卷 93, 编号 2 (2024)

Although thermokarst alas lakes of Central Yakutia are of great climatic and economic importance, there is currently virtually no information on microbial communities and microbial processes in these lakes. This paper characterizes the hydrochemical features and presents a primary analysis of the diversity of planktonic microbial communities in three alas lakes of Central Yakutia — Tyungulyu, Taby, and Kharyyalakh. It was shown that in terms of the water physicochemical composition, the studied lakes were quite typical for this region; they had increased alkalinity and trophicity, but differed from each other in microbiological indicators. Chemoheterotrophic prokaryotes predominated in the studied planktonic communities, but a significant proportion of the 16S rRNA gene sequences were most similar to uncultured microorganisms whose functional potential is still unknown.

A plasmid containing the genes of a fungal 17β-hydroxysteroid dehydrogenase, which catalyzes the reduction of the steroid core at the C17 position, and mycobacterial glucose-6-phosphate dehydrogenase, which promotes the recycling of the essential coenzyme NAD(P)H, was constructed. Its constitutive expression in well-studied Mycolicibacterium neoaurum strains made it possible to increase significantly the yield of C-17 hydroxysteroids. In particular, recombinant strains created on the basis of M. neoaurum VKM Ac-1815D and M. neoaurum NRRL B-3805 ΔkstD exhibited predominant accumulation of testosterone, while the strain based on M. neoaurum VKM Ac-1816D accumulated dehydrotestosterone and testosterone simultaneously.

Molecular biological techniques and bioinformatic analysis were used to investigate the phylogenetic and functional diversity of the prokaryotic complex of soil microcosms. The dominant organisms of the hydrolytic community were different in the samples from different climatic zones. In the soils subject to anthropogenic or abiogenic load, apart from decreased diversity and abundance of prokaryotes, the number of the genes marking the ability to degrade xenobiotics, as well as those encoding nitrogen conversion and metabolism of vitamins and cofactors, was found to increase. Under heavy oil contamination, the bacterial community was capable of nitrification; its role increased in the lower horizons of the soil profile. The patterns revealed in the work indicate high metabolic potential of the prokaryotic component of the studied soils.

New vectors for the yeast genome editing using CRISPR/Cas9 were constructed. A system for cloning of new targets using the standard methods (PCR‒restriction‒ligation) was developed and successfully applied. The constructed vectors allowed us to obtain the sup35-25 mutants, deletion of the PSH1 gene and disruption of the NAM7 (UPF1). A convenient method for identifying plasmids with a new target was tested. A detailed description of the cloning technique used and selection of plasmids with the new targets is provided.

A new haloalkaliphilic member of the genus Salisediminibacterium (family Bacillaceae) with high chromate-reducing activity in a broad range of conditions was isolated. Reduction efficiency after 3 days was up to 99% at initial Cr(VI) concentrations 15 and 100 mg/L for mineral and organic media, respectively. Effect of organic matter on the rate of chromate reduction was shown. The isolate MB1000 differed from the presently described members of the genus Salisediminibacterium in its physiological characteristics.

The bacterioplankton of Lake Khubsugl (Hövsgöl) has significant differences from that of large ancient and oligotrophic water bodies. The greatest similarity was noted, however, between the microbiomes of Lake Khubsugul and Lake Baikal, the lakes located in the same rift zone and connected by the river system, which emphasizes the similarity of microbiomes at the regional level. In the global aspect, geographical zonation had the greatest reliable significance in the microbial community biogeography, while depth had the lowest. Trophic status of the lakes, as well as their ancient origin, did not affect the clustering of microbiomes, with the seasonal factor playing the major part at the local and regional levels.

This is the first report on microbial communities associated with the freshwater snail Kamtschaticana kamtschatica inhabiting diverse types of water basins in Eastern Siberia and the Russian Far East. Using metabarcoding data based on the 16S rRNA gene fragments, taxonomic profiling of bacterial communities associated with snails from three basins of the Magadan Oblast was carried out. Predominant phyla in the studied bacterial communities were Pseudomonadota, Bacillota, Cyanobacteriota, Actinomycetota, Verrucomicrobiota, Planctomycetota, and Bacteroidota. The highest alpha-diversity, according to the Chao1 index, was revealed in the mollusks from the Orotukan reservoir. The relative abundance of bacteria of the genera Snowella, Leptolyngbya, Nodosilinea, Arenimonas, and Polaromonas significantly distinguished the mollusks of this habitat from those of the other two. The greatest similarities in the composition of the microbiota in K. kamtschatica were found for the genus Pseudomonas, which was present in the majority of samples in the amount of more than 1% and was not found in the sediment samples. Obtained data on the diversity and composition of bacterial communities associated with lymnaeid snails are of fundamental importance for the ecology of freshwater mollusks.

Conservative motifs (peptide patterns) determining the elicitor properties of plant-pathogenic bacteria were revealed in amino acid sequences of the flagellins of phytopathogenic, associated, and root nodule microflora. In plant growth-promoting rhizobacteria (PGPR), analogs of one (flg22) out of two (flg22 and flgII-28) specific peptides, characterizing pathogens were revealed. Instead of glycine G18, characteristic of an elicitor, tyrosine Y18 was identified in flg22 analogs of most PGPR, which prevents actuation of the phytoimmunity mechanism against PGPR. Molecular docking with the AlphaFold software complex demonstrated reliability of the interaction between the plant receptor FLS2 and the canonical peptide flg22 and its analogs from a plant pathogen and an Azospirillum. However, in the case of the FLS3 plant receptor only its interactions with the canonical peptide flgII-28 and its analog from the plant pathogen were reliable.

Bacterial PII-like proteins are global regulators of nitrogen and energy metabolism, which respond to nutrient availability by binding their partner proteins, thus modulating their activity. The PotN protein from Lentilactobacillus hilgardii, a member of the new family of PII-like proteins, is capable of competitive binding of ATP and ADP, thus regulating metabolism in response to the cell energy status. Thus, under ADP excess, PotN binds this nucleotide and interacts mostly with the PotA subunit of the polyamine АВС transporter, suppressing its ATPase activity. PotN also dissociates from the transcription factor GlnR, restoring its ability to bind DNA and modulate expression of the genes of the GlnR regulon. On the contrary, in the ATP state PotN dissociates from PotA and binds to the GlnR factor.

The effect of waste treatment plants in Pushchino, Russia on abundance of antibiotic-resistant microorganisms and determinants of multiple drug resistance in the Oka River water and sediments was investigated. Treated wastewater was found to contribute to contamination of the Oka surface water layer with aminoglycoside-resistant strains. The role of Pushchino waste treatment plants in the dissemination of multidrug-resistant strains and plasmids of the А/С incompatibility groups (IncA/C) was demonstrated. Waste treatment plants were shown to affect both the total abundance of eubacteria in sediments and to assect their composition, increasing the relative abundance of pseudomonads.

The work deals with investigation of genetic diversity and biogeography of T4-like cyanophages from the shallow bay of the Posolsk Sor (Lake Baikal), based on analysis of the g20 marker gene. High diversity of g20 gene fragments and their uniqueness were revealed. The greatest similarity was noted with the previously obtained sequences from Lake Baikal and with those from freshwater ecosystems: oligotrophic Lake Green, Lake Round, oligomesotrophic Lake Ancy, and mesotrophic Lake Bourget. From the point of view of biogeography, it was determined that the phage sequences were similar to the previously obtained ones from different Lake Baikal ecotopes than to those from other ecosystems.

Phosphorus is one of the major biogenic elements. Its inflow facilitates eutrophication of lake water. In aquatic ecosystems, phosphorus is present mostly in organic compounds. Ability of aquatic microorganisms to assimilate phosphorus from organophosphorous compounds results from activity of alkaline phosphatases; activity of these enzymes may be an indicator of the state of the ecosystem, phosphate load, and water quality. In the present work, alkaline phosphatase activity (APA) and abundance of phosphatase-active bacteria (PAB) in Lake Baikal pelagic zone and in the mouths of its major tributaries was studied. In the pelagic zone, APA and PAB abundance decreased with depth, indicating that the main processes of phosphate generation occurred in the trophic layer of the lake. In the main tributaries, both APA and PAB abundance were considerably higher than in the pelagic zone. These results indicate active biochemical processes of transformation of organophosphorous compounds occur in the estuarine zones of the rivers. The degradation processes result in regeneration of phosphates, which are completely incorporated in the biological turnover, providing for phytoplankton development.

Resistance of polymer composite materials to biodamage is one of the pressing problems of our time. Incorporation of Cu₂O (I) in the composition of a polymer composite based on the ED-20 epoxy resin increases its biocidal properties. Under conditions of mineral and organic contamination, the area of the samples affected by micromycetes was found to decrease with increasing concentration of dispersed particles in the composite. The affected area of the samples filled with the particles encapsulated in polylactide was 1.5 times smaller than that of the composites filled with non-encapsulated particles. Сopper oxide had a toxic effect on the Aspergillus niger strain dominant on the surface of the samples, causing a decrease in the average radial growth rate on the Czapek-Dox agar medium and in the biomass weight concentration during the growth of micromycetes in a liquid medium compared to the variant without Cu₂O.

A total of 397 Mycobacterium tuberculosis strains isolated from newly diagnosed patients with pulmonary tuberculosis in the Omsk region in 2019‒2020 were genotyped. The prevalence of strains of the Beijing genotype (70.8%) was established, in particular of two clusters of the modern sublineage — Central Asian/Russian (46.1%) and B0/W148 (19.1%). Strains of the ancient sublineage of the Beijing genotype were represented by clusters 1071-32 and 14717-15, totaling 4.8%. Compared with other genotypes, B0/W148 cluster and the ancient Beijing sublineage were associated with multidrug resistance (MDR): 93.4% and 94.7%, respectively (P < 0.0001). Among representatives of other genetic families (LAM, Ural, T, Haarlem), drug-sensitive strains predominated (75.0%). The circulation of MDR Beijing strains requires molecular epidemiological surveillance in view of their possible wider spread.