Genome-guided characterization of Nocardiopsis lopnurensis sp. nov. and genomic features potentially associated with halotolerance and alkalitolerance

Saline-alkaline soils select for microorganisms capable of tolerating high salinity and alkaline pH. Here, strain TRM 82005ᵀ, isolated from Lop Nur, Xinjiang, China, was characterized using polyphasic taxonomy and comparative genomic analysis with seven related Nocardiopsis type strains. The strain formed branched substrate and aerial mycelia that fragmented into rod-shaped or suboval elements. In independent assays, it grew at 4–50°C, pH 6.0–11.0 and 1–15% (w/v) NaCl, with optima of 28°C, pH 9.0 and 5% (w/v) NaCl. Its 6.19-Mb draft genome had a DNA G+C content of 70.33 mol% and contained 5,394 predicted coding sequences. Genome relatedness to the closest of the seven reference type-strain genomes included in the fixed comparative dataset, Nocardiopsis sinuspersici DSM 45277ᵀ, was 90.25% average nucleotide identity and 37.2% digital DNA–DNA hybridization (GGDC formula d4; 95% confidence interval, 34.8–39.8%), below accepted species thresholds. Curated annotations identified candidate functions related to Na⁺/H⁺ antiport, K⁺ uptake, compatible-solute metabolism, pH homeostasis and oxidative-stress defence. CAZy analysis predicted 166 carbohydrate-active enzyme domains, and archived antiSMASH output identified 15 putative biosynthetic gene clusters; cross-strain BGC counts were interpreted descriptively because different antiSMASH versions were used. These data support the proposal of Nocardiopsis lopnurensis sp. nov. and identify genomic features potentially associated with halotolerance and alkalitolerance. Their expression, functional contributions and coordinated activity under combined saline and alkaline conditions remain to be tested experimentally.