Alkalihalobacillus okhensis is a halo-alkaliphile with optimal growth at pH 10 and 5% NaCl. Phylogenetic analysis revealed habitat-dependent segregation of Bacilli, with all the alkalihalophiles forming a separate clade. It uses acidification of the external medium and pH-dependent cell wall reinforcement to survive sodic environments. Interestingly, comparative genome analysis revealed the genome encodes surface proteins with a high proportion of acidic amino acids compared to their orthologs of B. subtilis, a piece of direct evidence for adaptive evolution. It has a relatively higher number of genes involved in the metabolism of osmolytes and sodium-dependent transporters when compared to B. subtilis. Growth of Alkalihalobacillus okhensis strain Kh10-101 ^T (hereafter A. okhensis) is Na⁺ dependent, with a minimum of 4% NaCl at neutral pH, but 0.5% NaCl is enough at pH 10. It tolerated a sudden increase in salt concentration and exhibited an elongated phenotype but could not tolerate a sudden pH shift from 7 to 11. The cell envelope got damaged, confirming that the pH regulation through cell wall reinforcement is key to survival at a high-pH condition. We report for the first time a comprehensive genome analysis of Bacilli to delineate the mechanisms evolved for adaptation to halo-alkaline conditions.

Alkalihalobacillus okhensis是一种卤代嗜碱菌，在 pH 10 和 5% NaCl 条件下具有最佳生长。系统发育分析揭示了芽孢杆菌的栖息地依赖性分离，所有嗜碱嗜盐菌形成一个单独的进化枝。它使用外部介质的酸化和 pH 依赖性细胞壁强化来在钠环境中生存。有趣的是，比较基因组分析显示，与枯草芽孢杆菌的直系同源物相比，基因组编码的表面蛋白具有高比例的酸性氨基酸，这是适应性进化的直接证据。与枯草芽孢杆菌相比，它具有相对较高数量的参与渗透物和钠依赖性转运蛋白代谢的基因。的增长Alkalihalobacillus okhensis菌株 Kh10-101  ^T（以下简称A. okhensis）是 Na ⁺依赖性的，在中性 pH 值下最少 4% NaCl，但在 pH 10 时 0.5% NaCl 就足够了。它耐受盐浓度的突然增加并表现出拉长的表型，但不能耐受从 7 到 11 的突然 pH 变化。细胞膜受损，证实通过细胞壁强化调节 pH 值是在高 pH 条件下存活的关键。我们首次报告了芽孢杆菌的综合基因组分析，以描述为适应卤代碱性条件而进化的机制。