Researchers evaluating haloalkaliphilic bacteria isolated from saline-alkali soil have identified two novel species belonging to the genus Halalkalibacter, designated Halalkalibacter haasae sp. nov. and Halalkalibacter salibacillus sp. nov. The investigation employed a polyphasic approach to evaluate the taxonomic positions of strains HAAS-P013T and HAAS-P014T while providing genomic insights into the genus Halalkalibacter.
Strains HAAS-P013T and HAAS-P014T are Gram-positive, aerobic, motile, and rod-shaped microorganisms. Phylogenetic analyses alongside 16S rRNA gene sequence analyses assigned both strains directly to the genus Halalkalibacter.
The two strains exhibited distinct environmental tolerance ranges and optimal conditions during physiological testing. Strain HAAS-P013T showed growth at temperatures ranging from 12 to 45 °C with an optimum at 32 °C, tolerated pH levels from 6.0 to 11.0 with an optimum at pH 10.0, and demonstrated tolerance to NaCl concentrations of up to 15% (w/v). Strain HAAS-P014T grew across the same temperature range of 12 to 45 °C but showed an optimum temperature of 37 °C, grew at pH 7.0 to 11.0 with an optimum at pH 10.0, and tolerated higher salinity with NaCl concentrations up to 20% (w/v).
Chemotaxonomic characterization identified shared and distinguishing biochemical profiles between the two isolates. Both strains consist of meso-2,6-diaminopimelic acid, MK-6 and MK-7 as menaquinones, and anteiso-C15:0 and C16:0 as dominant fatty acids. Their polar lipids include diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and an unidentified lipid; however, strain HAAS-P013T contained two additional unidentified phospholipids, whereas strain HAAS-P014T contained one additional unidentified phospholipid.
Whole-genome assessments revealed the presence of multiple genes potentially involved in osmotic and alkaline stress responses in both strains. Genomic comparisons showed that average nucleotide identity and digital DNA-DNA hybridization values among strain HAAS-P013T, strain HAAS-P014T, and other Halalkalibacter species remained below the species delineation threshold values of 95 to 96% and 70%, respectively. Based on these genomic and polyphasic results, the strains represent two novel species proposed as Halalkalibacter haasae sp. nov., with type strain HAAS-P013T (= KCTC 43869T = GDMCC 1.6158T), and Halalkalibacter salibacillus sp. nov., with type strain HAAS-P014T (= KCTC 43870T = GDMCC 1.6094T).
Subject of Research: Taxonomic and genomic characterization of novel Halalkalibacter species
Article Title: Genomic insights into the genus Halalkalibacter and proposal of two novel Halalkalibacter species, Halalkalibacter haasae sp. nov., and Halalkalibacter salibacillus sp. nov
Article References: Wang, J., Zhu, K., Jin, P., Wu, K., Quadri, S. R., Narsing Rao, M. P., Zhao, D., & Wang, S. (2026). Genomic insights into the genus Halalkalibacter and proposal of two novel Halalkalibacter species, Halalkalibacter haasae sp. nov., and Halalkalibacter salibacillus sp. nov. BMC Microbiology. https://doi.org/10.1186/s12866-026-05785-z
Image Credits: AI Generated
DOI: 10.1186/s12866-026-05785-z
Keywords: Halalkalibacter, Halalkalibacter haasae, Halalkalibacter salibacillus, haloalkaliphiles, saline-alkali soil, bacterial taxonomy, comparative genomics, polyphasic taxonomy, Genomic, insights, genus, proposal
News Source: Drew Townsend. (November 6, 2026). Two Novel Halalkalibacter Bacterial Species Identified in Saline-Alkali Soil. Scienmag.
