Halosimplex amylolyticum sp. nov., Halosimplex halobium sp. nov., Halosimplex marinum sp. nov., Halosimplex rarum sp. nov., Halovenus amylolytica sp. nov., Halovenus halobia sp. nov., and Halovenus marina sp. nov., halophilic archaea isolated from a marine tidal flat, a marine solar saltern, three coarse sea salts, and two saline lakes

Abstract

Seven novel halophilic archaeal strains DYHT-AS-1^T, GDY60^T, TS25^T, XH63^T, SHR40^T, SYNS179^T, and ZY30^T were isolated from tidal flat, saline lakes, marine solar saltern and coarse sea salts from different regions of China. Metagenomic and amplicon analyses indicated that the abundance of these seven strains in respective habitats was low. Phylogenetic and comparative genomic analyses indicated that strains DYHT-AS-1^T, GDY60^T, TS25^T, and XH63^T formed a tight cluster with Halosimplex species, exhibiting high 16S rRNA gene sequence similarity (90.4–99.4 %). The ANI, dDDH, and AAI values among these four strains and current Halosimplex species were 80.8–92.3 %, 24.5–53.3 %, and 77.8–91.5 %, respectively. Strains SHR40^T, SYNS179^T, and ZY30^T were related to Halovenus species, with 16S rRNA gene sequence similarities ranging from 88.8 % to 98.4 %. The ANI, dDDH, and AAI values among these three strains and current Halovenus species were 69.9–77.8 %, 19.4–21.5 %, and 62.1–78.1 %, respectively. These values are significantly lower than the thresholds for species demarcation. The optimal growth conditions for these seven strains in terms of NaCl, MgCl₂, temperature, and pH were 3.1–3.4 M, 0.05–0.5 M, 35–40 °C, and 6.5–7.5, respectively. According to phenotypic differences in nutrition, biochemical activity, and antibiotic sensitivity, these seven strains can be distinguished from their related species. Based on the above results, strains DYHT-AS-1^T, GDY60^T, TS25^T, and XH63^T represent four new species of the genus Halosimplex, and strains SHR40^T, SYNS179^T, and ZY30^T represent three novel species of the genus Halovenus.