Characteristics of Psychrotolerant Bacteria Isolated from Clay Organogenic Deposits of Mramorny Cave (Primorsky Territory)

Abstract

A cultivated community of bacteria of the genus Pseudomonas was researched in clayey organogenic deposits of the Mramorny Cave (Primorsky Territory). The bacterial strains studied in this work are eurythermal and psychrotolerant. Their phylogenetic affiliation was found by high throughput sequencing of 16S rRNA gene fragments. It is known that bacteria of the genus Pseudomonas represent all the Earth ecological niches and, accordingly, have a wide range of adaptive functions. Using microscopy methods, a change in the nature of mobility and the cell size stability with changes in the temperatures of cultivating bacteria were established. The studied strains are of scientific and practical interest due to the enzymatic activity detection to several substrates simultaneously at different temperatures (25 and 4℃), as well as the ability to secrete cold active pectinase, protease and lipase. However, phosphate-solubilizing activity both at 4 and at 25℃ became preferable for the strains. The Mramorny Cave is karst and is characterized by carbonate karst, which explains the preference for the studied strains in calcium phosphate. An analysis of the obtained data shows that the collection of cultivated bacteria obtained by us includes both typical psychrotolerant ones, which exhibit enzymatic activity under conditions of optimal growth temperature, and unique ones, capable of synthesizing a wide range of enzymes under conditions not characteristic of its optimum growth.