Biotransformation Patterns of 2,4,6-Trinitrotoluene by Aerobic Bacteria

2,4,6-Trinitrotoluene (TNT), a toxic nitroaromatic explosive, accumulates in the environment, making necessary the remediation of contaminated areas and unused materials. Although bioremediation has been utilized to detoxify TNT, the metabolic processes involved in the metabolism of TNT have proven to be complex. The three aerobic bacterial strains reported here (Pseudomonas aeruginosa, Bacillus sp., and Staphylococcus sp.) differ in their ability to biotransform TNT and in their growth characteristics in the presence of TNT. In addition, enzymatic activities have been identified that differ in the reduction of nitro groups, cofactor preferences, and the ability to eliminate-NO₂ from the ring. The Bacillus sp. has the most diverse bioremediation potential owing to its growth in the presence of TNT, high level of reductive ability, and capability of removing-NO₂ from the nitroaromatic ring. Received: 16 May 1997 / Accepted: 19 July 1997     

A 1,1,1-Trichloroethane-Degrading Anaerobic Mixed Microbial Culture Enhances Biotransformation of Mixtures of Chlorinated Ethenes and Ethanes

1,1,1-Trichloroethane (1,1,1-TCA) is a common groundwater pollutant as a result of improper disposal and accidental spills. It is often found as a cocontaminant with trichloroethene (TCE) and inhibits some TCE-degrading microorganisms. 1,1,1-TCA removal is therefore required for effective bioremediation of sites contaminated with mixed chlorinated organics. This study characterized MS, a 1,1,1-TCA-degrading, anaerobic, mixed microbial culture derived from a 1,1,1-TCA-contaminated site in the northeastern United States. MS reductively dechlorinated 1,1,1-TCA to 1,1-dichloroethane (1,1-DCA) and then to monochloroethane (CA) but not further. Cloning of bacterial 16S rRNA genes revealed among other organisms the presence of a Dehalobacter sp. and a Desulfovibrio sp., which are both phylogenetically related to known dehalorespiring strains. Monitoring of these populations with species-specific quantitative PCR during degradation of 1,1,1-TCA and 1,1-DCA showed that Dehalobacter proliferated during dechlorination. Dehalobacter growth was dechlorination dependent, whereas Desulfovibrio growth was dechlorination independent. Experiments were also performed to test whether MS could enhance TCE degradation in the presence of inhibiting levels of 1,1,1-TCA. Dechlorination of cis-dichloroethene (cDCE) and vinyl chloride (VC) in KB-1, a chloroethene-degrading culture used for bioaugmentation, was inhibited with 1,1,1-TCA present. When KB-1 and MS were coinoculated, degradation of cDCE and VC to ethene proceeded as soon as the 1,1,1-TCA was dechlorinated to 1,1-DCA by MS. This demonstrated the potential application of the MS and KB-1 cultures for cobioaugmentation of sites cocontaminated with 1,1,1-TCA and TCE.     

Aerobic Biotransformation of N-Nitrosodimethylamine and N-Nitrodimethylamine by Benzene-, Butane-, Methane-, Propane-, and Toluene-Fed Cultures

N-Nitrosodimethylamine (NDMA) is an emerging contaminant of concern. N-nitrodimethylamine (DMNA) is a structural analog to NDMA. NDMA and DMNA have been found in drinking water, groundwater, and other media and are of concern due their toxicity. The authors evaluated biotransformation of NDMA and DMNA by cultures enriched from contaminated groundwater growing on benzene, butane, methane, propane, or toluene. Maximum specific growth rates of enriched cultures on butane (μ_max = 1.1 h^?1) and propane (μ_max = 0.65 h^?1) were 1 to 2 orders of magnitude higher than those presented in the literature. Growth rates of mixed cultures grown on benzene (μ_max = 1.3 h^?1), methane (μ_max = 0.09 h^?1), and toluene (μ_max = 0.99 h^?1) in these studies were similar to those presented in the literature. NDMA biotransformation rates for methane oxidizers (υ_max = 1.4 ng min^?1 mg^?1) and toluene oxidizers (υ_max = 2.3 ng min^?1 mg^?1) were comparable to those presented in the literature, whereas the biotransformation rate for propane oxidizers (υ_max = 0.37 ng min^?1 mg^?1) was lower. NDMA biotransformation rates for benzene oxidizers (υ_max = 1.02 ng min^?1 mg^?1) and butane oxidizers (υ_max = 1.2 ng min^?1 mg^?1) were comparable to those reported for other primary substrates. These studies showed that DMNA biotransformation rates for benzene (υ_max = 0.79 ng min^?1 mg^?1), butane (υ_max = 1.0 ng min^?1 mg^?1), methane (υ_max = 2.1 ng min^?1 mg^?1), propane (υ_max = 1.46 ng min^?1 mg^?1), and toluene (υ_max = 0.52 ng min^?1 mg^?1) oxidizers were all comparable. These studies highlight potential bioremediation methods for NDMA and DMNA in contaminated groundwater.     

Biotransformation of antibiotics

Summary The absence of a lag period in the bioconversion of chloramphenicol by spores and the pronounced influence of the pH of the medium on this reaction strongly suggested that chloramphenicol acetyltransferase (CAT) is located at or near the surface of the spores of Streptomyces griseus. A two-hour exposure of spores to dilute solutions of -mercaptoethanol or surfactants resulted in significant decrease in activity even in the presence of glucose as an energy source. However, the inclusion of any of the reagents in the reaction mixture neither influenced the conversion activity nor the spore viability. These treatments did not reveal any cryptic activity for CAT in the spores. In addition, more drastic treatment of the spores with ethylenediaminetetraacetate (EDTA) or with concentrated salt solutions did not reduce the activity nor significantly affect the spore viability. Considering the modes of action of -mercaptoethanol and the surfactants, a combination of disulfide bridges and lipoprotein interactions may be responsible for the binding of CAT to the surface of the spore. Moreover, results of acid treatment of intact spores indicated that most of CAT activity, if not all, is located at the spore surface. Incorporation of ¹⁴C-acetate by cell-free extracts of Streptomyces griseus clearly showed that CAT selectively catalyzed the formation of chloramphenicol-3-acetate at an optimum pH of 6.5. The shape of the pH-activity curve in cell-free extracts is essentially identical to that of the enzyme in intact spores and is additional evidence that the enzyme is located at the spore surface.     

Biotransformation of Tetrahydrocannabinol

Cannabinoids are terpenophenolic compounds consisting of an aromatic polyketide and derived from the geranyl diphosphate C₁₀ terpenoid unit. They are the active constituents in Cannabis sativa and have been utilized in a number of cannabis-based medicines. Biotransformation of cannabinoids is an important field of xenobiochemistry and toxicology and the study of the metabolism of these compounds can lead to the discovery of new compounds, unknown metabolites with unique structures and new therapeutic entities. Different fungi, bacteria, plants and animal cells have been used for the regio- and stereoselective transformation of cannabinoids. All of the above mentioned organisms have distinct enzymes which catalyze the conversion of a specific cannabinoid at different positions and thus provide a variety of derivatives. All organisms are able to transform the alkyl side chain where as mammalians are unique in the formation of the carboxy derivatives. This review article assesses the current knowledge on the biotransformation of tetrahydrocannabinol and with particular focus on ?⁹-THC.     

Biotransformation of trichloroethylene in soil

Trichloroethylene was shown to degrade aerobically to carbon dioxide in an unsaturated soil column exposed to a mixture of natural gas in air (0.6%).     

Biotransformation of terpenes

The main application of terpenes as fragrances and flavors depends on the absolute configuration of the compounds because enantiomers present different organoleptic properties. Biotransformations allow the production of regio- and stereoselective compounds under mild conditions. These products may be labeled as "natural". Commercially useful chemical building-blocks and pharmaceutical stereo isomers can also be produced by bioconversion of terpenes. Enzymes and extracts from bacteria, cyanobacteria, yeasts, microalgae, fungi, plants, and animal cells have been used for the production and/or bioconversion of terpenes. In addition, whole cell catalysis has also been used. A variety of media and reactors have been assessed for these biotransformations and have produced encouraging results, as discussed in this review.     

Biotransformation of tetramethyl-limonene

Summary Microorganisms which efficiently oxidize limonene 1, do not attack 3,3,5,5-tetramethyllimonene 4. Gibberella cyanea which converts limonene 1 into 8-p-menthene-1,2-diol 2, transforms 4 into 8,9-epoxy-3,3,5,5-tetramethyl-1-menthenol-6 5 as major product. Although epoxidation is not completely stereoselective, the substituents at C-4 and C-6 are always trans to each other.     

手性药物合成中的生物转化

目前手性药物的发展非常迅速,本文介绍了利用微生物及其酶系作为生物催化剂,进行外消旋底物的拆分或前手性底物的不对称化,以合成手性药物的生物转化方法;并评述了生物转化在合成手性药物这一领域的应用现状及今后的发展趋势。     

Biotransformation of halogenated compounds

As a result of natural production and contamination of the environment by xenobiotic compounds, halogenated substances are widely distributed in the biosphere. Concern arises as a result of the toxic, carcinogenic, and potential teratogenic nature of these substances. The biotransformations of such halogenated substances are reviewed, with particular emphasis on the biocatalytic cleavage of the carbon-halogen bonds. The physiology, biochemistry, and genetics of the biological system involved in the dehalogenation reactions are discussed for three groups of organohalogens: (1) the haloacids, (2) the haloaromatics, and (3) the haloalkanes. Finally, the biotechnological applications of these microbial transformations are discussed. This includes prospects for their future application in biosynthetic processes for the synthesis of halogenated intermediates or novel compounds and also the use of such systems for the detoxification and degradation of environmental pollutants.     

原儿茶酸的生物转化

【背景】原儿茶酸(Protocatechuic acid,PCA)是一些植物的主要活性成分,可作为许多聚合物和药物的前体物质,目前PCA的主要来源是利用化学法从植物中提取,然而该法提取率低且对环境造成一定程度的破坏。【目的】克隆对羟基苯甲酸-3-羟化酶基因ρ-HBA-3H并进行异源表达,利用该酶催化实现原儿茶酸的生物转化。【方法】以红球菌R04基因组DNA为模板,PCR扩增得到对羟基苯甲酸-3-羟化酶基因ρ-HBA-3H,构建重组基因工程菌BL21(DE3)/pET21a(+)-ρ-HBA-3H,诱导表达对羟基苯甲酸-3-羟化酶,在底物对羟基苯甲酸(ρ-Hydroxybenzoicacid,ρ-HBA)存在下进行PCA的生物转化,并对生物转化的条件进行优化。【结果】对羟基苯甲酸-3-羟化酶基因在大肠杆菌中实现了高效表达。通过生物转化PCA产量可达1.156 g/L。优化实验表明Mg2+、Triton X-100对转化效率无影响,增加反应体系的溶氧量及添加适量的吐温-80能够促进转化反应的进行。细胞连续转化基础上适量补充葡萄糖可以有效增加工程菌的转化效率,减少PCA的消耗。【结论】通过生物酶催化法实现了PCA的高效率、绿色生产,为其他重要发酵产品的工业化生产提供理论研究基础。     

赤霉烯酮的微生物还原

用Rhodtorula sp.Saccharomyces sp.Arthorbacter sp.和Candida sp．四属20株菌对由Fusarium graminearum 产生的类雌激素——赤霉烯酮(Zearalenone)的还原转化进行了研究。实验结果证明,Rhodotorula sp和 Arthrobacter sp．的还原产物主要是α-赤霉烯醇(α-Zearalenol,经HPLC鉴定含量分别为96％和84％)。Saccharomyces sp．和Candidasp.的主要还原产物是β-赤霉烯醇(β-Zearalenol,经HPLC鉴定含量分别为91％和92％)。产物均经HPLC、13C—NMR和MS鉴定确证。     

Biotransformation of trichloroethylene in soil.

Trichloroethylene was shown to degrade aerobically to carbon dioxide in an unsaturated soil column exposed to a mixture of natural gas in air (0.6%).     

天然产物的生物转化

本文按反应类型综述了近五年来天然产物生物转化的研究进展,并对生物技术干预下的生物转化作了简要介绍.     

Biotransformation of rifampicin in pulmonary tuberculosis patients

Biotransformation of rifampicin in 39 tuberculosis patients treated with the drug was studied. The studies showed that biotransformation of rifampicin was most intensive during the first 3--6 hours after its use, which was confirmed by excretion of maximum amounts of rifampicin and its metabolites with the urine. 2--4 weeks after the beginning of the treatment with rifampicin excretion of its metabolism products decreased. When rifampicin was used simultaneously in a single dose with tubazid excretion of rifampicin transformation product and desacetylation of the antibiotic slowed down.     

有机硅橡胶固定化细胞进行的生物转化

有机硅橡胶固定化细胞进行的生物转化潘冰峰,戴学倩,冯青,李祖义（中国科学院上海有机化学研究所,２０００３２）关键词硅橡胶;白地霉;固定化细胞;生物转化近年来,有机化学领域的一个重要进展是用酶或微生物进行生物转化反应。其中研究和应用较多的是碳基还原,特...     

Biotransformation of cycloalkanones by microorganisms

Summary Washed-cell suspensions of cyclopentanol-grownPseudomonas sp. NCIB 9872 were shown to preferentially biotransform norbornanone to an equivalent lactone of potential use in the synthesis of prostanoid analogues. Conditions to optimise the yield of product, including incubation at pH 7.1–7.35 and at substrate concentrations <15 mM, have been established.     

Biotransformation of N-acetylphenothiazine by fungi

Cultures of the fungi Aspergillus niger, Cunninghamella verticillata, and Penicillium simplicissimum, grown in a sucrose/peptone medium, transformed N-acetylphenothiazine to N-acetylphenothiazine sulfoxide (from 13% to 28% of the total) and phenothiazine sulfoxide (from 5% to 27%). Phenothiazin-3-one (4%) and phenothiazine N-glucoside (4%) were also produced by C. verticillata. The probable intermediate, phenothiazine, was detected only in cultures of P. simplicissimum (6%). Received: 15 January 1999 / Received revision: 7 May 1999 / Accepted: 21 May 1999     

Significant Biogenesis of Chlorinated Aromatics by Fungi in Natural Environments

Common wood- and forest litter-degrading fungi produce chlorinated anisyl metabolites. These compounds, which are structurally related to xenobiotic chloroaromatics, occur at high concentrations of approximately 75 mg of chlorinated anisyl metabolites kg of wood^-1 or litter^-1 in the environment. The widespread ability among common fungi to produce large amounts of chlorinated aromatic compounds in the environment makes us conclude that these kinds of compounds can no longer be considered to originate mainly from anthropogenic sources.