Morphological and Molecular Characterization of Psychrobacter cryohalolentis Isolated from Chestnut Soils in Türkiye

Abstract Psychrobacter cryohalolentis was first isolated from Siberian permafrost in 2006, with the type strain being K5. It is an important species because it is both halotolerant and psychrotolerant. This study describes and characterizes P. cryohalolentis, isolated from the soil of a chestnut forest in Kastamonu, Türkiye, in October 2024. Morphological examinations by light microscopy and scanning electron microscopy revealed the bacterium to be Gram-negative, non-motile, and coccobacillus-like. The bacterial dimensions were measured to be 0.8–1.0 µm in width and 1.1–1.5 µm in length. Next-generation sequencing of the 16S rRNA gene demonstrated 99.86% sequence identity with a South Korean strain. Phylogenetic analysis revealed two distinct clades within the species, with the isolate under study grouping into the smaller Clade 2. This observation indicates significant genetic differentiation, which may be attributed to environmental or geographic factors. Experiments conducted to determine the limits of temperature and salinity tolerance have shown that the species grows between 4 and 30°C (optimum 22°C) and at salt concentrations of 0 to 11% NaCl (optimum 1% NaCl). This species, resistant to cold environments and with an optimum survival temperature of 22°C, was isolated for the first time from the soil of a chestnut forest in Türkiye in October, when air temperatures were 18°C, and has the potential to be added to the literature as a new distribution record. This new strain can withstand saline and cold environments and highlights its potential for use in biotechnological processes.