Corynebacterium halotolerans sp. nov., isolated from saline soil in the west of China

Researchers isolated a novel halotolerant bacterium from saline soil in Xinjiang Province, China, and designated it strain YIM 70093T. The organism is a Gram-positive, non-motile, rod-shaped actinobacterium belonging to the genus Corynebacterium. It exhibits remarkable salt tolerance, growing optimally at 10% KCl and tolerating up to 25% KCl, NaCl, or MgCl₂. The strain grows best at pH 7.2 and 28°C. Comprehensive analysis including 16S rRNA gene sequencing, fatty acid profiling, menaquinone composition, and biochemical testing revealed sufficient differences from known Corynebacterium species to warrant classification as a new species. The bacterium shows 93.5–95.8% 16S rRNA sequence similarity to closest relatives, with >3% sequence divergence from validly named Corynebacterium species. Key distinguishing features include positive β-glucuronidase activity and negative α-glucosidase activity, differing from close relatives. The DNA G+C content is 63 mol%. Based on these molecular and phenotypic characteristics, the authors propose the name Corynebacterium halotolerans sp. nov. for this halotolerant soil isolate.

Key findings

• A novel halotolerant Corynebacterium species, C. halotolerans, was isolated from saline soil in western China with optimal growth at 10% KCl and tolerance up to 25% KCl/NaCl/MgCl₂
• 16S rRNA sequence analysis showed >3% divergence from known Corynebacterium species, supporting novel species status
• The bacterium exhibits distinctive biochemical features including positive β-glucuronidase activity and negative α-glucosidase activity, differentiating it from phylogenetically closest relatives
• Cell wall analysis confirmed meso-diaminopimelic acid and typical Corynebacterium lipid and fatty acid profiles with short-chain mycolic acids (C₃₂–C₃₆)