Molecular characterization of three 3-ketosteroid-Δ(1)-dehydrogenase isoenzymes of Rhodococcus ruber strain Chol-4.

Rhodococcus ruber strain Chol-4 isolated from a sewage sludge sample is able to grow on minimal medium supplemented with steroids, showing a broad catabolic capacity. This paper reports the characterization of three different 3-ketosteroid-Δ(1)-dehydrogenases (KstDs) in the genome of R. ruber strain Chol-4.

The strengths and weaknesses of Gordonia: a review of an emerging genus with increasing biotechnological potential.

This review about the genus Gordonia provides a current overview of recent research on a young genus that was introduced in the year 1997 ( Stackebrandt et al., 1997 ). This emerging genus has attracted increasing environmental, industrial, biotechnological and medical interest during the last few years, in particular due to the capabilities of its members to degrade, transform, and synthesize organic compounds as well as to the pathogenic effects that have been described in many case studies.

Cholesterol degradation by Gordonia cholesterolivorans.

This paper reports physiological and genetic data about the type strain Gordonia cholesterolivorans, a strain that is able to degrade steroid compounds containing a long carbon side chain such as cholesterol (C(27)), cholestenone (C(27)), ergosterol (C(28)), and stigmasterol (C(29)). The length of the carbon side chain appears to be of great importance for this bacterium, as the strain is unable to grow using steroids with a shorter or nonaliphatic carbon side chain such as cholic acid (C(24)), progesterone (C(21)), testosterone, androsterone, 4-androstene-3,17-dione (all C(19)), and further steroids. This study also demonstrates that the degradation of cholesterol is a quite common feature of the genus Gordonia by comparing Gordonia cholesterolivorans with some other species of this genus (e.

ChoG is the main inducible extracellular cholesterol oxidase of Rhodococcus sp. strain CECT3014.

Cholesterol catabolism has been reported in different bacteria and particularly in several Rhodococcus species, but the genetic of this complex pathway is not yet very well defined. In this work we report the isolation and sequencing of a 9.8 kb DNA fragment of Rhodococcus sp.

Morphological, physiological, and molecular characterization of a newly isolated steroid-degrading actinomycete, identified as rhodococcus ruber strain Chol-4.

The aerobic degradation of cholesterol, testosterone, androsterone, progesterone, and further steroid compounds as sole carbon source has been observed in the newly isolated bacterial Gram-positive strain Chol-4. The 16S rRNA gene sequence shares the greatest similarity with members of the genus Rhodococcus, with the closest shared nucleotide identities of 98-99% with Rhodococcus ruber (DSM 43338(T)) and Rhodococcus aetherivorans (DSM 44752(T)). Phylogenetic analysis of Rhodococcus 16S rRNA gene sequences consistently places strain Chol-4 in a clade shared with those both type strains within the Rhodococcus rhodochrous subclade.

Gordonia cholesterolivorans sp. nov., a cholesterol-degrading actinomycete isolated from sewage sludge.

The taxonomic position of the cholesterol-degrading strain Chol-3(T), isolated from a sewage sludge sample, was clarified using a polyphasic taxonomic approach. Phylogenetic analysis of its 16S rRNA gene sequence, whole-cell fatty acid profile and mycolic acid composition revealed that this isolate is a member of the genus Gordonia with the species Gordonia sihwensis, G. hydrophobica and G.

Identification of oxidized TNT metabolites in soil samples of a former ammunition plant.

Water extracts of soil samples of the former ammunition plant "Tanne" near Clausthal-Zellerfeld, Lower Saxony, Germany, were investigated for highly polar oxidized 2,4,6-trinitrotoluene (TNT) metabolites. 0.4 to 9.

Genetic analysis of phenylacetic acid catabolism in Arthrobacter oxydans CECT386.

Arthrobacter oxydans CECT386 is a Gram-positive bacterium able to use either phenylacetic acid or phenylacetaldehyde as the sole carbon and energy source for aerobic growth. Genes responsible for the catabolism of these compounds have been located at two chromosomal regions and were organized in one isolated paaN gene and two putative paa operons, one consisting of the paaD, paaF, tetR and prot genes, and one consisting of the paaG, paaH, paaI, paaJ, paaK and paaB genes. The identity of the paaF and paaN genes was supported by functional complementation experiments.

In vitro and in vivo sulfate reduction in the gut contents of the termite Mastotermes darwiniensis and the rose-chafer Pachnoda marginata.

Sulfate-reducing bacteria (SRB) from termites have been assigned to the genus Desulfovibrio. Desulfovibrio intestinalis lives in the gut of the Australian termite Mastotermes darwiniensis. For the first time we were able to enrich and identify a sulfate-reducing bacterium from the gut of the rose-chafer Pachnoda marginata, which showed the highest 16S rDNA sequence identity (93%) to Desulfovibrio intestinalis and Desulfovibrio strain STL1.

Diphenylamine and derivatives in the environment: a review.

Diphenylamine (DPA) is a compound from the third European Union (EU) list of priority pollutants. It was assigned by the EU to Germany to assess and control its environmental risks. DPA and derivatives are most commonly used as stabilizers in nitrocellulose-containing explosives and propellants, in the perfumery, and as antioxidants in the rubber and elastomer industry.

Dehalogenation of chlorinated ethenes and immobilization of nickel in anaerobic sediment columns under sulfidogenic conditions.

A sediment column study was carried out to demonstrate the bioremediation of chloroethene- and nickel-contaminated sediment in a single anaerobic step under sulfate-reducing conditions. Four columns (one untreated control column and three experimental columns) with sediment from a chloroethene- and nickel-contaminated site were investigated for 1 year applying different treatments. By stimulating the activity of sulfate-reducing bacteria by the addition of sulfate as supplementary electron acceptor, complex anaerobic communities were maintained with lactate as electron donor (with or without methanol), which achieved complete dehalogenation of tetra- and trichloroethenes (PCE and TCE) to ethene and ethane.

Tetrachloroethene dehalorespiration and growth of Desulfitobacterium frappieri TCE1 in strict dependence on the activity of Desulfovibrio fructosivorans.

Tetrachloroethene (PCE) dehalorespiration was investigated in a continuous coculture of the sulfate-reducing bacterium Desulfovibrio fructosivorans and the dehalorespiring Desulfitobacterium frappieri TCE1 at different sulfate concentrations and in the absence of sulfate. Fructose (2.5 mM) was the single electron donor, which could be used only by the sulfate reducer.

Coexistence of a sulphate-reducing Desulfovibrio species and the dehalorespiring Desulfitobacterium frappieri TCE1 in defined chemostat cultures grown with various combinations of sulfate and tetrachloroethene.

A two-member co-culture consisting of the dehalorespiring Desulfitobacterium frappieri TCE1 and the sulphate-reducing Desulfovibrio sp. strain SULF1 was obtained via anaerobic enrichment from soil contaminated with tetrachloroethene (PCE). In this co-culture, PCE dechlorination to cis-dichloroethene was due to the activity of the dehalorespiring bacterium only.

Reclassification of Desulfobacterium phenolicum as Desulfobacula phenolica comb. nov. and description of strain SaxT as Desulfotignum balticum gen. nov., sp. nov.

A mesophilic, sulfate-reducing bacterium (strain SaxT) was isolated from marine coastal sediment in the Baltic Sea and originally described as a 'Desulfoarculus' sp. It used a large variety of substrates, ranging from simple organic compounds and fatty acids to aromatic compounds as electron donors. Autotrophic growth was possible with H2, CO2 and formate in the presence of sulfate.

Influence of different electron donors and acceptors on dehalorespiration of tetrachloroethene by Desulfitobacterium frappieri TCE1.

Strain TCE1, a strictly anaerobic bacterium that can grow by reductive dechlorination of tetrachloroethene (PCE) and trichloroethene (TCE), was isolated by selective enrichment from a PCE-dechlorinating chemostat mixed culture. Strain TCE1 is a gram-positive, motile, curved rod-shaped organism that is 2 to 4 by 0.6 to 0.

Anaerobic incorporation of the radiolabeled explosive TNT and metabolites into the organic soil matrix of contaminated soil after different treatment procedures.

Four bioreactor designs were performed to evaluate the level of incorporation of 14C-labeled 2,4,6-trinitrotoluene (TNT) and metabolites into the organic soil matrix of different anaerobically treated contaminated soils. The contaminated soils were amended with molasses slivers (80:20% per weight) as auxiliary substrate to enhance microbial activity. After 5 weeks (bioreactors 1 and 2), 8 weeks (bioreactor 3) and 12 weeks (bioreactor 4) of anaerobic incubation, we determined 41%, 58%, 72%, and 54%, respectively, of the initially applied radioactivity immobilized in various soil fractions.

Mass balance studies with 14C-labeled 2,4,6-trinitrotoluene (TNT) mediated by an Anaerobic desulfovibrio species and an Aerobic serratia species.

Investigations were carried out to evaluate the level of incorporation of radiolabeled 2,4,6-trinitrotoluene (TNT) and metabolites into the bacterial biomass of two different bacterial species after cometabolically mediated TNT transformation. Biotransformation experiments with 14C-TNT indicated that TNT was not mineralized; however, carbon derived from TNT became associated with the cells. It was found that more than 42% of the initially applied radiolabel was associated with the cell biomass after cometabolic 14C-TNT transformation with the strictly anerobic Desulfovibrio species strain SHV, whereas with the strictly aerobic Serratia plymuthica species strain B7, 32% of cell-associated 14C activity was measured.

Microbial Degradation of Diphenylamine Under Anoxic Conditions.

Diphenylamine (DPA) was cometabolically degraded in anoxic sediment-water batch enrichments and in cultures of newly isolated sulfate-reducing bacteria. In gas chromatography-mass spectrometry (GC-MS) measurements, aniline was identified as a major breakdown product of the diphenylamine structure. After its identification, aniline was quantified by reversed phase high pressure liquid chromatography (HPLC).

Cometabolic transformation and cleavage of nitrodiphenylamines by three newly isolated sulfate-reducing bacterial strains.

Three sulfate-reducing bacterial strains (Desulfovibrio sp. strain SHV, Desulfococcus sp. strain WHC, and Desulfomicrobium sp.

Reduction of Nitrated Diphenylamine Derivatives under Anaerobic Conditions.

2-Nitrodiphenylamine, 4-nitrodiphenylamine, and 2,4-dinitrodiphenylamine were anaerobically metabolized in sediment-water batch enrichments inoculated with mud from the German North Sea coast. The first intermediate in 2,4-dinitrodiphenylamine degradation was 2-amino-4-nitrodiphenylamine, which appeared in large (nearly stoichiometric) amounts before being completely reduced to 2,4-diaminodiphenylamine. Of the second theoretically expected metabolite, 4-amino-2-nitrodiphenylamine, only traces were detected by gas chromatographic-mass spectrometric analysis in highly concentrated extracts.

Toxicity of diphenylamine and some of its nitrated and aminated derivatives to the luminescent bacterium Vibrio fischeri.

Aqueous samples containing various nitrated and aminated diphenylamine derivatives were subjected to the luminescent bacterium Vibrio fischeri NRRL-B-11177 to determine their ecotoxicological potential. As the most important toxicological parameter, EC50, the concentration needed to reduce bacterial luminescence by 50%, was calculated. All compounds tested must be classified to the category "very toxic to aquatic organisms" using the widely accepted classification scheme of D.

Mineralization of monofluorobenzoate by a diculture under sulfate-reducing conditions.

A mesophilic, dehalogenating, sulfate-reducing diculture was isolated from an anaerobic lake sediment. One strain of the diculture is proposed to be an endospore-forming Desulfotomaculum species, the second strain was a vibrioid, motile and non-sporeforming species which is tentatively assigned to the genus Desulfovibrio. The diculture was able to mineralize 4- and 2-fluorobenzoate both isomers being incompletely oxidized with the release of acetate, which was subsequently used by both sulfate-reducing strains.

Microbial degradation of explosives and related compounds.

The pollution of soil and water with explosives and related compounds caused by military activities has been known for a long time, but progress in understanding the environmental fate of such substances has only been made in the last few years. Microbial processes could be used for the remediation of explosives-contaminated soils and waste waters because it has been shown that a variety of different microorganisms are able to metabolize these chemical compounds. In some cases even a complete mineralization has been found, whereas in others only biotransformation reactions took place, producing more or less toxic and/or recalcitrant metabolites.

Complete oxidation of benzoate and 4-hydroxybenzoate by a new sulfate-reducing bacterium resembling Desulfoarculus.

A new sulfate-reducer "strain SAX" was isolated from an anaerobic marine sediment [Saxild, Denmark]. The isolate was a gram-negative, motile and non-spore-forming rod which sometimes appeared as a curved rod. Strain SAX differed from all described Desulfovibrio-, Desulfobotulus- and Desulfoarculus-species by the ability to degrade aromatic compounds such as benzoate, 4-hydroxybenzoate and phenol completely to CO2.