Genomic characterization of Gillisia xinjiangensis sp. nov.: insights into nitrogen metabolism, stress adaptation, and application potential

High-altitude saline lakes host distinctive microbial communities characterized by specialized adaptations to extreme environmental conditions. However, the underlying mechanisms enabling bacterial survival and physiological function in these habitats remain largely unexplored. In this study, a novel Gram-stain-negative, non-motile, rod-shaped bacterium, designated strain Q332^T, was isolated from sediment samples collected from Achikkul Lake, a high-altitude saline lake in Xinjiang, northwestern China. The strain was facultatively aerobic, and grew optimally at 28 °C, pH 7.0, and 3.0 % (w/v) NaCl. Catalase and oxidase activities were positive. Major fatty acids identified in strain Q332^T included anteiso‐C_15:0, anteiso-C_17:1, iso‐C_15:0 and C_16:0. The primary respiratory quinone detected was menaquinone-6 (MK-6). Polar lipid analyses identified phosphatidylethanolamine (PE), one unidentified acyloxyacyl phosphatidylglycerol (APGL), three unidentified lipids (L), three glycolipids (GL), one phospholipid (PL), and four amidolipids (AL). The genomic DNA G + C content is 38.9 %. Genomic characterization revealed a versatile metabolic repertoire, including unique C1-unit metabolic pathways and comprehensive nitrogen cycling capabilities, notably denitrification and assimilatory nitrate reduction. Furthermore, strain Q332^T displayed robust mechanisms for stress adaptation, encompassing tolerance to cold and osmotic stress, defenses against oxidative stress, and resistance to heavy metals. Based on phenotypic, chemotaxonomic, phylogenetic, and genomic features, strain Q332^T is considered to represent a novel species of the genus Gillisia, for which the name Gillisia xinjiangensis sp. nov. is proposed. The type strain is Q332^T (=KCTC 102200^T = MCCC 1K09490^T).