[Genetic control of the destruction of surface-active agents]. / Geneticheskii kontrol' destruktsii poverkhnostno-aktivnykh veshchestv.

Degradation of anionic, cationic, and zwitterionic surfactants, such as alkylbenzene sulfonate, ethonium, amidobetaine, and alkylaminobispropionate, by pseudomonads can be controlled by plasmid genes. The majority of plasmids of surfactant-degrading strains are capable of conjugal transfer.

[Plasmid determined degradation of sulfo-aromatic compounds by Pseudomonas sp. BS1304]. / Plazmidnyi kontrol' degradatsii sul'foaromaticheskikh soedinenii shtammom Pseudomonas sp. DS1304.

Utilized sulfo-aromatic compounds of Pseudomonas sp. BS1304 were isolated. It was shown that the first step of conversion is desulfonation with following meta-cleavage of the substituted aromatic ring. At least two steps are controlled by the plasmid pBS1004 (120 kb), belonging to the IncP-9 incompatibility group. The degradative plasmid marked by Tn5-lac may be mobilized to P. putida, P. aeruginosa, P. mendocina, where a degradative phenotype is expressed.

[Preparation and analysis of mutants of rhizospheric pseudomonads, resistant to toxic analogs of tryptophan and phenylalanine]. / Poluchenie i analiz mutantov rizosfernykh psevdomonad, ustoichivykh k toksichnym analogam triptofana i fenilalanina.

The absence of plasmids in strains of fluorescent pseudomonads characterized by high level of synthesis of phytohormone indole-3-acetic acid (IAA) as well as invariability of this feature in plasmid and non-plasmid variants of strain BSP8 suggests chromosomal control of IAA synthesis by the rhizosphere bacteria tested. Using toxic analogues of aromatic amino acids -5-fluorine-tryptophan and 5-methyl-tryptophan variants were obtained which synthesized and secreted only anthranilic acid. Mutants with resistance to p-fluorine-phenylalanine and capable of secreting tryptophan and/or phenylalanine were found. Testing of the secreting variants failed to reveal any differences between the levels of IAA biosynthesis in comparison with the wild-type strains.

[Analysis of the conjugation system of plasmid pBS1001 with a broad range of hosts]. / Analiz kon''iugationnoi sistemy plazmidy s shirokim krugom khoziaev pBS1001.

Tn5-induced tra mutations were localized on the physical map of a broad host range plasmid pBS1001. Mutations were united into three clusters covering 25% of plasmid DNA. They were distributed in 7 groups by complementation analysis. It was shown that coexistence of tra mutants of pBS1001 and RP4 within the same cell did not restore conjugation properties of both plasmids. High frequency mobilization of some known vectors by pBS1001 was demonstrated.

[Localization in Escherichia coli of transcribed regions of the broad host range plasmid pBS222]. / Lokalizatsiia transkribiruemykh v Escherichia coli oblastei plazmidy pBS222 s shirokim krugom khoziaev.

The set of insertions of the CmR-gene region devoid of the promoter into the broad host-range plasmid pBS222 regions transcribed in Escherichia coli cells has been obtained and characterized. Three transcribed regions of the plasmid that are dispensable for life functions of the plasmid have been identified by the insertions technique. The deleted plasmid derivatives have been isolated suitable for using as the broad host-range vectors.

[A new plasmid pBS1001 with broad range of hosts]. / Novaia plazmida s shirokim krugom khoziaev pBS1001.

A new broad host-range plasmid capable of conjugative transfer has been isolated and characterized. The plasmid has the high frequency of conjugation transfer, is capable of conjugative transfer mobilization of nonconjugative plasmids, carries no known phenotypic markers. The plasmid demonstrates the specific interaction with the plasmids of P incompatibility group. The comparatively small size of the plasmid permits one to use it efficiently for comparative study of organization of the broad host range plasmids.

[Transposition of insertional sequence IS21 in E. coli cells activated by an exogenous promotor]. / Aktiviruemaia vneshnim promotorom transpozitsiia insertsionnoi posledovatel'nosti IS21 v kletkakh E. coli.

Transpositional activity of the IS21-element was found to be activated during its cloning in the pUC18 vector plasmid. The activated IS-element restores ability to transposition of the deficient IS21-element present in the same cell. Simultaneously with the activated transposition the increase in frequencies of precise exclusion of IS-element is registered. The activation of IS-element is concluded to be directed by exogenous promoter.

[Directed mutagenesis of chromosomal genes of Escherichia coli in vivo: construction of RecA- and HtpR- mutants]. / Napravlennyi mutagenez khromosomnykh genov Escherichia coli in vivo: konstruirovanie RecA- i HtpR- mutantov.

The deletions in Escherichia coli chromosomal genes recA and htpR were constructed using the site-directed mutagenesis techniques. The obtained RecA- mutants are UV-sensitive and have a phenotype defective for the homologous DNA recombination. HtpR- mutant is temperature sensitive for growth and deficient in intracellular proteolysis. As a result a HtpR- mutant seems to be a preferable candidate for attempting to synthesize efficiently any alien protein in Escherichia coli cells.

[Mobilization of the pACYC184 plasmid by hybrid pAS8-121 delta plasmids in Escherichia coli cells]. / Mobilizatsiia plazmidy pACYC184 gibridnymi plazmidami pAS8-121 delta v kletkakh Escherichia coli.

The plasmid pACYC184 is shown to be mobilized for conjugal transfer in Escherichia coli cells by the deleted (Tn7-TcR) derivatives of the hybrid conjugative plasmid pAS8-121 (RP4-Co1E1). Both the mobilized and mobilizing plasmids are autonomously inherited by the recipient cells when the mobilizing plasmid carries single copy of IS8 (the plasmid pAS8-121 delta 16). Cointegrates pAS8-121 delta 16D:: ::pACYC184 are found in the recipient cells with pACYC184 being inserted between two repeats of IS8 if the derivate plasmid pAS8-121 delta 16D having the duplication of IS8 is used to mobilize pACYC184 for conjugal transfer. The insertion of pACYC184 between IS8 repeats in the plasmid pAS8-121 delta 16D eliminates the plasmid ability to be inserted with high frequency into the chromosome of the phototrophic bacterium R. sphaeroides 2R. The cointegrate pAS8-121 delta 16D:: pACYC184 is stable but can be resolved during the transformation deriving the plasmid pACYC184:: IS8. The latter may be used as a probe for isolation and analysis of IS8 DNA sequences and for constructing the vectors on the basis of pACYC184.

[Variants of the plasmid pAS8 delta with increased frequency of integration into Rhodopseudomonas sphaeroides chromosome--the result of IS8-element duplication]. / Varianty plazmidy pAS8-121 delta s povyshennoi chastotoi integratsiiv khromosomu Rhodopseudomonas sphaeroides--rezul'tat duplikatsii IS8-élementa.

The possible participation of IS8 and IS elements of Rhodopseudomonas sphaeroides in cointegrate formation by chromosome of the purple bacterium and plasmid pAS8-121 delta has been studied. The plasmid derivatives having deleted Tn7 have been studied. Plasmid integration into the chromosome of the purple bacterium is shown to be mediated by IS8 element of the plasmid. Plasmid derivatives having the integration potential increased for two orders were isolated by a series of intergeneric conjugational crosses during which plasmid pAS8-121 delta was transferred from Rhodopseudomonas sphaeroides (cointegrate of plasmid and chromosome) to Escherichia coli (plasmid in an autonomous state) and back to Rhodopseudomonas sphaeroides. The restriction analysis of plasmid DNA digested by Hpal and Smal restriction endonucleases has revealed the tandem duplications of IS8 in plasmids capable of integration into the chromosome of the purple bacterium with a high frequency.

[Inheritance of hybrid plasmid pAS*-21 by cells of the purple phototropic nitrogen-fixing bacterium Rhodopseudomonas sphaeroides]. / Nasledovanie gibridnoi plazmidy pAS8-21 kletkami purpurnoi fototropnoi azotfiksiruiushchei bakterii Rhodopseudomonas sphaeroides.

Clones of purple nitrogenfixing prototrophic bacterium Rhodopseudomonas sphaeroides carrying an incertion into the chromosome of the hybrid pAS8-121 (RP4-ColE1 (repA::Tn7] plasmid were analysed. It is revealed that plasmid integration could be due to both Tn7 and other migrating elements (IS8 and possibly, to resident migrating elements of purple bacteria). The plasmid pAS 8-121 can be autonomously transferred from the cointegrate state into Escherichia coli K-12; the plasmid is not inherited autonomously in cells of the purple bacterium. In E. coli cells R' derivatives of the plasmid carrying R. sphaeroides chromosomal fragments may be formed. The R' plasmids with fragments of plasmid DNA substituted for chromosomal material of R. sphaeroides were selected in E. coli K-12 cells among deleted (Kms) derivatives of pAS8-121.