B. P. Baskunov

Involvement of the respiratory chain of gram-negative bacteria in the reduction of tellurite.

Abstract. The terminal oxidases of the respiratory chain of seven strains of gram-negative bacteria were shown to be involved in the reduction of tellurite. The rate of tellurite reduction correlated with the intensity of respiration. The inhibitors of terminal oxidases, carbon monoxide and cyanide, inhibited the reduction of tellurite. In Pseudomonas aeruginosa PAO ML4262 and P. aeruginosa PAO ML4262 (pBS10), the respiratory chain was found to contain three types of cytochrome c, one of which (the carbon monoxide-binding cytochrome c) was involved in the reduction of tellurite. Agrobacterium tumefaciens VKM B-1219, P. aeruginosa IBPM B-13, and Escherichia coli G0-102bd++ cells contained oxidases aa3, bb3, and bd, respectively. The respiratory chain of other strains contained two oxidases: E. coli DH5α of bb3- and bd-type, and Erwinia carotovora VKM B-567 of bo3- and bd-type. All the strains under study reduced tellurite with the formation of tellurium crystallites. Depending on the position of the active center of terminal oxidases in the plasma membrane, the crystallites appeared either in the periplasmic space [P. aeruginosa PAO ML4262 and P. aeruginosa PAO ML4262 (pBS10)], or on the outer surface of the membrane (A. tumefaciens VKM B-1219 and P. aeruginosa IBPM B-13), its inner surface (E. coli G0-102bd++), or on both surfaces (E. coli DH5α and E. carotovora VKM B-567).

Degradation of polychlorinated phenols by Streptomyces rochei 303

The strain Streptomyces rochei 303 (VKM Ac-1284D) is capable of utilizing 2-chloro-,2,4-,2,6-dichloro- and 2,4,6-trichlorophenols as the sole source of carbon. Its resting cells completely dechlorinated and degraded 2-, 3-chloro-; 2,4-, 2,6-, 2,3-, 2,5-, 3,4-, 3,5-dichloro-; 2,4-, 2,6-dibromo-; 2,4,6-, 2,4,5-, 2,3,4-, 2,3,5-, 2,3,6-trichlorophenols; 2,3,5,6-tetrachloro- and pentachlorophenol. During chlorophenol degradation, a stoichiometric amount of chloride ions was released and chlorohydroquinols were formed as intermediates. In cell-free extracts of S. rochei, the activity of hydroxyquinol 1,2-dioxygenase was found. The enzyme was induced with chlorophenols. Of all so far described strains degrading polychlorophenols, S. rochei 303 utilized a wider range of chlorinated phenols as the sole sourse of carbon and energy.

Conversion of polycyclic aromatic hydrocarbons by Sphingomonas sp. VKM B-2434

A versatile bacterial strain able to convert polycyclic aromatic hydrocarbons (PAHs) was isolated, and a conversion by the isolate of both individual substances and PAH mixtures was investigated. The strain belonged to the Sphingomonas genus as determined on the basis of 16S rRNA analysis and was designated as VKM B-2434. The strain used naphthalene, acenaphthene, phenanthrene, anthracene and fluoranthene as a sole source of carbon and energy, and cometabolically oxidized fluorene, pyrene, benz[a]anthracene, chrysene and benzo[a]pyrene. Acenaphthene and fluoranthene were degraded by the strain via naphthalene-1,8-dicarboxylic acid and 3-hydroxyphthalic acid. Conversion of most other PAHs was confined to the cleavage of only one aromatic ring. The major oxidation products of naphthalene, phenanthrene, anthracene, chrysene, and benzo[a]pyrene were identified as salicylic acid, 1-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid, o-hydroxyphenanthroic acid and o-hydroxypyrenoic acid, respectively. Fluorene and pyrene were oxidized mainly to hydroxyfluorenone and dihydroxydihydropyrene, respectively. Oxidation of phenanthrene and anthracene to the corresponding hydroxynaphthoic acids occurred quantitatively. The strain converted phenanthrene, anthracene, fluoranthene and carbazole of coal-tar-pitch extract.

Degradation of 2,4,5-Trichlorophenoxyacetic acid by a Nocardioides simplex culture

A Nocardioides simplex strain 3E was isolated which totally dechlorinated 2,4,5-trichlorophenoxyacetic acid and was capable of its utilization as the sole source of carbon. The mechanism of 2,4,5-trichlorophenoxyacetic acid degradation by this strain was investigated. Chloroaromatic metabolites that occur in the lag, exponential and stationary growth phases of the strain Nocardioides simplex 3E were isolated and identified bases on a combination of TLC, GC-MS and HPLC data. Decomposition of 2,4,5-trichlorophenoxyacetic acid at the initial stage was shown to proceed by two pathways: via the splitting of the two-carbon fragment to yield 2,4,5-trichlorophenol and the reductive dechlorination to produce 2,4-dichlorophenoxyacetic acid. Hydrolytic dechlorination of 2,4,5-trichlorophenoxyacetic acid was found to yield dichlorohydroxyphenoxyacetic acid, thus pointing to the possible existence of a third branch at the initial stage of degradation of the xenobiotic. 2,4,5-Trichlorophenol and 2,4-dichlorophenoxyacetic acid produced during the metabolism of 2,4,5-trichlorophenoxyacetic acid and in experiments with resting cells are utilized by the strain Nocardioides simplex 3E as growth substrates.

Degradation of pentachlorophenol in soil by streptomyces rochei 303

Abstract The contact aeration treatment process is an improved activated sludge system in which sludge is not returned to the activated sludge basin. It was used to compensate the disadvantage of the activated sludge system in the three‐step piggery wastewater treatment (TPWT) process. A wave‐shaped vinyl plastic was used as biofilm support substratum for this study. The hydraulic retention time (HRT) for anaerobic fermentation step of TPWT was varied to verify the effects of contact aeration treatment process. The results showed that removal rates of biochemical oxygen demand (BOD), chemical oxygen demand (COD), and suspended solid (SS) by contact aeration treatment process in coordination with the anaerobic fermentation of TPWT process were all over 90%. Especially, both BOD and SS of effluents met the Effluent Standard for Livestock of 1998 of the R O. C. Environmental Protection Agency (EPA). For COD removal, only two experimental sets, anaerobic HRT= 4 and 7.5 days, of COD met the effluent requiremen...

Role of surfactants in optimizing fluorene assimilation and intermediate formation by Rhodococcus rhodochrous VKM B-2469

Biodegradation of fluorene by Rhodococcus rhodochrous VKM B-2469 was investigated and optimized by adding non-ionic surfactants to the liquid media. The utilization of 1-1.5% Tween 60 or 1% Triton X100 allowed to solubilize 1 mM fluorene over 150 times more than in water medium (from 9-11 microM to above 1.5 mM at 28 degrees C). We observed that Tween 60 was useful to enhance the fluorene biodegradation rates further supporting R. rhodochrous VKM B-2469 growth as an additional carbon source and to decrease fluorene toxicity for bacterial cells whereas Triton X100 resulted to be toxic for this strain. An additional enzyme induction step before starting the bioconversion process and the increase of incubation temperature during fluorene bioconversion led to further improvements in rates of fluorene utilization and formation of its intermediates. In the optimized conditions 1 mM fluorene was degraded completely within 24h of incubation. Some intermediates in fluorene degradation built up during the process reaching maxima of 31% for 9-hydroxyfluorene, 2.1% for 9-fluorenone and 1.9% for 2-hydroxy-9-fluorenone (starting from 1 mM substrate). In the presence of Tween 60 the appearance and following conversion of 2-hydroxy-9-fluorenone was observed for R. rhodochrous VKM B-2469 revealing the existence of a new pathway of 9-fluorenone bioconversion.

Identification of fluoropyrogallols as new intermediates in biotransformation of monofluorophenols in Rhodococcus opacus 1cp.

ABSTRACT The transformation of monofluorophenols by whole cells ofRhodococcus opacus 1cp was investigated, with special emphasis on the nature of hydroxylated intermediates formed. Thin-layer chromatography, mass spectrum analysis, and 19F nuclear magnetic resonance demonstrated the formation of fluorocatechol and trihydroxyfluorobenzene derivatives from each of three monofluorophenols. The 19F chemical shifts and proton-coupled splitting patterns of the fluorine resonances of the trihydroxyfluorobenzene products established that the trihydroxylated aromatic metabolites contained hydroxyl substituents on three adjacent carbon atoms. Thus, formation of 1,2,3-trihydroxy-4-fluorobenzene (4-fluoropyrogallol) from 2-fluorophenol and formation of 1,2,3-trihydroxy-5-fluorobenzene (5-fluoropyrogallol) from 3-fluorophenol and 4-fluorophenol were observed. These results indicate the involvement of fluoropyrogallols as previously unidentified metabolites in the biotransformation of monofluorophenols in R. opacus1cp.

Phenanthrene and anthracene degradation by microorganisms of the genus Rhodococcus

The cells of Rhodococcus opacus 412 and R. rhodnii 135 were adapted to phenanthrene and anthracene on a solid mineral medium. Preliminary adaptation of the strains accelerated the metabolism of polyaromatic hydrocarbons and provided for the ability of microorganisms to grow on pheanthrene as a sole carbon and energy source in a liquid mineral medium. It was shown that phenanthrene was mineralized by the strains through 7,8-benzocoumarin, 1-hydroxy-2-naphthoaldehyde, 1-hydroxy-2-naphthoic acid, salicylaldehyde, salicylate and catechol to the intermediates of tricarbonic acid cycle and partially transformed with the accumulation of the products of subsequent monooxygenation (3-hydroxyphenanthrene and phenanthrene dihydroxylated not in ortho-position). As a result of the adaptation of the strains to anthracene on a solid mineral medium, the obtained variant of strain R. opacus 412 was able to transform anthracene in a liquid mineral medium to anthraquinone and 6,7-benzocoumarin.

Degradation of phenanthrene by the rhizobacterium Ensifer meliloti.

The biodegradation of the polycyclic aromatic hydrocarbon phenantherene by the rhizobacterial strain Ensifer meliloti P221, isolated from the root zone of plant grown in PAH-contaminated soil was studied. Bacterial growth and phenanthrene degradation under the influence of root-exuded organic acids were also investigated. Analysis of the metabolites produced by the strain by using thin-layer chromatography, gas chromatography, high-pressure liquid chromatography, and mass-spectrometry revealed that phenanthrene is bioconverted via two parallel pathways. The first, major pathway is through terminal aromatic ring cleavage (presumably at the C3–C4 bond) producing benzocoumarin and 1-hydroxy-2-naphthoic acid, whose further degradation with the formation of salicylic acid is difficult or is very slow. The second pathway is through the oxidation of the central aromatic ring at the C9–C10 bond, producing 9,10-dihydro-9,10-dihydroxyphenanthrene, 9,10-phenanthrenequinone, and 2,2′-diphenic acid. This is the first time that the dioxygenation of phenanthrene at the C9 and C10 atoms, proven by identification of characteristic metabolites, has been reported for a bacterium of the Ensifer genus.

The Microbial Transformation of Phenanthrene and Anthracene

The transformation of phenanthrene and anthracene by Rhodococcus rhodnii 135, Pseudomonas fluorescens 26K, and Arthrobacter sp. K3 is studied. Twenty-one intermediates of phenanthrene and anthracene transformation are identified by HPLC, mass spectrometry, and NMR spectroscopy. P. fluorescens 26K and Arthrobacter sp. K3 are found to produce a wide range of intermediates, whereas R. rhodnii 135 oxidizes phenanthrene, resulting in the formation of a sole product, 3-hydroxyphenanthrene. Putative transformation pathways of phenanthrene and anthracene are proposed for the three bacterial strains studied. These strains can be used to obtain valuable compounds (such as hydroxylated polycyclic aromatic hydrocarbons) that are difficult to produce by chemical synthesis.