The diversity and antibiotic properties of actinobacteria associated with endemic deepwater amphipods of Lake Baikal.

The emergence of pathogenic bacteria resistant to antibiotics increases the need for discovery of new effective antimicrobials. Unique habitats such as marine deposits, wetlands and caves or unexplored biological communities are promising sources for the isolation of actinobacteria, which are among the major antibiotic producers. The present study aimed at examining cultivated actinobacteria strains associated with endemic Lake Baikal deepwater amphipods and estimating their antibiotic activity. We isolated 42 actinobacterial strains from crustaceans belonging to Ommatogammarus albinus and Ommatogammarus flavus. To our knowledge, this is the first report describing the isolation and initial characterization of representatives of Micromonospora and Pseudonocardia genera from Baikal deepwater invertebrates. Also, as expected, representatives of the genus Streptomyces were the dominant group among the isolated species. Some correlations could be observed between the number of actinobacterial isolates, the depth of sampling and the source of the strains. Nevertheless, >70% of isolated strains demonstrated antifungal activity. The dereplication analysis of extract of one of the isolated strains resulted in annotation of several known compounds that can help to explain the observed biological activities. The characteristics of ecological niche and lifestyle of deepwater amphipods suggests that the observed associations between crustaceans and isolated actinobacteria are not random and might represent long-term symbiotic interactions.

Actinobacteria possessing antimicrobial and antioxidant activities isolated from the pollen of scots pine (Pinus sylvestris) grown on the Baikal shore.

Isolated ecosystems existing under specific environmental conditions have been shown to be promising sources of new strains of actinobacteria. The taiga forest of Baikal Siberia has not been well studied, and its actinobacterial population remains uncharacterized. The proximity between the huge water mass of Lake Baikal and high mountain ranges influences the structure and diversity of the plant world in Siberia. Here, we report the isolation of eighteen actinobacterial strains from male cones of Scots pine trees (Pinus sylvestris) growing on the shore of the ancient Lake Baikal in Siberia. In addition to more common representative strains of Streptomyces, several species belonging to the genera Rhodococcus, Amycolatopsis, and Micromonospora were isolated. All isolated strains exhibited antibacterial and antifungal activities. We identified several strains that inhibited the growth of the pathogen Candida albicans but did not hinder the growth of Saccharomyces cerevisiae. Several isolates were active against Gram-positive and Gram-negative bacteria. The high proportion of biologically active strains producing antibacterial and specific antifungal compounds may reflect their role in protecting pollen against phytopathogens.

Composition of nutrient media and temperature of cultivation imposes effect on the content of secondary metabolites of Nocardiopsis sp. isolated from a Siberian Cave.

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.

Draft Genome Sequence of Streptomyces sp. Strain IB2014011-1, Isolated from Trichoptera sp. Larvae of Lake Baikal.

Unique ecosystems with specific environmental conditions have been proven to be a promising source for isolation of new actinobacterial strains. Ancient Lake Baikal is one of the greatest examples of an ecosystem with high species biodiversity and endemicity caused by long-lasting isolated evolution and stable environmental conditions. Herein we report the draft genome sequence of Streptomyces sp. strain IB2014011-1, which was isolated from insect Trichoptera sp. larvae collected at the bottom of Lake Baikal.

Actinobacteria Isolated from an Underground Lake and Moonmilk Speleothem from the Biggest Conglomeratic Karstic Cave in Siberia as Sources of Novel Biologically Active Compounds.

Actinobacteria isolated from unstudied ecosystems are one of the most interesting and promising sources of novel biologically active compounds. Cave ecosystems are unusual and rarely studied. Here, we report the isolation and characterization of ten new actinobacteria strains isolated from an ancient underground lake and moonmilk speleothem from the biggest conglomeratic karstic cave in Siberia with a focus on the biological activity of the obtained strains and the metabolite dereplication of one active strain. Streptomyces genera isolates from moonmilk speleothem demonstrated antibacterial and antifungal activities. Some of the strains were able to inhibit the growth of pathogenic Candida albicans.