[Comparative study of the diagnostic value of new cholera eltor bacteriophages ctx+, ctx-, and KhDF-3, 4, and 5].

The comparative evaluation of the diagnostic value of new cholera eltor bacteriophages ctx+ and ctx-, as well as monophages X[symbol: see text]-3, 4, 5, demonstrated their high activity and specificity. Using of these bacteriophages epidemic potential of 95% Vibrio cholerae eltor strains ctx+ and 84.5% of V.

[Phenotypic analysis of two morphologically different types of Vibrio cholerae 0139 colonies].

A clinical isolate Vibrio cholerae P16064 serogroup 0139 was shown to produce two different kinds of colonies: opaque encapsulated and translucent devoid of capsule. Low virulence of translucent colonies seems to be due to not only loss of capsule which determines serum resistance, but also to decreased expression of genes controlling the motility, and production of protease and mannose-sensitive adhesion pili. Analysis of the lysogenic properties of the two types of colonies permitted us to propose that simultaneous spontaneous alteration of capsule production and the above-mentioned virulence factors in translucent colonies may be caused by a temperate phage in turbid clones of strain P16064.

[Cloning, structure and expression of the full-size lon gene in Escherichia coli coding for ATP-dependent La-proteinase].

Assembly of the full Escherichia coli K-12 lon gene from the EcoRI--SphI fragment of the bacterial DNA ("modified" gene) cloned and sequenced earlier and the PstI fragment of the same DNA containing 3'-terminal region of the lon gene has been performed. Both "modified" and full genes showed all phenotype properties of lon gene. The complete nucleotide sequence of the gene (2770 bp) coding for the 784 amino acid sequence of protease La was determined.

[Cloning, expression and structure of the functionally active shortened lon gene in Escherichia coli].

Lon gene of E. coli has been cloned into the plasmid pBR327. Full nucleotide sequence of the gene has been established.