一株可增强莱茵衣藻耐盐能力细菌MEZX29的分离与鉴定

【背景】水体中的藻类、细菌及这些微生物之间的相互作用对水体生态系统的功能有着重要作用。近年来，一些河流、湖泊等淡水资源的盐渍化不断加重，对水体生态系统造成严重影响。然而，高盐胁迫条件如何影响藻类与其他细菌的相互作用，以及是否存在能够促进藻类耐盐能力的有益细菌等问题尚未得到深入研究。【目的】分离和鉴定可以促进淡水藻类莱茵衣藻抗盐能力的细菌，并开展相关机制分析。【方法】通过富集培养、筛选和共接种实验，获得可以促进衣藻耐盐的细菌；基于活细胞浓度、叶绿素含量等参数评价衣藻在不同条件下的生长能力；对菌株进行16S rRNA基因序列分析和基因组分析，预测其可能的菌藻相互作用机制。【结果】获得一株在250-290 mmol/L NaCl条件下可以显著增强衣藻耐盐能力的菌株MEZX29，16S rRNA基因序列分析表明，该菌可能属于Rhodococcus qingshengii；基因组分析结果表明，该细菌含有参与糖代谢、乙烯合成、生物膜形成等途径的基因，这些基因可能在促进衣藻抗盐过程中起到重要作用。【结论】Rhodococcus qingshengiiMEZX29可以增强莱茵衣藻21gr抵抗高盐胁迫的能力，为研究藻类与其他微生物之间的有益相互作用提供了新的材料。

Isolation and identification of bacterial strain MEZX29 that can enhance the salt tolerance of Chlamydomonas reinhardtii

Background] Algae, bacteria and their interspecies interactions play important roles in aquatic ecosystem. In recent years, salinization of some rivers, lakes and other freshwater resources has become more serious, which greatly impacts the aquatic ecosystem. However, how salt stress influences the algae-bacteria interaction and whether certain bacteria can enhance algal salt tolerance remain unclear. Objective] To isolate and identify the bacteria that can promote the salt tolerance of freshwater alga, Chlamydomonas reinhardtii, and analyze the relevant mechanism. Methods] Effective bacteria were screened through enrichment culture, isolation and co-culture experiments. The algal growth ability under different conditions was assessed based on cell concentration, chlorophyll content and other parameters. In addition, 16S rRNA gene sequence analysis and genome sequence analysis were carried out to predict the possible mechanism of algae-bacteria interaction. Results] A bacterial strain, MEZX29, was isolated, which could significantly enhance the salt tolerance of C. reinhardtii under the condition of 250-290 mmol/L NaCl. The 16S rRNA gene sequence analysis indicated that MEZX29 might belong to Rhodococcus qingshengii. The genome sequence analysis showed that MEZX29 contained the genes involved in glucose metabolism, ethylene metabolism, and biofilm formation, which might play roles in this salt tolerance enhancement. Conclusion] R. qingshengii strain MEZX29 could enhance the salt tolerance of C. reinhardtii, which provided a new material for studying the beneficial interaction between algae and microorganisms.