Microbiology

Precipitation of authigenic carbonates during diagenesis of bottom sediments is often a by-product of microbial activity, and the isotopic characteristics of such carbonate minerals are determined by the effects of carbon isotope fractionation during enzymatic reactions. The composition of microbial communities was estimated using the 16S rRNA gene metabarcoding method, and the chemical composition of pore waters of bottom sediments of three mud volcanoes of Lake Baikal containing siderites (FeCO₃) anomalously enriched in the ¹³C isotope (δ¹³C +7.24…+35.02‰ VPDB), the formation mechanisms of which are currently unknown, were analyzed. The obtained data are consistent with the hypothesis that siderite sedimentation may be associated with local zones of active biogenic destruction of organic matter, but it is suggested that the role of microbial communities in this process may be limited to the reduction of crystalline forms of Fe(III) oxyhydroxides to siderite or replenishment of the Fe(Ⅱ) pool, rather than dissolved inorganic carbon (DIC). In this case, the factor causing the sedimentation of authigenic siderites enriched in the ¹³C isotope may be the supply of DIC or gaseous CO₂ with a deep fluid flow, the isotopic characteristics of which will largely determine the δ¹³C values of carbonates in the sediments of mud volcanoes of Lake Baikal.

In the Siberian Botanical Garden of Tomsk State University, 28 strains of Saccharomyces yeasts were isolated from the bark of Quercus robur and the soil beneath them. Based on the sequencing of the D1/D2 domain and the ITS1 region of rDNA, three strains were assigned to the species S. cerevisiae, and the rest to the species S. paradoxus. Using multigene phylogenetic analysis of nuclear genes (NEJ1, EST2, HDF1, HDF2), the genetic relationship of West Siberian strains of S. paradoxus with European, Far Eastern, North American and Hawaiian populations was studied. According to the results obtained, the West Siberian strains belong to the European population. Apparently, the border between the European and Far Eastern populations of S. paradoxus lies east of Tomsk Oblast.

The development of sustainable agriculture requires reducing the chemical load on agroecosystems. One of the ecological approaches is the use of biopreparations based on rhizobacteria that stimulate plant growth. Inoculation of early wheat (Triticum aestivum L.) sprouts with Herbaspirillum rhizosphaerae UMS-37^T bacteria resulted in an increase in the length of roots and shoots, and also affected the content of proline, malondialdehyde, nitric oxide and catalase activity in sprouts, which indicates the induction of systemic plant resistance mechanisms. The strain H. rhizosphaerae UMS-37^T demonstrated pronounced antifungal activity against field strains of mycelial fungi of the genus Fusarium. The results of this work can be used in the development of environmentally friendly and competitive biopreparations in adaptive agriculture that are capable of activating plant defense systems and controlling fusarium of the most important agricultural crops.