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A dynamic approach was employed for a study of the reaction of the fatty acid pool of sensitive and resistant strains of E. coli K12 in response to the introduction of antibiotics. Bacteria whose resistance is controlled by plasmids exhibited a specific reaction - a reversible increase in the concentration of cis-9,10-methyl-enehexadecanoic acid. Strains of E. coli K12 (C600, J53, CSH-2) carrying plasmids RP4, R6K, R1 drd 19, pMB9, R386, RP1, RtS-1, were studied.

Experiments on E. coli used as a model have revealed that fatty-acid composition is one of the characteristics which determine the viability of bacteria in the air. The viability of microbial cells in the air has been shown to increase with the increase of the pool of cyclopropane acids and the palmitic acid/palmitoleic acid ratio in the cells, irrespective of their genotype and the phase of their growth.

The fatty acid composition of twelve Bdellovibrio strains isolated upon the growth on bacteria of various taxonomic groups was studied. A dependence of the lipid composition of bdellovibrios on that of bacteria they were parasitizing on was shown. Data pointing to the selective incorporation of fatty acids of host bacteria by bdellovibrios were obtained. Bdellovibrio membranes were shown to contain monounsatured fatty acids with different positions of double bonds indicating that there are at least two alternative mechanisms of synthesis of these acids in the parasites.

Fatty acid composition of the cells of Escherchia coli wild strains K-10, and K-12 and the mutants of the regulatory genes for alkaline phosphatase was studied in conditions of repression and derepression of biosynthesis of phosphohydrolases. Derepression of phosphohydrolases was not accompanied with specific changes in fatty acid composition of the cells. An increase in the content of cyclopropanic acid in conditions of phosphorus deficiency and a decrease in the level of unsaturated fatty acids are related to deceleration of growth of the cells in these conditions.

The bactericidal effect of water from the Indian and Pacific oceans and Caspian and White seas on Escherichia coli was studied. It is shown that a decrease in the viability of E. coli cells is accompanied by the appearance and active multiplication of small bacteria of a vibrioid form. Two strains of such bacteria were isolated from a suspension of E. coli in seawater and purified from membranes of the substrate organism by the method of centrifugation in a Ficoll gradient. The marine bacteria of vibrioid form are very similar to the bacterial parasite Bdellovibrio bacteriovorus in fatty acid composition and characteristic cycle of development.

A new species of exoparasitic bacteria, Micavibrio aeruginosavorus sp. nov., was isolated on the host bacterium, Pseudomonas aeruginosa. Its diagnosis is given.

Gas chromatography is used to determine the specificity of microbial esterases in vivo. The technique is based on hydrolysis by the cells of esters of fatty acids containing different alcohol groups. The specificity was evaluated by means of the coefficient Kc which changed from 0 to 1 and did not depend on the time of hydrolysis. The esterases of M lysodeicticus were more specific than the esterases of S. marcescens by a factor of 30 during hydrolysis of the equimolar mixture of methyl ester of pelargonic acid and ethyl ester of caprylic acid. This criterium of specificity may be used for rapid identification of bacteria.

By-products of the transformation were studied, which were formed in the process of 11alpha and 11beta-hydroxylation of 21-acetate of the Reichstein substance "S" by the culture of Tieghemella orchidis. The following steroid derivatives, known before, were isolated: epihydrocortisone, 6beta-hydroxy derivative of the Reichstein substance "S", hydrocortisone, cortisone. The following steroid derivatives were isolated from the initial chloroform extract of the fermentation medium, and identified: prednisolone, androstendione, testololactone, and 1,2-dehydro derivatives of the Reichstein substance S" and its 21-acetate. The quantitative ratio between the products of transformation depended on the conditions of growth and transformation. These compounds seem to be intermediate metabolites in the course of the steroid destruction via the pathway common for fungi and involving the destruction of D ring of the steroid molecule.

A destructive chromatographic method of identifying microorganisms is described. The method is based on hydrolysis of the biomass of the microorganisms in the presence of tetramethylammonium hydroxide, followed by introduction of the hydrolyzate into the heated injector of a gas chromatograph. The main products in this case are methyl esters of fatty acids, the composition of which is used as a diagnostic criterion. Chromatograms of the residues after chloroform-methanol extraction and the dynamics of the change in total fatty acids in the process of growth can also be used for identification. The dynamics of total fatty acids was studied in E. coli strain K-12, and destructive chromatograms for bacteria and yeasts are cited.