The Antibacterial Activity of Yeasts from Unique Biocenoses.

The replenishment of our stock of substances that possess a therapeutic potential is an important objective in modern biomedicine. Despite the important advances achieved in chemical synthesis, the natural diversity of organisms and microorganisms remains an important source of biologically active compounds. Here, we report the results of our study of a unique collection containing more than 3,000 samples of yeasts found on the Kamchatka Peninsula, the Kuril Islands, and Sakhalin Island, Russia. Since yeast and bacteria coexist in a variety of habitats and can interact with each other, we analyzed the antibacterial activity of the collection of yeast strains towards E. coli cells using a fluorescent bacterial reporter. It was uncovered that the Sakhalin strains for the most part stimulate bacterial growth, while most of the strains found on the Kamchatka Peninsula possess inhibitory properties. Moreover, the samples with the most pronounced antibacterial activity, identified as members of the genus Cryptococcus (Naganishia), were found in a gorge in the vicinity of Pauzhetka village on the Kamchatka Peninsula on wormwood (Artemisia vulgaris) and thistle (Onopordum acanthium). Our data indicate that the combination of a plant and its growth site is important for the emergence of yeast strains capable of secreting antibacterial compounds.