descriptors.
Abstract: Partial microbial degradation of xenobiotic compounds in wastewater treatment plants (WWTPs) results in the formation of transformation products, which have been shown to be released and detectable in surface waters. Rule-based systems to predict the structures of microbial transformation products often fail to discriminate between alternate transformation pathways because structural influences on enzyme-catalyzed reactions in complex environmental systems are not well understood. The amide functional group is one such common substructure of xenobiotic compounds that may be transformed through alternate transformation pathways. The objective of this work was to generate a self-consistent set of biotransformation data for amide-containing compounds and to develop a metabolic logic that describes the preferred biotransformation pathways of these compounds as a function of structural and electronic descriptors. We generated transformation products of 30 amide-containing compounds in sludge-seeded bioreactors...

90 citations


Journal ArticleDOI
TL;DR: It is suggested the toxic nature of PAHs retarded mineralisation at increased contaminant concentrations, whereas the presence of naphthalene significantly enhanced rates of mineralisation in multiple-contaminant systems containing (14)C-phenanthrene and (14).

89 citations


Journal ArticleDOI
TL;DR: This study investigated the biodegradability of three ILs and determined that IL-biodegradation products were less toxic than the initial compound to a standard aquatic test organism, Daphnia magna, suggesting that biodegradation in an aquatic environment would decrease toxicity hazards associated with theInitial compound.

89 citations


Journal ArticleDOI
TL;DR: Investigation of bioremediation experiments on harbor sediments contaminated by aliphatic and polycyclic aromatic hydrocarbons suggests that C availability in the sediments, influencing prokaryotic metabolism, may have cascade effects on biodegradation rates of hydrocarbon.

84 citations


Journal ArticleDOI
TL;DR: In this article, the ability of a microbial consortium to degrade equivalent carbon number (EC) based hydrocarbon fractions in kerosene has attracted little attention; however, the biodegradation of petroleum products using total petroleum hydrocarbons (TPH) have been carried out; therefore, the microbial community was predominantly identified as Betaproteobacteria of the genera Achromobacter, Alcaligenes, and Cupriavidus.

Journal Article
TL;DR: In this article, the authors investigated whether agricultural fertilizers (N, P, K) enhance the microbial degradation of petroleum hydrocarbons in soil and found that the applied fertilizer increased the degradation of the hydro-carbons compared with the control.
Abstract: pollution is a worldwide threat to the environment and the remediation of oil-contaminated soils, sediments and water is a major challenge for environmental research. Bioremediation is a useful method for soil remediation, if pollutant concentrations are moderate and non-biological techniques are not economical. The bioremediation consists strategy of actively aerating the soils and adding fertilizer in order to promote oil biodegradation by indigenous microorganisms. The objective of this study was to investigate whether agricultural fertilizers (N, P, K) enhance the microbial degradation of petroleum hydrocarbons in soil. Artificially polluted soil with %1density of crude oil was used and then fertilizers were applied in 3 levels of 0, 1 and 2 ton/ha in 3 replicates. The soils were kept in 30 oC and 60 percent of field capacity condition for 5 to 10 weeks. To provide the necessary aeration, the soils were tilled twice a week by shovel. Soil sample were analyzed for hydrocarbon-degrading heterophic bacteria count and some soil chemical properties. Residual oil was measured by oil soxhlet extraction method, and gas chromatography. The results showed that the hydrocarbon-degrading and heterotrophic bacteria count in all the treatments increased with time and heterotrophic bacteria population increased from 6×10 3 cfu/g soil to 1.4×10 8 cfu/g soil. Also, soil C/N ratio decreased from 6 to 3. The results indicated that the applied fertilizer increased the degradation of the hydrocarbons compared with the control. Gas chromatography results showed that normal paraffin and isopernoid (Phitane and Pristane) decreased in the range of 45 to 60 percent in all treatments. Furthermore, the results showed that the application of fertilizers at 2 ton/ha rate in oil-contaminated soil lead to greater rates of biodegradation after 5 weeks indicating the feasibility of bioremediation.

Journal ArticleDOI
TL;DR: The possibility to substitute methane with biogas from renewable sources facilitates the development of a methane‐based PHB production process that yields a high‐quality biopolymer at competitive costs.
Abstract: Methanotrophic bacteria possess a unique set of enzymes enabling them to oxidize, degrade and transform organic molecules and synthesize new compounds Therefore, they have great potential in environmental biotechnology The application of these unique properties was demonstrated in three case studies: (i) Methane escaping from leaky gas pipes may lead to massive mortality of trees in urban areas Lack of oxygen within the soil surrounding tree roots caused by methanotrophic activity was identified as one of the reasons for this phenomenon The similarity between metabolic reactions performed by the key enzymes of methanotrophs (methane monooxygenase) and ammonium oxidizers (ammonium monooxygenase) might offer a solution to this problem by applying commercially available nitrification and urease inhibitors (ii) Methanotrophs are able to co-metabolically degrade contaminants such as low-molecular-weight-chlorinated hydrocarbons in soil and water in the presence of methane Batch and continuous trichloroethylene degradation experiments in laboratory-scale reactors using Methylocystis sp GB 14 were performed, partly with cells entrapped in a polymer matrix (iii) Using a short, two-stage pilot-scale process, the intracellular polymer accumulation of poly-β-hydroxybutyrate (PHB) in methanotrophs reached a maximum of 52% Interestingly, an ultra-high-molecular-weight PHB of 31 MDa was accumulated under potassium deficiency Under strictly controlled conditions (temperature, pH and methane supply) this process can be nonsterile because of the establishment of a stable microbial community (dominant species Methylocystis sp GB 25 ≥86% by biomass) The possibility to substitute methane with biogas from renewable sources facilitates the development of a methane-based PHB production process that yields a high-quality biopolymer at competitive costs

Journal ArticleDOI
Tingting Li1, Shuhai Guo1, Bo Wu1, Fengmei Li1, Zhi-xin Niu1 
TL;DR: The degradation rate of alkane was 1.6 times higher in the soil exposed to electric current than that treated with bacteria for 100 days, indicating a proper direct current could stimulate the microbial activities and accelerate the biodegradation of petroleum.
Abstract: Electro-bioremediation is an innovative method to remedy organic-polluted soil. However, the principle of electrokinetic technology enhancing the function of microbes, especially the relationship of electric intensity and biodegradation efficiency, is poorly investigated. Petroleum was employed as a target organic pollutant at a level of 50 g/kg (mass of petroleum/mass of dry soil). A direct current power supply was used for tests with a constant direct current electric voltage (1.0 V/cm). The petroleum concentrations were measured at 3275-3285 nm after extraction using hexane, the group composition of crude oil was analyzed by column chromatography. The water content of soil was kept 25% ( m / m ). The results indicated the degradation process was divided into two periods: from day 1 to day 40, from day 41 to day 100. The treatment of soil with an appropriate electric field led the bacteria to have a persistent effect in the whole period of 100 days. The highest biodegradation efficiency of 45.5% was obtained after treatment with electric current and bacteria. The electric-bioremediation had a positive effect on alkane degradation. The degradation rate of alkane was 1.6 times higher in the soil exposed to electric current than that treated with bacteria for 100 days. A proper direct current could stimulate the microbial activities and accelerate the biodegradation of petroleum. There was a positive correlation between the electric intensities and the petroleum bioremediation efficiencies with a coefficient of 0.9599.

Journal ArticleDOI
TL;DR: EH831 was able to degrade many recalcitrant hydrocarbons at higher degradation rates compared with previous well-known degraders, and primarily suggested the aerobic biodegradation pathway, which may provide valuable information for researchers and engineers working in the field of environmental engineering.
Abstract: Hexane, a representative VOC, is used as a solvent for extraction and as an ingredient in gasoline. The degradation of hexane by bacteria is relatively slow due to its low solubility. Moreover, the biodegradation pathway of hexane under aerobic conditions remains to be investigated; therefore, a study relating to aerobic biodegradation mechanisms is required. Consequently, in this study, an effective hexane degrader was isolated and the biodegradation pathway examined for the first time. In addition, the degradation characteristics of a variety of recalcitrant hydrocarbons were qualitatively and quantitatively investigated using the isolate. A hexane-degrading bacterium was isolated from an enrichment culture using petroleum-contaminated soil as an inoculum with hexane as the sole carbon and energy source. The bacterium was also identified using the partial 16S rRNA gene sequence. To test the hexane-degrading capacity of the isolate, 10 ml of an EH831 cell suspension was inoculated into a 600-ml serum bottle with hexane (7.6–75.8 μmol) injected as the sole carbon source. The rates of hexane degradation were determined by analyzing the concentrations of hexane using headspace gas chromatography. In addition, the hexane biodegradation pathway under aerobic conditions was investigated by identifying the metabolites using gas chromatography–mass spectrometry with solid-phase microextraction. 14C-hexane was used to check if EH831 could mineralize hexane in the same experimental system. The degradabilities of other hydrocarbons were examined using EH831 with methanol, ethanol, acetone, cyclohexane, methyl tert-butyl ether (MTBE), dichloromethane (DCM), trichloroethylene, tetrachloroethylene, benzene, toluene, ethylbenzene, xylene (BTEX), pyrene, diesel, lubricant oil, and crude oil as sole carbon sources. A bacterium, EH831, was isolated from the enriched hexane-degrading consortium, which was able to degrade hexane and various hydrocarbons, including alcohols, chlorinated hydrocarbons, cyclic alkanes, ethers, ketones, monoaromatic and polyaromatic hydrocarbons, and petroleum hydrocarbons. The maximum hexane degradation rate (V max) of EH831 was 290 μmol g dry cell weight−1 h−1, and the saturation constant (K s) was 15 mM. Using 14C-hexane, EH831 was confirmed to mineralize approximately 49% of the hexane into CO2 and, converted approximately, 46% into biomass; the rest (1.7%) remained as extracellular metabolites in the liquid phase. The degradation pathway was assessed through the qualitative analysis of the hexane intermediates due to EH831, which were 2-hexanol, 2-hexanone, 5-hexen-2-one and 2,5-hexanedione, in that order, followed by 4-methyl-2-pentanone, 3-methly-1-butanol, 3-methyl-1-butanone and butanal, and finally, CO2. EH831 could degrade methanol, ethanol, acetone, cyclohexane, MTBE, DCM, BTEX, pyrene, diesel, and lubricant oil. EH831 was able to degrade many recalcitrant hydrocarbons at higher degradation rates compared with previous well-known degraders. Furthermore, this study primarily suggested the aerobic biodegradation pathway, which may provide valuable information for researchers and engineers working in the field of environmental engineering. Rhodococcus sp. EH831 is a promising bioresource for removing hexane and other recalcitrant hydrocarbons from a variety of environments. Moreover, the aerobic biodegradation pathway is reported for the first time in this study, which offers valuable information for understanding the microbial degradation of hexane. The utility of the strain isolated in this study needs to be proved by its application to biological process systems, such as biofilters and bioreactors, etc., for the degradation of hexane and many other recalcitrant hydrocarbons. Detailed investigations will also be needed to clarify the enzymatic characteristics relating the degradation of both recalcitrant hydrocarbons and hexane.

01 Jan 2010
TL;DR: Colorimetric methodology applied to oil biodegradation promotes a better handling of different oil microbial biodegrading profiles, and provides resources on the development of new techniques in effluent treatments, not only during petrol derived oils, but also on other contaminated organic polymeric compounds.
Abstract: The increasing industrial development promotes serious environmental damage due to pollution of the environment. Regarding the petrochemical industry, contamination by oil and its derivatives causes the degradation of terrestrial and aquatic ecosystems. Thus, control and treatment strategies to combat the hazardous effects of oil pollution are needed. However, conventional physical*chemical treatments have high costs and can generate residues that are toxic to the biota. Allying high efficiency and low cost, bioremediation processes represent an extremely important way of recovering contaminated areas among several other cleaning*up techniques. These strategies involve microorganisms and their metabolism in biodegrading organic compounds. Also, the use of nutrients, aeration, pH and temperature adjustments or the addition of substances could make the biodegradation process easier. In order to accomplish this, screening and evaluation methods adapted to a potentially biodegrading microbiota in different types of contaminants have been established. Viable methods in biodegradation data generation during biotechnological process application are fundamental in the elaboration of original references about the biodegradability of certain substances. There are many techniques capable of precisely evaluating biodegradation processes, including colorimetric methods. The isolation, characterization and profile of specific bacteria in petrol derived oil biodegradation capacity studies are important when deciding the correct bioremediation strategy. Different microorganism species have different biodegradation capabilities. Due to this fact, the elaboration of different types of oil biodegradation profiles by different bacteria is an important task for selecting microorganisms in bioremediation processes. In order to accomplish this, screening and evaluation methods adapted to potentially biodegrading bacteria have been established. One of these methods adapted to biodegradation evaluation is colorimetry, which is a technique used to evaluate the biodegradation of some substances. DCPIP based colorimetric technique provides enough data on hydrocarbons used as metabolic substrates by microorganisms. The concentration detection is possible due to the absorbance determination in a specified light specter. The 2,6*dichlorophenol indophenol (DCPIP, redox potential +0.217 V) indicator is widely used in colorimetric processes. Its property is the color change from blue to transparent when subjected to chemical reduction. The indicator, when oxidized is blue and when reduced is transparent. The color change occurs due to a structural change in the molecule, in which the double bond between nitrogen and carbon passes to a simple bond. This insaturation changes the entire molecule, resulting in a macroscopic change in the overall color of the biodegraded substance. The DCPIP indicator is applied in a series of electron transfer reactions, including biodegradable substances. Colorimetric methodology applied to oil biodegradation promotes a better handling of different oil microbial biodegrading profiles. Moreover, such rapid and simple colorimetric methodology provides resources on the development of new techniques in effluent treatments, not only during petrol derived oils, but also on other contaminated organic polymeric compounds.

Journal ArticleDOI
TL;DR: Most of the compounds detected in control samples were diminished from the bacterial degraded samples and compounds 2, 2′-bifuran and indole with molecular weight 134 and 117 were produced as new metabolites during the bacterial degradation of color containing compounds from DWW.
Abstract: This study deals the biodegradation of the major color containing compounds extracted from distillery wastewater (DWW) by an aerobic bacterial consortium comprising Bacillus licheniformis (DQ79010), Bacillus sp. (DQ779011) and Alcaligenes sp. (DQ779012) and characterization of metabolic products. The degradation of color containing compounds by bacteria was studied by using the different carbon and nitrogen sources at different environmental conditions. Results revealed that the bacterial consortium was efficient for 70% color removal in presence of glucose (1.0%) and peptone (0.1%) at pH 7.0 and temperature 37°C. The HPLC analysis of control and bacterial degraded samples has shown the reduction in peak area as well as shifting of peaks compared to control indicating the bacterial degradation as well as transformation of color containing compounds from DWW. The comparative LC–MS–MS and other spectrophotometric analysis has shown the presence of dihydroxyconiferyl alcohol, 2, 2′-bifuran-5-carboxylic acid, 2-nitroacetophenone, p-chloroanisol, 2, 3-dimethyl-pyrazine, 2-methylhexane, methylbenzene, 2, 3-dihydro-5-methylfuran, 3-pyrroline, and acetic acid in control samples that were biodegraded and biotransformed into 2-nitroacetophenone, p-chloroanisol, 2, 2′-bifuran, indole, 2-methylhexane, and 2, 3-dihydro-5-methylfuran by bacterial consortium. In this study, it was observed that most of the compounds detected in control samples were diminished from the bacterial degraded samples and compounds 2, 2′-bifuran and indole with molecular weight 134 and 117 were produced as new metabolites during the bacterial degradation of color containing compounds from DWW.

Journal ArticleDOI
TL;DR: Cellular and molecular modifications induced by mixture of saturated, monoaromatic and polyaromatic hydrocarbons to Gram-positive and Gram-negative bacteria differ from one strain to another and even for the same bacterial strain, according to the nature of hydrophobic substrate

Journal ArticleDOI
Fusako Kawai1
TL;DR: In this review, the molecular biological and biochemical aspects of the microbial degradation of xenobiotic polymers are summarized, and possible applications of potent microorganisms, enzymes, and genes in environmental biotechnology are suggested.
Abstract: Research on microbial degradation of xenobiotic polymers has been underway for more than 40 years. It has exploited a new field not only in applied microbiology but also in environmental microbiology, and has greatly contributed to polymer science by initiating the design of biodegradable polymers. Owing to the development of analytical tools and technology, molecular biological and biochemical advances have made it possible to prospect for degrading microorganisms in the environment and to determine the mechanisms involved in biodegradation when xenobiotic polymers are introduced into the environment and are exposed to microbial attack. In this review, the molecular biological and biochemical aspects of the microbial degradation of xenobiotic polymers are summarized, and possible applications of potent microorganisms, enzymes, and genes in environmental biotechnology are suggested.

Journal ArticleDOI
TL;DR: Results from MTBE biodegradation experiment show that the isolated bacteria were affected by propane, which indicates that propane may influence the metabolic pathway of MTBE by these bacteria.

Journal ArticleDOI
TL;DR: The key factors underlying dechlorination of CCl(4), the practical aspects and specific requirements for microorganism-associated degradation of C Cl(4) at contaminated sites and perspectives for future developments are discussed.

Journal ArticleDOI
TL;DR: The growth capabilities of a diesel-degrading consortium, along with organisms isolated from a contaminated site, were investigated and indicated that the degradation of the fuel's constituents may be shared among the diverse microbial community.
Abstract: Diesel fuel is a common environmental pollutant comprised of a large number of both aromatic and aliphatic hydrocarbons. The microbial degradation of individual hydrocarbons has been well characterized, however, the community dynamics within a system degrading a complex pollutant such as diesel fuel are still poorly understood. The growth capabilities of a diesel-degrading consortium, along with organisms isolated from a contaminated site, were investigated using molecular profiling, isolation, and physiological methods using 10 of the fuel's most abundant constituents as sole carbon sources. The results indicated that the degradation of the fuel's constituents may be shared among the diverse microbial community. Some organisms were capable of growth on the majority of the hydrocarbons tested, whereas others seemed specialized to only a few of the substrates.

Journal ArticleDOI
TL;DR: Stable-isotope probing (SIP)-terminal restriction fragment length polymorphism (TRFLP) detected peaks in the [15N]TNT cultures (60, 163, and 168 bp) that were related to Lysobacter taiwanensis.
Abstract: It has been estimated that there are over 1 million cubic yards of material contaminated with 2,4,6-trinitrotoluene (TNT) in the United States at concentrations as high as 600,000 to 700,00 mg/kg of material (9). Marine and estuarine sediments have also been impacted through the manufacturing, use, and/or disposal of TNT. Microbial biodegradation of these pollutants in situ is preferable due to the large volume of contaminated soils/sediments. However, it is unclear whether in situ bacteria can utilize TNT as a nitrogen or carbon source. Under aerobic conditions, TNT appears to be largely unavailable to bacteria but can be used by a variety of fungi as a carbon and nitrogen source (7). Under anaerobic conditions, only a few bacterial strains (Clostridium and Desulfovibrio strains and Pseudomonas sp. strain JLR11) have been reported to utilize TNT as a sole nitrogen source (6, 7). It is widely believed that nitroaromatic compounds cannot serve as growth substrates under anaerobic conditions in situ (11), and coamendment strategies are suggested for stimulating TNT transformation to 2,4,6-triaminotoluene (TAT) (1, 7, 18). Given these difficulties, there is no direct evidence that TNT can be biodegraded in situ and there is little proof that anaerobic bacteria can utilize TNT as a sole carbon or nitrogen source in organic-rich sediments. This study tested whether bacteria in Norfolk Harbor sediment are able to incorporate nitrogen (N) or carbon (C) from TNT into biomass under sulfidogenic conditions using stable-isotope probing (SIP). The findings indicate that bacteria assimilate 15N and 13C from TNT into their genomes during anaerobic incubations (2 to 35 days). Interestingly, one small-subunit (SSU) gene, related to Lysobacter taiwanensis, was observed in both the 15N and the 13C incubations.

Journal ArticleDOI
TL;DR: This minireview considers the ability of AOB to carry out cometabolism of halogenated compounds and the consequent inhibition of nitrification in ammonia-oxidizing bacteria in Nitrosomonas europaea.
Abstract: The process of nitrification has the potential for the in situ bioremediation of halogenated compounds provided a number of challenges can be overcome. In nitrification, the microbial process where ammonia is oxidized to nitrate, ammonia-oxidizing bacteria (AOB) are key players and are capable of carrying out the biodegradation of recalcitrant halogenated compounds. Through industrial uses, halogenated compounds often find their way into wastewater, contaminating the environment and bodies of water that supply drinking water. In the reclamation of wastewater, halogenated compounds can be degraded by AOB but can also be detrimental to the process of nitrification. This minireview considers the ability of AOB to carry out cometabolism of halogenated compounds and the consequent inhibition of nitrification. Possible cometabolism monitoring methods that were derived from current information about AOB genomes are also discussed. AOB expression microarrays have detected mRNA of genes that are expressed at higher levels during stress and are deemed “sentinel” genes. Promoters of selected “sentinel” genes have been cloned and used to drive the expression of gene-reporter constructs. The latter are being tested as early warning biosensors of cometabolism-induced damage in Nitrosomonas europaea with promising results. These and other biosensors may help to preserve the tenuous balance that exists when nitrification occurs in waste streams containing alternative AOB substrates such as halogenated hydrocarbons.

Journal ArticleDOI
TL;DR: Synthetic surfactants and biosurfactants will be discussed as a means to mobilize and solubilize PAHs, potentially increasing bioavailability and subsequent microbial degradation.
Abstract: The activities of man produce significant levels of toxic polycyclic aromatic hydrocarbon compounds (PAHs), which have been identified as excellent candidates for biodegradative removal from contaminated sites. PAHs strongly sorb to soil particles and can also partition into a nonaqueous phase, often limiting bioavailability. In this context, synthetic surfactants and biosurfactants will be discussed as a means to mobilize and solubilize PAHs, potentially increasing bioavailability and subsequent microbial degradation. The fundamentals of bioremediation will be discussed as an important tool that can be used to reduce, remove, or attenuate pollutants at PAH-contaminated sites.

Journal ArticleDOI
TL;DR: For samples collected over 45 d, ND24 values did not necessarily correlate with ergosterol or laccase amounts but in most cases, they were over 30% degradation, indicating that T. versicolor may be suitable for bioremediation of sewage sludge in the studied period.

Journal ArticleDOI
TL;DR: The degradation of 4-monobrominated diphenyl ether (4-BDE) in aerobic sludge, as a model for PBDE biodegradation, was examined in this article.
Abstract: Polybrominated diphenyl ethers (PBDEs) were applied as flame retardant additives in polymers for many plastic and electronic products. Due to their ubiquitous distribution in the environment, potential toxicity to human and tendency for bioaccumulation, PBDEs have raised public safety concern. In this study we examined the degradation of 4-monobrominated diphenyl ether (4-BDE) in aerobic sludge, as a model for PBDE biodegradation. Degradation of 4-BDE was observed in aerobic sludge. Co-metabolism with toluene or diphenyl ether facilitated 4-BDE biodegradation in terms of kinetics and efficiency. Diphenyl ether seems to perform slightly better as an auxiliary carbon source than toluene in facilitating 4-BDE degradation. During the experiment we identified diphenyl ether by gas chromatography/mass spectrometry(GC/MS), which indicates that an anaerobic debromination has occurred. Bacterial community composition was monitored with denaturing gradient gel electrophoresis. The fragments enriched in 4-BDE-degrading aerobic sludge samples belong to presumably a novel anaerobic Clostridiales species distantly related to all known debrominating microbes. This suggests that 4-BDE biodegradation can occur in anaerobic micro-niche in an apparently aerobic environment, by a previously unknown bacterial species. These findings can provide better understandings of biodegradation of brominated diphenyl ethers and can facilitate the prediction of the fate of PBDEs in the environment.

Journal ArticleDOI
TL;DR: The ability of facultative anaerobic iron-reducing bacteria to degrade estrogens can be used for the anaerobia removal of trace organics from reject water in municipal wastewater treatment plant.

Journal ArticleDOI
TL;DR: The approach demonstrates the possibility to use the engineered psychrophilic bacterium for the bioremediation of chemically contaminated marine environments and/or cold effluents.
Abstract: Microbial degradation of aromatic hydrocarbons has been studied with the aim of developing applications for the removal of toxic compounds. Efforts have been directed toward the genetic manipulation of mesophilic bacteria to improve their ability to degrade pollutants, even though many pollution problems occur in sea waters and in effluents of industrial processes which are characterized by low temperatures. From these considerations the idea of engineering a psychrophilic microorganism for the oxidation of aromatic compounds was developed.In a previous paper it was demonstrated that the recombinant Antarctic Pseudoalteromonas haloplanktis TAC125 (PhTAC/tou) expressing a toluene-o-xylene monooxygenase (ToMO) is able to convert several aromatic compounds into corresponding catechols. In our work we improved the metabolic capability of PhTAC/tou cells by combining action of recombinant ToMO enzyme with that of the endogenous P. haloplanktis TAC125 laccase-like protein. This strategy allowed conferring new and specific degradative capabilities to a bacterium isolated from an unpolluted environment; indeed engineered PhTAC/tou cells are able to grow on aromatic compounds as sole carbon and energy sources. Our approach demonstrates the possibility to use the engineered psychrophilic bacterium for the bioremediation of chemically contaminated marine environments and/or cold effluents.

Journal ArticleDOI
TL;DR: The efficient degradation, as evident by RP-HPLC, by this isolate holds a promising potential for planning of bioremediation strategies of contaminated sites.
Abstract: Polycyclic aromatic hydrocarbons (PAHs) are common ubiquitous pollutants existing in nature with high recalcitrance and toxicity. In this study a bacterium capable of aerobic degradation of high molecular weight PAHs (with special reference to pyrene) was isolated by selective enrichment culture technique from oil refinery effluent sludge. The isolate was characterized as Achromobacter xylooxidans by 16S rRNA gene sequence analysis technique. For the first time it is hereby reported a bacterium capable of effectively degrading pyrene (up to 80%), as evident by reverse phase high performance liquid chromatographic analysis (RP-HPLC). After incubation of Achromobacter xylooxidans in minimal salt medium (MSM) containing pyrene, at concentration of 200 mg/L, as sole source of carbon and energy, there was decrease in pyrene concentration concomitant with increase in bacterial cell protein concentration. RP-HPLC analysis revealed that pyrene was degraded into three metabolites viz. I, II and III. The RP-HPLC eluent fraction were collected from 2.5 to 32.0 min by repeated injection of degraded sample, concentrated and analyzed on gas chromatography mass spectroscopy (GC-MS) for metabolite identification. The fraction shows 1-hydroxypyrene, 1-hydroxy-6-methoxypyrene and 1,6dimethoxypyrene as metabolic product of pyrene degradation, on the basis of their m/z values. On contrary to the reported PAH degradation with reference to pyrene by different isolates till date; the efficient degradation, as evident by RP-HPLC, by this isolate holds a promising potential for planning of bioremediation strategies of contaminated sites.