Том 55, № 1 (2019)

The review addresses various aspects of the interaction between carbon nanotubes (CNTs) and microorganisms: the antimicrobial effects of single-walled, multiwalled, functionalized, and nonfunctionalized CNTs; the mechanism of action of these nanomaterials at the single-cell level; and their effects on soil and aquatic microorganisms. Among the mechanisms of action of CNTs on the microbial cell, one should note direct contact, which leads to disruption of the cell wall and cytoplasmic membrane, changes in membrane fluidity, oxidative stress, enzyme inhibition, and reduced transcription of several key genes. It has been shown that the antimicrobial effect of CNTs strongly depends on their diameter, length, aggregation degree, concentration, surface functionalization, degree of purification, and time and intensity of contact. The possibilities of the CNT biodegradation by microorganisms have been studied. It has been shown that the introduction of nanotubes into soils results in changes in the abundances of bacteria of certain taxonomic groups involved in biogeochemical cycles of carbon and nitrogen. This may adversely affect the cycling of these elements in the nature. The review also focuses on recent trends in the development of microbial fuel cells, biosensor technologies, bioremediation, and wastewater treatment in which CNTs display their unique electron-conducting and adsorption properties and serve as a bridge for an understanding of the beneficial aspects of microorganisms.

A method to increase the thromboresistance of the biospecific antiproteinase hemosorbent was suggested based on simultaneous immobilization of duck egg ovomucoid and blood anticoagulant—heparin or hirudin—in the bulk of polyacrylamide hydrogel. It was demonstrated that modification of the hemosorbent with hirudin resulted in a significant increase of its compatibility with blood with simultaneous preservation of high capacity with regards to serine proteinases.

Polyaniline/carboxylated multiwalled carbon-nanotube composites were synthesized with the use of laccase from the fungus Trametes hirsuta as a catalyst of aniline oxidative polymerization. Atmospheric oxygen was an oxidant. Aniline dimer adsorbed on the carbon material surface served as an enhancer of the enzymatic polymerization of aniline. The composites were synthesized in deionized water without any acidic dopant. The structure, morphology, and electrochemical characteristics of the obtained nanocomposite were examined. It has been shown that the carboxylic groups on the surface of multiwalled carbon nanotubes result in the electrochemical activity of polyaniline in solutions with a neutral pH.

It has been found that the bacteria Bacillus subtilis Cohn. (strain 26 D) and Bacillus thuringiensis Berliner (strains V-6066 and V-5689) are able to suppress the vital activity of the greenbug aphid Schizaphis graminum Rond. The protective effects of the studied Bacillus spp. strains consisted of direct aphicidal activity, and they indirectly induce systemic resistance in wheat plants via the regulation of hydrogen peroxide generation, the activity of peroxidase and catalase, and an increased expression of defense-related genes, such us NADPH oxidases, PR-6, and PR-9. It has been shown that B. thuringiensis strains induced genes of the jasmonate-dependent signaling pathway, and B. subtilis strain induced genes of the salicylate-dependent signaling pathway. It has been found that the composition of the studied Bacillus spp. strains had an additive effect of wheat plant resistance to pests. These results support the use of these Bacillus spp. strains as a basis for the further development of a biopreparation against cereal aphids.

An association of low molecular weight, light-inducible HliA/HliA stress proteins with thylakoid chlorophyll–protein complexes of the cyanobacterium Synechocystis sp. PCC 6803 was studied. It is shown via two-dimensional electrophoresis in PAAG, mass spectrometry, and Western blotting that these light-inducible HliA/HliB stress proteins are associated with monomers and trimeric photosystem I (PSI) сomplexes and the photosystem II (PSII) complex. This suggests that these proteins play a universal role in the protection of the photosynthetic apparatus from excess light. To evaluate the functions of Hli proteins and their effect on the photochemical activity of PSI, non-HliA/HliB cells were compared with cyanobacterial cells containing these proteins. It is shown that the PSI photochemical activity was three to four times lower in the absence of HliA/HliB proteins than in the presence of Hli proteins. This suggests that Hli proteins are important for the reaction to oxygen consumption in PSI with an artificial donor and acceptor, which indicates their role in the maintenance of optimal PSI activity.

Inhibition of the autoxidation of polyunsaturated fatty acid methyl esters isolated from fish oil by essential oils of clove, oregano and their mixture has been studied. Their content was determined after 1–6 months of autoxidation by capillary gas chromatography to assess antioxidant efficiency. It has been shown that the essential oils of clove and oregano and their combination effectively inhibited the autoxidation of polyunsaturated fatty acids. The degree of this inhibition depended on the structure of fatty acids and the composition of their mixtures, as well as on the essential oil content and duration of autoxidation. It was shown that an increase in the number of double bonds in unsaturated acid molecules resulted in a decreased resistance of their esters to oxidation. In the control, 97% of monounsaturated acids and only 9% of docosahexaenoic acid remained after 3 months of autoxidation. Clove essential oils at concentrations of 2 and 4% inhibited oxidation with equal efficiency; after 3 months, 86–91% of esters of acids with five and six double bonds remained. Oregano essential oil was less effective as an antioxidant than the clove. Thus, up to 79% of methyl eicosapentaenoate and 73% of methyl docosahexaenoate remained after 3 months of autoxidation in its presence. After 6 months of autoxidation, the methyl eicosapentaenoate and docosahexaenoate contents were 67 and 54% in the presence of 4% clove oil and only 11 and 7%, respectively, with 1% oil. The inhibitory activity of 4% oregano oil and 2% clove oil turned out to be almost the same, and a similar content of all unoxidized acids was observed in the presence of 1% oils. A mixture of clove and oregano essential oils showed an additive antioxidant effect on arachidonic and eicosapentaenoic acids esters and a synergistic effect on docosahexaenoic acid ester.

Surface-enhanced Raman spectroscopy (SERS) is a prospective method for the detection and identification of microorganisms. Hereby we describe the method for the registration of bacterial SERS spectra, including the mild oxidation sample treatment for the additional amplification of SERS signal. We also propose the spectral data processing method for the calculation of distinguishing criteria for the bacterial spectra.