新疆两盐湖可培养极端嗜盐菌组成及功能多样性研究

Composition and functional diversity of extreme halophiles isolated from two salt lakes in Xinjiang

摘要:

【目的】通过分析不同成盐类型盐湖中的极端嗜盐菌群落组成差异，探究可培养极端嗜盐菌的功能特性。【方法】采集新疆硫酸盐型盐湖七角井和碳酸盐型盐湖南湖的土壤样品，通过平板稀释涂布法分离极端嗜盐菌，经过形态学观察、特征分析获取代表菌株，通过耐盐性测定和16S rRNA基因序列测序等对代表菌株进行鉴定，并对极端嗜盐菌的蛋白酶、淀粉酶、纤维素酶和酯酶活性进行筛选，同时检测苯酚降解能力。【结果】本研究共获得1 679株极端嗜盐菌，代表菌株45株，隶属于5门14个属，古菌数量(70.58%)明显多于细菌，最优盐浓度生长范围为18.4%–20.0%。在属水平上，盐湖中优势类群为古菌的Haloterrigena属(32.94%)和Natrialba属(26.03%)，以及细菌的Aquisalimonas属(9.85%)和Aliifodinibius属(8.10%)。两盐湖中，盐度较低的南湖物种丰富度高于七角井盐湖，古菌物种组成相似，均以Haloterrigena属为主；细菌群落组成有差异，南湖以Aquisalimonas属为主，而七角井以Aliifodinibius属为主。功能筛选表明，盐湖中80%的嗜盐菌功能筛选至少有一种为阳性，产淀粉功能酶菌株占42.58%，多属于Natrialba属。产蛋白酶、纤维素酶和脂肪酶的菌株分别占9.71%、9.29%和7.21%，降解苯酚菌株占11.14%。【结论】本研究揭示了新疆盐湖中可培养极端嗜盐菌的多样性，古菌是优势菌群，细菌种类多样，菌株各类功能酶活性显著，同时，优势的Natrialba、Haloterrigena、Aquisalimonas和Aliifodinibius属菌株均极具应用潜力，可为今后研究应用提供和丰富了菌种资源，具有较大的挖掘潜力。

Abstract:

[Objective] To investigate the functional characteristics of cultivable extreme halophiles by analyzing the differences of community composition of extreme halophiles in salt lakes with different types of salt formation. [Methods] Soil samples were collected from Qijiaojing Salt Lake (sulfate type) and Nanhu Salt Lake (carbonate type) in Xinjiang, and extreme halophiles were isolated by the dilution plating method. By morphological observation and characteristic analysis, the representative strains were screened. The salt-tolerance of the strains was tested and the 16S rRNA gene sequencing was performed. Functional activities of the extreme halophiles were also detected, including protease, amylase, cellulase and lipase activities as well as phenol degradation ability. [Results] A total of 1 679 strains of extreme halophiles were obtained, and 45 representative strains were screened, which belonged to 5 phyla and 14 genera, and the number of archaea (accounting for 70.58%) was significantly more than that of bacteria. The optimal salt concentration for growth was in the range of 18.4%–20.0%. At the genus level, the dominant groups were Haloterrigena (32.94%) and Natrialba (26.03%) in archaea, and Aquisalimonas (9.85%) and Aliifodinibius (8.10%) in bacteria. In the two salt lakes, the species richness of Nanhu Salt Lake with lower salinity was higher than that of Qijiaojing Salt Lake, but the composition of archaea species was similar, mainly Haloterrigena. There were differences in bacterial community composition; specifically, Aquisalimonas was dominant in Nanhu Salt Lake, while Aliifodinibius was dominant in Qijiaojing Salt Lake. Functional diversity screening showed that the total positive rate was 80%, and 42.58% of the strains produced amylase and were classified into Natrialba. Extreme halophiles producing protease, cellulase and lipase accounted for 9.71%, 9.29% and 7.21%, respectively, and phenol degrading strains occupied 11.14%. [Conclusion] This study revealed the diversity of cultivable extreme halophiles in Xinjiang salt lakes. Archaea was the dominant group and there were also diverse bacterial species, displaying significant activity of various functional enzymes. Additionally, the dominant Natrialba, Haloterrigena, Aquisalimonas and Aliifodinibius had great application potential, which could enrich bacterial resources for future research and application, and were worthy mining.