Screening, Isolation, and Identification of a Haloalkaliphilic Bacterium from the Phycosphere: Genetic Characterization of Salt-Alkali Tolerance Mechanisms

本研究从球等鞭金藻(Isochrysis galbana)藻际环境中分离获得一株耐盐碱菌株Microbacterium paraoxydans IGS-10，通过生理生化特性分析、16S rRNA系统发育学鉴定及全基因组测序技术，系统解析其耐盐碱分子机制。实验结果显示，IGS-10在NaCl浓度≤6% (w/v)和pH 7-10范围内均能稳定生长，表明该菌株对高盐碱环境具有显著适应性。基因组测序揭示其基因组大小约为3.84 Mb，GC含量70.35%，并携带30余个与耐盐碱密切相关的功能基因，包括离子转运系统基因以及相容性溶质(甜菜碱和海藻糖)合成基因。本研究不仅丰富了藻际微生物资源库，还为解析极端环境微生物的适应性进化机制提供了关键分子证据，对耐盐碱微生物资源的农业与工业应用具有潜在参考价值。In this study, a saline-tolerant strain Microbacterium paraoxydans IGS-10 has been isolated from Isochrysis galbana in the algal environment. Through physiological and biochemical analysis, 16S rRNA phylogenetic identification and whole genome sequencing technology, Microbacterium Paraoxydans IGS-10 has been obtained. The molecular mechanism of saline-alkali resistance was systematically analyzed. The experimental results showed that IGS-10 could grow stably in the range of NaCl concentration ≤6% (w/v) and pH 7-10, indicating that the strain had remarkable adaptability to high saline-alkali environment. Genome sequencing revealed that its genome size was about 3.84 Mb, GC content was 70.35%, and it carried more than 30 functional genes closely related to saline-alkali tolerance, including ion transport system genes and compatible soles (betaine and trehalose) synthesis genes. This study not only enriches the algal microbial resource pool, but also provides key molecular evidence for the analysis of the adaptive evolutionary mechanism of microorganisms in extreme environments, and has potential reference value for the agricultural and industrial application of saline-tolerant microbial resources.