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Growth of human population leads to many global and medical problems. The problems include the crisis of health, antibiotic resistance, drug discovery, etc. Increasing antimicrobial resistance of microorganisms results in the need to screen natural products (incl. antibiotics and antimicrobial peptides) and their producers in different ecological niches. The purpose of this study was to estimate antibiotic activity and biotechnological potential of rare actinobacteria Nocardiopsis sp. The strain was isolated from Okhotnichya cave located in Siberia. Here, we cultivated the strain at 3 temperature modes (13 °C, 28 °C, 37 °C) in 11 liquid nutrient (rich and poor) media. Using modern assays of liquid chromatography and high-resolution mass spectrometry, we estimated the content and number of produced natural products, distribution of their masses, and potential rate of novel secondary metabolites. We demonstrated that minimal nutrient media with l-asparagine and SM25 media with malt extract were less productive at current experimental parameters. As it was shown, this strain was characterized by antibiotic properties against Bacillus subtilis when cultivated at 28 °C. Also, weak antibiotic activity of crude extracts was found in strain cultivation at 13 °C. Also, we detected a high number of novel amphiphilic and hydrophobic NPs produced by this strain. We demonstrated both the influence of the nutrient media composition and cultivation temperature on biosynthetic capabilities of rare strain Nocardiopsis sp. Finally, high level of natural products that were predicted as novel confirms high biotechnological value of rare genera of Actinobacteria that could be explained by the evolution of microorganisms in the isolated environment of cave ecosystem. [ABSTRACT FROM AUTHOR]

The lipid and fatty acid content of benthopelagic scavenging amphipods Ommatogammarus flavus and O. albinus from different depths of Lake Baikal were studied. These amphipods, known to move across a wide range of depths in Lake Baikal, had a relatively high level of total lipids (up to 46% dry weight) in comparison to other aquatic amphipods. This high level of total lipids resulted from a high concentration of storage lipids (triacylglycerols). The monounsaturated 18:1(n-9) acid in combination with 16:1(n-7), and 18:1(n-7) fatty acids were dominant in the amphipods, reflecting their deep-dwelling scavenging mode of life. Local groups of amphipods were distinguished along a Lake Baikal depth gradient based on the primarily diet-associated differences in fatty acid composition. [ABSTRACT FROM AUTHOR]

The current study evaluated the possible toxic effects of the water-soluble fraction of crude oil on the general cellular stress-response mechanisms of two dominant representatives of Lake Baikal's littoral community, the endemic amphipod species Eulimnogammarus verrucosus and E. cyaneus. The acute toxicity effects on the cellular stress-response mechanisms of amphipods were studied in the laboratory by exposing amphipods in water from Lake Baikal to addition of a water-soluble fraction of crude oil at concentrations considered safe for the aquatic environment. The present study found that even short-term exposure to a water-soluble fraction of crude oil at concentration of 50 µg/L, established as the threshold limit for fishery and aquaculture water reservoirs in the Russian Federation, directly affected the general stress-response markers HSP70 and lipid peroxidation and significantly changed the activity of antioxidant enzymes in both studied species. This result confirms the high sensitivity of Baikal endemics to crude oil. Thus, it also indicates that established standards and threshold limit values of oil concentrations estimated for ecological monitoring of general water reservoirs cannot be applied directly to the unique Lake Baikal ecosystem. [ABSTRACT FROM AUTHOR]