Vol 59, No 2 (2023)

Extracellular vesicles, secreted by bacterial cells, are the focus of close attention of researchers. They are enriched with bioactive molecules, mediate the intercellular communication of micro- and macroorganisms, participate in the adaptation of bacteria to stressful conditions, reprogramming target cells, modulating immunoreactivity in higher organisms, changing the structure of microbial communities and ecosystems. The unique properties of bacterial extracellular vesicles (BEVs) open up broad prospects for their practical application – in clinical medicine, agriculture, biotechnology and ecology as diagnostic markers, vaccines, new biological products and means of their delivery. However, to implement the practical applications, a number of problems need to be solved. This review focuses on the ambiguous role of BEVs in the regulation of living systems, the problem of assessing the safety of BEVs and approaches to its solution related to innovative technologies.

Pollution of the environment with heavy metals, metalloids and radionuclides is a global problem that seriously affects the state of the biosphere. In particular, chromium compounds have a toxic, mutagenic and carcinogenic effect. The main principle of purification of anthropogenic and natural ecosystems from chromates is the reduction of Cr(VI) to Cr(III), the salts of which are significantly less toxic and insoluble. However, currently used electrochemical and ion-exchange cleaning methods are quite expensive and require the use of special reagents. At the same time, sulfate-reducing bacteria (SRB) are of particular interest for bioremediation of this kind, since many of them are very resistant to high concentrations of heavy metals and are able to effectively reduce them in the presence of hydrogen as an electron donor. The review summarizes known data on the interaction of heavy metals, metalloids and radionuclides with SRB. The features of the metabolism of these microorganisms, leading to intracellular accumulation of heavy metals and metalloids, are considered. Complex and finely regulated enzymatic mechanisms for the reduction of toxic metals (using various cytochromes, hydrogenases, oxidoreductases, highly specific metal reductases, and thioredoxin/thioredoxin-reductase systems), as well as the possibility of using immobilized cells and biofilms of SRB in the effective bioremediation of natural waters, soils, and industrial effluents, are described.

A recombinant strain producing human gamma interferon (IFN-γ) E. coli BL 21/pET-IFN-γ was constructed, providing a high level of its expression. A method has been developed for obtaining a soluble form of recombinant IFN-γ, consisting of the processes of producing a biomass of a producer strain containing a target protein in an amount of 32–37% of the total content of cellular proteins, protein isolation and purification. The purification process included the stages of disintegration, clarification of the cell lysate, chromatographic purification and dialysis. The developed method makes it possible to obtain from 1 g of wet biomass up to 5 mg of the drug with a purity of at least 95% and high specific (antiviral) activity.

The interaction of endoarabinase (endoA) with exo-type enzymes was studied during their joint hydrolysis of branched arabinane (BAra), sugar beet pulp (SBP) and apple pomace (AP). It was shown that mixtures of endoA with arabinofuranosidase (AF) or arabinoxylan-arabinofuranhydrolase (AXH) with endoA content of 20 and 40%, respectively, were the most effective in the hydrolysis of BAra. As a result of the optimization of the complex of arabinases, cellulases and pectinase, almost complete conversion of AP into monosaccharides (arabinose, glucose, fructose) was carried out. During the hydrolysis of SBP, the conversion rate of hemicellulose (arabinane) was more than 50%, cellulose – 75%.

Changes in the concentrations of hydrogen peroxide and cyclic adenosine monophosphate (cAMP) in the roots of seedlings of pea cv. Rondo and its supernodulating mutant Nod3 and anodulating K14 were studied during infection with Rhizobium leguminosarum bv. vicea (strain RCAM 1022) or Pseudomonas syringae pv. pisi (strain 1845). It was shown that 360 min after infection of pea seedlings of the Rondo variety, the level of endogenous hydrogen peroxide slightly differed from the control. In the roots of Nod3 seedlings, this level significantly decreased, and in the roots of K14 it significantly increased when infected with the 1845 strain, but remained unchanged when exposed to bacteria of the RCAM 1022 strain. and young root hairs of Rondo seedlings, while strain 1845 had no effect on this parameter. Both types of bacteria had no effect on the concentration of cAMP in the roots of seedlings of the Nod3 mutant, whereas in K14, under the influence of RCAM 1022, the cAMP level almost doubled, and under the influence of 1845, it decreased. It is assumed that hydrogen peroxide and cAMP may be involved in the formation of supernodulating and nodulating phenotypes of mutants, as well as in the formation of resistance to a specific pathogen, Pseudomonas syringae pv. pisi. It is possible that this phenomenon can be used to diagnose the resistance of newly created mutants and pea varieties to the blight pathogen.