Cytochrome P-450-dependent catabolism of triethanolamine in Rhodotorula mucilaginosa

The yeast Rhodotorula mucilaginosa was able to grow in media containing triethanolamine or diethanolamine as the sole nitrogen source. During growth in the presence of triethanolamine, extracts of yeast cells contained increased levels of cytochrome P-450 dependent monooxygenase which catalyzed the oxidative N-dealkylation of aminoalcohols. Formation of diethanolamine, ethanolamine and glyoxylate from triethanolamine was demonstrated, and the identity of the products was verified by thin layer chromatography. These observations suggested the following scheme of triethanolamine catabolism: triethanolamine → diethanolamine + glycolaldehyde, diethanolamine → ethanolamine + glycolaldehyde, ethanolamine → NH3 + glycolaldehyde → glycolate → glyoxylate → glycerate pathway. © 1991 Kluwer Academic Publishers

Removal of the endocrine disrupter butyl benzyl phthalate from the environment

Butyl benzyl phthalate (BBP), an aryl alkyl ester of 1,2-benzene dicarboxylic acid, is extensively used in vinyl tiles and as a plasticizer in PVC in many commonly used products. BBP, which readily leaches from these products, is one of the most important environmental contaminants, and the increased awareness of its adverse effects on human health has led to a dramatic increase in research aimed at removing BBP from the environment via bioremediation. This review highlights recent progress in the degradation of BBP by pure and mixed bacterial cultures, fungi, and in sludge, sediment, and wastewater. Sonochemical degradation, a unique abiotic remediation technique, and photocatalytic degradation are also discussed. The degradation pathways for BBP are described, and future research directions are considered

Degradation of haloaromatic compounds

An ever increasing number of halogenated organic compounds has been produced by industry in the last few decades. These compounds are employed as biocides, for synthetic polymers, as solvents, and as synthetic intermediates. Production figures are often incomplete, and total production has frequently to be extrapolated from estimates for individual countries. Compounds of this type as a rule are highly persistent against biodegradation and belong, as "recalcitrant" chemicals, to the class of so-called xenobiotics. This term is used to characterise chemical substances which have no or limited structural analogy to natural compounds for which degradation pathways have evolved over billions of years. Xenobiotics frequently have some common features. e.g. high octanol/water partitioning coefficients and low water solubility which makes for a high accumulation ratio in the biosphere (bioaccumulation potential). Recalcitrant compounds therefore are found accumulated in mammals, especially in fat tissue, animal milk supplies and also in human milk. Highly sophisticated analytical techniques have been developed for the detection of organochlorines at the trace and ultratrace level

Organization and control of genes encoding catabolic enzymes in Rhizobiaceae

Rhizobiaceae, a diverse bacterial group comprising rhizobia and agrobacteria, symbiotic partnership with plants form nitrogen-fixing nodules on plant roots or are plant pathogens. Phenolic compounds produced by plants serve as inducers of rhizobial nodulation genes and agrobacterial virulence genes reflect their capacity to utilize numerous aromatics, including phenolics, as a source of carbon and energy. In many microbes the aerobic degradation of numerous aromatic compounds to tricarboxylic acid cycle intermediates is achieved by the [beta]-ketoadipate pathway. Our initial studies focused on the organization and regulation of the ketoadipate pathway in Agrobacterium tumefaciens. We have cloned, identified and characterized a novel regulatory gene that modulates expression of an adjacent pca (protocatechuate) structural gene, pcaD. Regulation of pcaD is mediated by the regulatory gene, termed pcaQ, in concert with the intermediate [beta]-carboxy-cis,cis-muconate. [beta]-carboxy-cis,cismuconate is an unstable chemical, not marketed commercially, and it is unlikely to permeate Escherichia coli cells if supplied in media. Because of these factors, characterization of pcaQ in E. coli required an in vivo delivery system for [beta]-carboxycis,cis-muconate. This was accomplished by designing an E. coli strain that expressed an Acinetobacter calcoaceticus pcaA gene for conversion of protocatechuate to [beta]-carboxy-cis,cis-muconate

Properties of an inducible uptake system for beta-ketoadipate in Pseudomonas putida

Wild-type strains of Pseudomonas putida form an inducible uptake system that appears to act on beta-ketoadipate under normal physiological conditions. The system is induced by beta-ketoadipate and is represented by catabolites derived from it. Adipate is metabolized very slowly by wild-type P. putida cultures; [14C]adipate was used as an analogue of beta-ketoadipate to measure the transport activity in wild-type cells and in cells that constitutively produced the uptake system. Constitutive cells that contained high levels of the uptake system concentrated adipate to a level up to 200-fold above the concentration in the external medium. The process was energy dependent. The activity of the system with radioactive adipate was inhibited by beta-ketoadipate, by beta-ketoadipate analogues, and by some compounds (e.g., acetate, glucose) that are structurally unrelated to beta-ketoadipate; it is not known if the inhibitory effects are exerted directly by the compounds themselves or indirectly by catabolites derived from the compounds. The discovery of the beta-ketoadipate uptake system is surprising in view of earlier studies that had indicated that beta-ketoadipate does not permeate the membrane of wild-type P. putida cells. Contradictions between the former investigations and the present analysis are due primarily to the relatively high concentrations of substrate used in the earlier experiments. The existence of the beta-ketoadipate uptake system indicates that beta-ketoadipate may exist as a selective nutrient in the natural niche of P. putida and may play a determinative role in the evolution of induction mechanisms that are characteristic of fluorescent pseudomonads.</jats:p