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E L Golovlev

Publications and source records attributed to E L Golovlev.

At least 19 recordsLinked to original sources
PubMed2001

Purification and properties of p-hydroxybenzoate hydroxylases from Rhodococcus strains.

Gram-positive bacteria of the genus Rhodococcus catabolize p-hydroxybenzoate (PHB) through the initial formation of 3,4-dihydroxybenzoate. High levels of p-hydroxybenzoate hydroxylase (PHBH) activity are induced in six different Rhodococcus species when these strains are grown on PHB as sole carbon source. The PHBH enzymes were purified to apparent homogeneity and appeared to be homodimers of about 95 kD with each subunit containing a relatively weakly bound FAD. In contrast to their counterparts from gram-negative microorganisms, the Rhodococcus PHBH enzymes prefer NADH to NADPH as external electron donor. All purified enzymes were inhibited by Cl- and for five of six enzymes more pronounced substrate inhibition was observed in the presence of chloride ions.

4-Hydroxybenzoate-3-Monooxygenase↗
PubMed2000

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

The transformation of monofluorophenols by whole cells of Rhodococcus opacus 1cp was investigated, with special emphasis on the nature of hydroxylated intermediates formed. Thin-layer chromatography, mass spectrum analysis, and (19)F nuclear magnetic resonance demonstrated the formation of fluorocatechol and trihydroxyfluorobenzene derivatives from each of three monofluorophenols. The (19)F 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. opacus 1cp.

Biotransformation↗
PubMed1999

Preferential oxidative dehalogenation upon conversion of 2-halophenols by Rhodococcus opacus 1G.

The regiospecificity of hydroxylation of C2-halogenated phenols by Rhodococcus opacus 1G was investigated. Oxidative defluorination at the C2 position ortho with respect to the hydroxyl moiety was preferred over hydroxylation at the non-fluorinated C6 position for all 2-fluorophenol compounds studied. Initial hydroxylation of 2,3, 5-trichlorophenol resulted in the exclusive formation of 3, 5-dichlorocatechol. These results indicate that, in contrast to all other phenol ortho-hydroxylases studied so far, phenol hydroxylase from R. opacus 1G is capable of catalyzing preferential oxidative defluorination but also oxidative dechlorination.

Biodegradation, Environmental↗
PubMed1999

Isolation and characterization of catechol 1,2-dioxygenases from Rhodococcus rhodnii strain 135 and Rhodococcus rhodochrous strain 89: comparison with analogous enzymes of the ordinary and modified ortho-cleavage pathways.

Catechol 1,2-dioxygenases of the ordinary ortho-cleavage pathway have been isolated from strains Rhodococcus rhodnii 135 and Rhodococcus rhodochrous 89 grown on phenol as the sole source of carbon and energy. The activities of the catechol 1,2-dioxygenases with 3- and 4-methylpyrocatechols were 1.3-1.5 times higher than those with pyrocatechol. The rate of oxidation of 3-chloropyrocatechol catalyzed by both enzymes was 20% of the rate of oxidation of unsubstituted pyrocatechol. The enzymes are homodimers composed of 37-kD subunits.

Catechol 1,2-Dioxygenase↗
PubMed1998

19F NMR study on the biodegradation of fluorophenols by various Rhodococcus species.

Of all NMR observable isotopes 19F is the one perhaps most convenient for studies on biodegradation of environmental pollutants. The reasons underlying this potential of 19F NMR are discussed and illustrated on the basis of a study on the biodegradation of fluorophenols by four Rhodococcus strains. The results indicate marked differences between the biodegradation pathways of fluorophenols among the various Rhodococcus species. This holds not only for the level and nature of the fluorinated biodegradation pathway intermediates that accumulate, but also for the regioselectivity of the initial hydroxylation step. Several of the Rhodococcus species contain a phenol hydroxylase that catalyses the oxidative defluorination of ortho-fluorinated di- and trifluorophenols. Furthermore, it is illustrated how the 19F NMR technique can be used as a tool in the process of identification of an accumulated unknown metabolite, in this case most likely 5-fluoromaleylacetate. Altogether, the 19F NMR technique proved valid to obtain detailed information on the microbial biodegradation pathways of fluorinated organics, but also to provide information on the specificity of enzymes generally considered unstable and, for this reason, not much studied so far.

Biodegradation, Environmental↗
PubMedDate not supplied

[Degradation of herbicide Alvison-8 by microorganisms].

Microbial degradation of a new herbicide, Alvison-8, was studied. No strains capable of growth at the account of this compound as a source of carbon have been found among microorganisms isolated from soil treated with the herbicide and among collection cultures. Some strains can degrade Alvison-8 at a concentration of 100-300 mg/litre in cooxidative conditions. Effective cosubstrates are such compounds which are actively metabolized by microorganisms but cannot maintain intensive growth. In some cases, the cultures grew at the account of cosubstrates and the process consisted of two stages, i. e. degradation occured at the beginning prior to the phase of active growth.

Bacteria↗
PubMedDate not supplied

[Introduction to the biology of the bacterial stationary phase: mechanism of general response to stress].

This review is devoted to the biology of stationary-phase bacteria, occurring in a specific physiological state at which they arrive in the process of complex response to various kinds of stresses accompanying the retardation and cessation of growth and reproduction. A general account of the problem is presented. Special emphasis is placed on one of the metabolic mechanisms involved in the formation of the physiological state of stationary-phase bacteria and performing primarily protective functions (the so-called general response of cells to stresses). The relationship between this and other regulatory mechanisms involved in the transition of bacteria to the stationary phase and the maintenance of this phase is discussed.

Bacteria↗
PubMedDate not supplied

[Physiology of microbial cell and metabolic engineering].

This review is devoted to the problems of the physiology and cell biology of microorganisms in relation to metabolic engineering. The latter is considered as a branch of fundamental and applied biotechnology aimed at controlling microbial metabolism by methods of genetic engineering and classical genetics and based on intimate knowledge of cell metabolism. Attention is also given to the problems associated with the metabolic limitation of microbial biosyntheses, analysis and control of metabolic fluxes, rigidity of metabolic pathways, the role of pleiotropic (global) regulatory systems in the control of metabolic fluxes, and prospects of physiological and evolutionary approaches in metabolic engineering.

Genetic Engineering↗
PubMedDate not supplied

[General and molecular ecology of Legionella].

The review is devoted to the general and molecular ecology of bacteria of the genus Legionella in natural and anthropogenic environments. Invasion of amoebae and infusoria by legionellae and their replication in these protozoa can be considered to be a pre-adaptation for invasion of the human immune system. Symbiosis of bacteria and protozoa as a promising model of cellular microbiology and the conception of bacterial ecological niches are discussed in relation to the low fidelity of most bacterial species to their habitats (biotopes). The necessity of elaboration of a similar conception for microbial consortia and associations is emphasized.

Animals↗
PubMedDate not supplied

[Dependence of transformation of chlorophenols by Rhodococci on position and number of chlorine atoms in the aromatic ring].

Study of the conversion of chlorophenols by Rhodococcus opacus 1G, R. rhodnii 135, R. rhodochrous 89, and R. opacus 1cp disclosed the dependence of the conversion rate and pathway on the number and position of chlorine atoms in the aromatic ring. The most active chlorophenol converter, strain R. opacus 1cp, grew on each of the three isomeric monochlorophenols and on 2,4-dichlorophenol; the rate of growth decreased from 4-chlorophenol to 3-chlorophenol and then to 2-chlorophenol. The parameters of growth on 2,4-dichlorophenol were the same as on 3-chlorophenol. None of the strains studied utilized trichlorophenols. A detailed study of the pathway of chlorophenol transformation showed that 3-chloro-, 4-chloro-, and 2,4-dichlorophenol were utilized by the strains via a modified ortho-pathway. 2-Chlorophenol and 2,3-dichlorophenol were transformed by strains R. opacus 1cp and R. rhodochrous 89 via corresponding 3-chloro- and 3,4-dichloropyrocatechols, which were then hydroxylated with the formation of 4-chloropyrogallol and 4,5-dichloropyrogallol; this route had not previously been described in bacteria. Phenol hydroxylase of R. opacus 1G exhibited a previously undescribed catalytic pattern, catalyzing oxidative dehalogenation of 2,3,5-trichlorophenol with the formation of 3,5-dichloropyrocatechol but not hydroxylation of the nonsubstituted position 6.

Biotransformation↗
PubMedDate not supplied

[Enzymes of intermediary metabolism in coryneform bacteria].

Enzymes of the intermediate metabolism were studied in ten strains of Corynebacterium-like organisms belonging to the genera Arthrobacter, Brevibacterium, Corynebacterium and Nocardia. All of these were found to contain enzymes of the glycolytic pathway, and nine strains among ten had dehydrogenases of the pentose phosphate shunt. The activity of enzymes of the citric acid cycle was low: alpha-ketoglutarate dehydrogenase was not found in Arthrobacter, Corynebacterium, Brevibacterium linens and Nocardia minima. Eight strains possessed the activity of the key enzyme of the gamma-aminobutyrate shunt, i.e. gamma-aminobutyrate aminotransferase. The activity of enzymes of the glyoxylate shunt was found in nine strains, and their level was rather high even during growth on glucose. Therefore, it is possible to study the taxonomic structure of this group of microorganisms by analyzing the composition and the level of enzymes involved in the intermediate metabolism. The competence of the Brevibacterium genus is corroborated by the typical species Brevibact. linens, as well as the reality of saprophytic representatives of the Corynebacterium genus, and a special taxonomic position of the group Brevibact. ammoniagenes--Brevibact. stationis.

Actinomycetales↗
PubMedDate not supplied

Decomposition of DDT and its analogs by soil microflora.

A search was made for active cultures that break down DDT. More than 600 microorganisms were isolated from soils treated for a long time with DDT and from accumulating cultures with DDT or its analogs as the carbon source and with DDT or its analogs and supplementary carbon sources. Cultures capable of degrading DDT under conditions of cometabolism were found among them. It was shown that the dechlorination of the trichloromethyl group of DDT was accomplished by a large number of microorganisms and occurred primarily under conditions of limited aeration. The elimination of chloride ions from the aromatic rings occurred only in the presence of cosubstrates under aerobic conditions and only with two strains. The strain Nocardia sp. 306x carried out complete degradation of DDT with the formation of DBH, DCBP, and an as yet unidentified entirely dechlorinated product. The most profound decomposition of DDT was produced by a culture of Ps. aeruginosa 640x, which entirely degraded the DDT molecule with the formation of phenylacetic acid.

Biodegradation, Environmental↗