Том 52, № 8 (2016)

The results of a study on the immunobiological properties of a new, naturally attenuated, unencapsulated Bacillus anthracis 363/11 strain in comparison with the properties of the anthrax vaccine strain 55-VNIIVVIM, which is currently used in Russia and post-Soviet states, are presented in the article. Some differences in the phenotypes of the aforementioned strains are shown. The new strain caused lysis of sheep erythrocytes by α- but not by β-type; the strain had many more active proteinases and synthesized protocatechuic acid (PCA), in contrast to the vaccine strain. It was ascertained that immunization of animals by the new strain protects them from death after infection by field isolates of B. anthracis, while the 55-VNIIVVIM strain does not create this immunity. The data indicate that the new strain can be used to develop and improve anthrax prevention.

The influence of population heterogeneity and medium pH factors on the effect of α-acetolactate (AL) overproduction that we found in L. lactis bv. diacetylactis B2103/74 culture was studied. The nature of the enzymatic system responsible for this effect (which is able to considerably block lactate dehydrogenase (LDH) by intercepting up to 80% of the NADH in it) is unknown; we designated this system as the heminindependent electron transferring system (HEMIETS). It was demonstrated that manifestation of the effect was masked by the culture heterogeneity and was especially strong in approximately neutral pH values (6.1–6.5). The presence in the population of at least three types of dissociants differing in the level of HEMIETS activity, and consequently AL synthesis, was established: an active dissociant (AL accumulation up to 30 mM), an inactive dissociant that had lost the HEMIETS (AL no more than 3 mM), and a dissociant with intermediate activity (AL 15–17 mM). It was demonstrated that the HEMIETS activity at a particular pH value had primary importance in the emerging general picture of pyruvate metabolism at different pH values and, finally, in overproduction. Thus, no overproduction effect was observed at a pH of 7.0 due to the low HEMIETS activity, and the pyruvate metabolism passed according to homolactic type. However, the HEMIETS activity was so high at pH values of 5.3–6.5 that this allowed it to take the function of the main regulator of NAD⁺/NADH oxidation–reduction balance and to give a minor role to LDH. The LDH- and acetolactate synthase pathway productivity depended on the HEMIETS activity at a particular pH, while the productivity of pyruvate dehydrogenase pathway directly depended on the external pH. The latter was relatively high in approximately neutral area (pH 6.0–6.5) and was noticeably decreased in neutral (pH 7.0) and weakly acid (pH ≤ 6.0) zones.

Silver sulfide nanoparticles stable in aqueous solutions were obtained in presence of the cells of the bacterium Shewanella oneidensis MR-1 in aqueous solution containing an equimolar mixture of AgNO₃ and Na₂S₂O₃. Proteins absorbed on the surface of Ag₂S nanoparticles were identified for the first time by MALDITOF/TOF. Among these proteins, multiheme cytochromes MtrC and OmcA, as well as the MtrB membrane porin, which forms a complex on the outer cell membrane, were detected. It was shown that an insoluble precipitate consisting of agglomerated Ag₂S nanoparticles with a wide size distribution was formed in the absence of the cells. The role of the detected proteins in the mechanism of the formation and stabilization of the Ag₂S nanoparticles in the studied system is discussed.