Taxonomic composition and physiological and biochemical properties of cultivated microorganisms isolated from kudurite rocks of the Primorsky Krai and the Republic of Altai (Russia)

Abstract

The reason for the consumption of rocks (kudurits) by wild animals has not yet been identified. One of the hypotheses of geophagy is a microbiological factor, i.e. rocks can be a source of microorganisms useful for wild animals. In this work, the composition of cultured microorganisms of kudurits of Primorsky Krai and the Altai Republic, as well as some physiological and biochemical properties of the isolated bacteria were studied using molecular genetic analysis of the 16S RNA gene. It has been shown that the studied breeds contain a high amount of physiological groups of bacteria (saprophytic, ammonifying, nitrifying, silicate, hydrolytic) and yeasts (106-109 cells/ml) useful for animals. Among the isolated culturable microorganisms in the curls of Primorsky Krai, representatives of the genus Pseudomonas, Bacillus, Rhodotorula, Paenibacillus, and Stenotrophomonas predominated. The bacteria of the genus Bacillus, Chryseobacterium, and Streptomyces dominated in the edible soils of Altai. Among the isolates, non-pigmented, motile (35–70 %) catalase-positive (86–91 %) and oxidase-negative (68–76 %) rods (67–90 %) predominated. All cultures were characterized by a high level of extracellular enzymatic activity, especially in relation to such substrates as casein (57–75 %), starch (57–60 %), urea (43–45 %). The isolated microorganisms are able to develop in a wide range of temperatures (5–50 °C), pH (5−12), NaCl concentration (1–18 %) and utilize a wide range of carbohydrates and alcohols. It has been established that the microorganisms and biologically active compounds they produce can be a factor that encourages animals to instinctively consume rocks. High antibiotic activity of the isolated cultures has been noted against opportunistic bacteria Staphylococcus aureus, Micrococcus luteus and phytopathogenic fungi Fusarium oxysporum.

Keywords

• Bacteria
• Animals
• Geophagy
• Yeast
• Antibiotic
• Enzymatic activity