[Effect of lipolytic and catalase activity on physico-mechanical properties of coating Polyken 980-25].

Lipolytic and catalase activity of Pseudomonas pseudoalcaligenes 109, Rhodococcus erythropolis 102, Bacillus subtilis 138 and their association with different growth models: biofilm and plankton ones. It is shown that under biofilm conditions the fermentative activity of bacteria under study was 1.5-1.7 times higher than under plankton conditions. Monocultures of bacteria displayed much lower activity than associative ones. Changes of physico-chemical properties of the specimens of protective coating Polyken 980-25 with participation of the above bacteria have been studied. The coating breaking strength decreases by 5.9-11.8% under the effect of monocultures, and by 17.3% under the effect of association. The adhesive strength as the basic index of coating biologic resistance decreased, respectively, in mono- and associated cultures by 28.6-73.2% in respect of the control. Damaging the sticking layer of isolation coating, bacteria damage the adhesion to metal which favors its corrosion.

[Monosaccharide and fatty acid composition of exopolymer complex of bacteria-destructors of the protective coating of gas pipeline].

Monosaccharide and fatty acid composition of the exopolymer complex (EPC) of heterotrophic bacteria Pseudomonas pseudoalkaligenes 109, Pseudomonas sp. T/2, Rhodococcus erythropolis 102--destructors of the protective coating Polyken 980-25 has been studied. It is shown that qualitative and quantitative composition of EPC components changes depending on the model of bacteria growth. Arabinose, mannose, galactose and glucose are dominating saccharides. Xylose has been revealed only under conditions of the biofilm form of growth of all the studied bacteria; ribose only in the biofilm of Pseudomonas sp. T/2. The fatty acid composition of EPC contains saturated and unsaturated acids with 12-19 carbon atoms. Hexadecanoic acid (C 16:0) acid which content in the biofilm and plankton conditions is from 24.9 to 32.4% prevailed in the spectrum of fatty acids of EPC bacteria. Unsaturated fatty acids: hexadecanoic (C 16:1) and octadecenoic (C 18:1) ones have been revealed only in the biofilm of bacteria-destructors of the coating.

[Lipolytic and catalase activity of bacteria-destructors of protective coatings].

Lipolytic and catalase activity of bacteria-destructors of protective coatings at different growth models: biofilm and plankton have been studied. It was shown that the synthesis of exoenzymes in the biofilm is different. Activity of extracellular lipase and catalase in the biofilm is 1.1-1.5 and 1.2-2.1 times higher, respectively, than in plankton. The experiment duration being increased to 14 days, the lipolytic activity considerably decreases. Activity of studied enzymes, produced by bacteria-destructors, can be used for estimating bioresistance of isolating coatings as the index of their biodegradation in technogenic media.

[Methods for estimation of microbe resistance of protective coatings]. / Metody otsenki mikrobnoi stoikosti zashchitnykh pokrytii.

Methods are proposed which permit estimating bioresistance of protective materials against denitrifying hydrocarbon-oxidizing and sulphate-reducing bacteria-destructors of coatings in laboratory conditions. The methods are based on the quantitative determination of bacteria growth in presence of coatings as the only source of hydrocarbon. Besides, attention is given to changes of certain indices of physico-mechanical properties of coatings: breaking strength and adhesion strength for coatings from polymeric bands, softening and expansion temperature for mastic materials.

[Formation of microbial populations on the surface of protective coatings]. / Formirovanie mikrobnykh soobshchestv na poverkhnosti zashchitnykh pokrytii.

Formation of microbial cenosis on the surface of polyethylene-, polyurethane- and oil-bitumen-based protective coatings was studied in dynamics during 1, 3, 7, 14 and 21 days. It has been shown that the biofilm was formed on the protective materials during 14 days and consisted of ammonifying, denitrifying, hydrocarbon-oxidizing and sulphate-reducing bacteria referred to Pseudomonas, Arthrobacter, Bacillus and Kesulfovibrio genera. The bacteria which form the biofilm on coatings possess high denitrifying and sulphate-reducing activities. Corrosion inhibitors-biocydes, introduced in composition of oil-bitumen coatings suppressed growth and metabolic activity of corrosion-active bacteria.

Mercury resistance transposons of gram-negative environmental bacteria and their classification.

A total of 29 mercury resistance transposons were isolated from mercury-resistant environmental strains of proteobacteria collected in different parts of Eurasia and the USA and tested for hybridization with probes specific for transposase genes of known mercury resistance transposons. 9 were related to Tn21 in this test, 12 were related to Tn5053, 4 to Tn5041 and 1 to Tn5044; three transposons were negative in this test. Restriction mapping and DNA sequencing revealed that 12 transposons were identical or nearly identical to their corresponding relatives while the rest showed varying divergence from their closest relatives. Most of these previously unknown transposons apparently arose as a result of homologous or site-specific recombination. One of these, Tn5046, was completely sequenced, and shown to be a chimera with the mer operon and the transposition module derived from the transposons related to Tn5041 and to Tn5044, respectively. Transposon Tn5070, showing no hybridization with the specific probes used in this study, was also completely sequenced. The transposition module of Tn5070 was most closely related to that of Tn3 while the mer operon was most closely related to that of plasmid pMERPH. The merR of Tn5070 is transcribed in the same direction as the mer structural genes, which is typical for mer operons of gram-positive bacteria. Our data suggest that environmental bacteria may harbor many not yet recognized mercury resistance transposons and warrant their further inventory.

Tn5041: a chimeric mercury resistance transposon closely related to the toluene degradative transposon Tn4651.

This paper reports the discovery and characterization of Tn5041, a novel-type transposon vehicle for dissemination of mercury resistance in natural bacterial populations. Tn5041 (14876 bp), identified in a Pseudomonas strain from a mercury mine, is a Tn3 family mercury resistance transposon far outside the Tn21 subgroup. As in other Tn3 family transposons, Tn5041 duplicates 5 bp of the target sequence following insertion. Tn5041 apparently acquired its mer operon as a single-ended relic of a transposon belonging to the classical mercury resistance transposons of the Tn21 subgroup. The putative transposase and the 47 bp terminal inverted repeats of Tn5041 are closely related to those of the toluene degradative transposon Tn4651 and fall into a distinct subgroup on the fringe of the Tn3 family. The amino acid sequence of the putative resolvase of Tn5041 resembles site-specific recombinases of the integrase family. Besides the mer operon and putative transposition genes, Tn5041 contains a 4 kb region that accommodates a number of apparently defective genes and mobile elements.

[Incorporation of Tn5053 and Tn402 into various plasmids]. / Izuchenie vstraivaniia Tn5053 i Tn402 v razlichnye plazmidy.

Transposons Tn5053 and Tn402 that belong to the novel family of Tn elements are characterized by high selectivity when choosing a target. These transposons integrated with a high frequency into only two of seven large plasmids of various incompatibility groups: RP1 and R446b. The res region of the RP1 plasmid par locus and the res region of the transposon Tn701, included into R446b plasmid, served as targets for both transposons. When Tn701 or par locus integrated into plasmids previously unsuitable for Tn5053 and Tn402 transposition, these plasmids became good targets for both transposons. On the contrary, when the res region of RP1 was damaged impaired, this good target became unsuitable. The insertion sites of Tn5053 and Tn402 were concentrated in the res region of Tn1721 and RP1, but, in some cases, they were at a distance of 100-2000 bp from it.

[Expression of the nif and ntr genes of Klebsiella pneumoniae in Rhodobacter sphaeroides cells]. / Issledovanie ékspressii nif- i ntr-genov Klebsiella pneumoniae v kletkakh Rhodobacter sphaeroides.

The genes glnA, ntr, nif or their promoters from Klebsiella pneumoniae cloned on the vectors, based on the plasmid RSF1010, were introduced into Rhodobacter sphaeroides cells. It was found that K. pneumoniae genes glnA, nifB, nifE, nifL and nifH are not expressed in R. sphaeroides. Neither was the glnA gene from cyanobacterium Anabaena 7120 expressed in R. sphaeroides. No functional activity of K. pneumoniae product of ntrA gene which is expressed from its own promoter, and the product of the gene nifA which is expressed from the constitutive promoter of the kanamycin resistance gene of the transposon Tn903, was detected. The implications of these findings are discussed.

[Characteristics of lysine transport in a wild type strain and lysine-producing mutant of Corynebacterium glutamicum]. / Osobennosti transporta lizina v kletki shtamma Corynebacterium glutamicum dikogo tipa i lizinprodutsiruiushchikh mutantov.

An active transport system high specific for 1-lysine was found in the cells of the wild strain of Corynebacterium glutamicum, Km being about 10 microM. Accumulation of lysine was higher, if the cells were cultivated on a medium containing glucose. The cells of the homoserine-deficient lysine producer have no alterations in the lysine transport. The lysine transport was also studied in three lysine producing analog resistant mutants (two mutants are resistant to aminoethylcysteine and one to lysine hydroxamate). The key enzyme of the lysine biosynthesis, aspartate kinase, is insensitive to the feedback inhibition by the mixture of lysine and threonine in all the mutant studied; at the same time the cells of these mutants grown on a glucose-containing medium above mentioned alterations are suggested to provide the resistance to the lysine analog.

[Conjugation in Rhodopseudomonas sphaeroides mediated by R plasmids]. / Kon"iugatsiia u Rhodopseudomonas sphaeroides, obuslovlennaia R-plazmidami.

Plasmids R68.45, RP4, RP4::Mu cts62, RP1ts::Tn10, RP1ts::Tn9, Rts1 and RP41 were transferred into cells of photosynthetic nitrogen-fixation bacterium Rhodopseudomonas sphaeroides from Escherichia coli and Pseudomonas aeruginosa. The transfer of plasmids occurred with high frequency of 10(-1) to 10(-2) per donor cell in all cases. Mobilization of R. sphaeroides 2R chromosome was obtained by RP4 and Rts1 plasmids at a frequency of 10(-7) to 10(-8) per donor cell in all cases. Mobilization of R. sphaeroides 2R chromosome was obtained by RP4 and Rts1 plasmids at a frequency of 10(-7) to 10(-8) per donor cell. Bacteriophage Mu cts62 could be induced from the plasmid DNA in R. sphaeroides 2R cells and was capable of the lytic growth and producing phage progeny. It was demonstrated that an increase in the efficiency of donor chromosomal genes transfer into recipient cells could be achieved in crosses with the donor carrying RP4::Mcts62 plasmid.