A number of reports on sponge diseases, including from Lake Baikal, have increased dramatically all over the world in recent years. Herewith, there are various hypotheses for sponge mortality. Lubomirskia baikalensis (phylum Porifera, order Spongillida) is a unique endemic freshwater sponge of Lake Baikal that contains a complex community of eukaryotic and prokaryotic endosymbiotic microorganisms. In this work, we present the first results for the effect of anionic surfactants viz. linear alkylbenzene sulphonates (LAS) at low 10 and 20 µg L⁻¹ concentrations on Baikal sponge species and their symbiotic community as an experimental model. A new toxicity test protocol under conditions close to natural is proposed. It uses the sponge amoebocytes called as SA1-cells, which contain eukaryotic green microalgae Chlorella sp. These SA1-cells are shown to be representative indicator in assessing the impact of anionic surfactants. The acute toxic effect resulted in 97–100% sponge cell death in less than 48 h, as well as 100% symbiotic microalgae Chlorella sp. death over 72 h was noted under LAS solution (20 μg L⁻¹) exposure during in vivo experiments. This includes the cell membrane fatty acid changes, change in the cell sizes, cell swelling, and lysis. Long term exposure to LAS solution (10 μg L⁻¹) reflected in cellular stress (oxidative stress) and accompanied by malondialdehyde formation (0.16–2.0 μg g⁻¹ of dry weight) during 14-day exposure was noted. Oxidative stress and mortality of L. baikalensis are associated with their low antioxidant activity. Trolox-equivalent antioxidant capacity (TEAC) found in the range from 0.00031 to 0.00077 Trolox equivalents for these freshwater sponges.

A hydrochemical study of the mineral hydrogen sulfide spring Bezymyanny, located on the coast of Lake Baikal in the Baikal region of the Republic of Buryatia, was carried out. Using the methods of liquid and gas-liquid mass spectrometry, the composition of allotropes of sulfur and organic polysulfides of the source, microbial mats and in their environment was studied. Polysulfides were monitored using previously developed concentration methods using solid-phase extraction and sulfur analysis in natural sulfide mineral waters. During the reduction of sulfates and the subsequent metabolism of hydrogen sulfide, various forms of sulfur are found in bottom sediments - sulfide, elemental, organic, sulfites and thiosulfates. The process of microbiological sulfate reduction is the main mechanism for the formation of reduced sulfur compounds. The presence of organic polysulfides simultaneously with elemental sulfur and hydrogen sulfide suggests that they are active balneological components of hydrogen sulfide mineral waters. The presence of a significant amount of hexasulfur in the water of microbial mats was observed compared to octasulfur in the source.

The main water-extractable component of larch wood is arabinogalactan (AG). Despite a wide range of possible applications as a valuable biological product and high content in wood (up to 25% and higher), its diverse use is hampered by relatively high costs associated with isolation and purification. A significant reduction in the cost of AG can be achieved by using modern membrane technologies (in particular, ultrafiltration) in the complex processing of wood raw materials, including existing sawmill waste. Therefore, an urgent task of optimizing the AG extraction process is to analyze the factors that determine the ultrafiltration conditions of aqueous larch wood extracts and affect the AG yield and the process rate. In this paper, we studied the effect of raw material origin, membrane type and pH on the main ultrafiltration characteristics. It turned out that the origin of the raw material affects both the initial and final ultrafiltration rates. The AG yield for Siberian larch is higher than for Dahurian larch, and the highest yield was observed for secondary wood processing waste. An increase in the pH of the extract increases the ultrafiltration rate. Comparison of hydrophilic membranes based on polysulfonamide and based on a mixture of cellulose acetates, which have close pore sizes, showed the practical similarity of the main characteristics of ultrafiltration, and hydrophobic membranes based on fluoroplastic are not applicable for concentrating aqueous solutions of AG due to the low ultrafiltration rate. The results obtained will allow optimizing the process of obtaining AG in the case of its industrial implementation.