新疆典型硫酸盐和碳酸盐型盐湖嗜盐细菌群落特征及酶活特性

Community structure and enzyme activity characteristics of halophilic bacteria in sulfate- and carbonate-type salt lakes in Xinjiang, China

摘要:

目的 探究嗜盐细菌在中国新疆2种不同类型盐湖中的分布特征及其酶学特性。方法 采集代表性硫酸盐型(七角井)和碳酸盐型(南湖碱湖)盐湖土壤样本，分析其理化性质，并结合培养实验比较2个盐湖的微生物多样性、嗜盐细菌优势类群及其酶活特性。结果 2种类型盐湖的理化性质存在显著差异，七角井盐湖盐度高达227.15 g/kg，高于南湖碱湖的158.61 g/kg，其余pH、HCO₃^-、Cl^-、Mg²⁺和K⁺含量也均有显著差异。Spearman相关性分析发现，Cl^-和Mg²⁺含量与多数优势菌属丰度呈正相关，如海洋杆菌属(Pontibacter)和拟杆菌属(Bacteroides)。细菌16S rRNA基因Illumina MiSeq测序结果显示，南湖碱湖的Simpson和Shannon指数均显著高于七角井，嗜盐细菌分布于37门590属，优势类群包括拟杆菌门(Bacteroidota，33.41%)、芽孢杆菌门(Bacillota，24.71%)、放线菌门(Actinomycetota，14.64%)和假单胞菌门(Pseudomonadota，10.58%)。碳酸盐型南湖以拟杆菌门(Bacteroidota，35.05%)为主，硫酸盐型七角井则以Bacillota (44.66%)为主。南湖碱湖嗜盐细菌丰富度显著高于七角井盐湖，Pontibacter为两盐湖的优势类群。嗜盐菌分离培养结果显示，两盐湖共获得1 130株，隶属于4门7科9属，Bacillota占40.53%、Actinomycetota占36.81%、Pseudomonadota占21.15%。在7种分离培养基中，F6培养基对嗜盐微生物的选择性最佳。两盐湖的优势物种组成相似，多为群落中的低丰度类群，以拟诺卡氏菌属(Nocardiopsis)和芽孢杆菌属(Bacillus)为主。酶活筛选结果显示，46.81%的嗜盐细菌产酯酶，44.07%的菌产纤维素酶，20.88%的菌产淀粉酶，其中Bacillus的综合产酶能力最强。结论 新疆硫酸盐型(七角井)与碳酸盐型(南湖碱湖)盐湖的嗜盐微生物种类存在显著差异，碳酸盐型(南湖碱湖)的嗜盐细菌群落多样性更高，并展现出广泛的酶活性。本研究为盐湖微生物资源的开发利用和生态保护提供了科学依据。

Abstract:

Objective To study the distribution characteristics and enzyme potential of halophilic bacteria in two distinct types of salt lakes located in Xinjiang, China.Methods Soil samples were collected from sulfate-type (Qijiaojing) and carbonate-type (Nanhu Alkaline Lake) salt lakes, and their physicochemical properties were analyzed. The diversity, dominant taxa, and enzyme activities of halophilic bacteria were compared between the two salt lakes by Illumina MiSeq and culture experiments.Results The physicochemical properties of soil differed significantly between the two salt lakes, and the soil salinity of Qijiaojing salt lake (227.15 mg/g) was higher than that of Nanhu Alkaline Lake (158.61 mg/g). Significant differences were also observed in pH, HCO₃^-, Cl^-, Mg²⁺, and K⁺ content. Spearman correlation analysis revealed positive correlations between Cl^- and Mg²⁺ content and the relative abundance of dominant bacterial genera such as Pontibacter and Bacteroides. Illumina MiSeq results of bacterial 16S rRNA genes indicated that the Simpson and Shannon indexes of Nanhu Alkaline Lake were significantly higher than those of Qijiaojing. Halophilic bacteria belonging to 590 genera of 37 phyla were identified, including Bacteroidota (33.41%), Bacillota (24.71%), Actinomycetota (14.64%), and Pseudomonadota (10.58%). The dominant phylum was Bacteroidota (35.05%) in Nanhu Alkaline Lake, while it was Bacillota (44.66%) in Qijiaojing. The richness of halophilic bacteria in Nanhu Alkaline Lake exceeded that in Qijiaojing, with Pontibacter identified as the dominant genus in both lakes. A total of 1 130 strains were obtained from two salt lakes, belonging to 9 genera, 7 families of 4 phyla, among which Bacillota, Actinomycetota, and Pseudomonadota accounted for 40.53%, 36.81%, and 21.15%, respectively. The results of culture experiments with seven different media indicated that the F6 medium exhibited the highest selectivity towards halophilic microorganisms. Culture experiments demonstrated similar dominant species in both lakes, primarily comprising low-abundant bacteria, such as Nocardiopsis and Bacillus. Enzyme activity screening results revealed that 46.81%, 44.07%, and 20.88% of halophilic bacteria produced esterase, cellulase, and amylase, respectively, with Bacillus exhibiting the highest overall enzyme production capability.Conclusion There are significant differences in the halophilic bacterial diversity between sulfate- and carbonate-type salt lakes in Xinjiang. The halophilic bacteria in the carbonate-type Nanhu Alkaline Lake salt lake have higher diversity and exhibit stronger enzyme activities. This investigation contributes valuable insights for the advancement and sustainable utilization of microbial resources and the ecological preservation in salt lakes.