东洞庭湖冬季可培养细菌多样性

Diversity of cultivable bacteria from East Dongting Lake in winter

摘要:

【背景】东洞庭湖地理位置特殊，物种资源丰富，分布着多种具有独特生理生化特征的微生物。【目的】通过可培养方法，获取具备重金属抗性和多环芳烃耐受能力的湖泊细菌资源，并阐明其生理特征。【方法】本研究于2022年1月采集东洞庭湖5个不同地区的40份样品，测定环境因子，开展细菌的分离培养，获得微生物菌株资源，并进行相关性分析。【结果】共分离253株细菌，包括210株重金属抗性菌，43株多环芳烃耐受菌，隶属于42个属，其主要类群是假单胞菌属(Pseudomonas, 46.6%)、伪芽孢杆菌属(Fictibacillus, 7.5%)、假节杆菌属(Pseudarthrobacter, 6.7%)和芽孢杆菌属(Bacillus, 5.1%)。通过复筛，分别获得30株重金属高抗性细菌和7株多环芳烃高耐受能力细菌，包括20株Mg²⁺ (最大耐受浓度为500 mmol/L)、4株Mn²⁺ (最大耐受浓度为500 mmol/L)、 3株Ni²⁺ (最大耐受浓度为30 mmol/L)和3株Zn²⁺(最大耐受浓度为25 mmol/L)抗性细菌；5株萘(最大耐受浓度为0.04 g/mL)和2株菲(最大耐受浓度为0.02 g/mL)耐受菌，其中包括2株潜在新种菌株和1株潜在新属菌株。【结论】5个不同地区样品的细菌多样性存在差异，其中月山、岳阳楼和君山均高于鹿角与南湖。结合环境因子数据分析，发现温度、可溶性颗粒、电导率、溶解氧对样品的细菌群落组成影响较大，pH和盐度较小。本研究获得的具有较高重金属抗性和多环芳烃耐受菌数量较少，可能与东洞庭湖污染防治较好有关。

Abstract:

[Background] East Dongting Lake occupies a special geographical location and harbors abundant species resources, including a variety of microorganisms with unique physiological and biochemical characteristics. [Objective] To obtain the bacterial resources with tolerance to heavy metals and polycyclic aromatic hydrocarbons (PAHs) by the culturable methods and clarify their physiological characteristics. [Method] Forty samples were collected from five different regions of East Dongting Lake in January 2022 for the measurement of environmental factors. The bacteria were isolated, microbial strain resources were obtained, and the correlations of bacteria with environmental factors were analyzed. [Results] A total of 253 bacterial strains were isolated, including 210 strains with tolerance to heavy metals and 43 strains with tolerance to PAHs. The strains belonged to 42 genera, which were dominated by Pseudomonas (46.6%), Fictibacillus (7.5%), Pseudarthrobacter (6.7%) and Bacillus (5.1%). After re-screening, 30 strains with strong tolerance to heavy metals and 7 strains with strong tolerance to PAHs were obtained. Specifically, 20, 4, 3 and 3 strains showed tolerance to Mg²⁺, Mn²⁺, Ni²⁺ and Zn²⁺, with the maximum tolerance concentrations (MTCs) of 500, 500, 30 and 25 mmol/L, respectively. 5 and 2 strains had tolerance to naphthalene and phenanthrene, with the MTCs of 0.04 g/mL and 0.02 g/mL, respectively. Two strains of potentially novel species and one strain of potentially novel genus were identified in this study. [Conclusion] The bacterial diversity varied among the samples from five regions, being higher in Yueshan, Yueyanglou, and Junshan than that in Lujiao and Nanhu. The temperature, total dissolved solids, electrical conductivity, and dissolved oxygen had the greatest influences on the composition of bacterial community, while pH and salinity had the least influences. The low number of strains with strong tolerance to heavy metals and PAHs in this study may be associated with the effective pollution control in East Dongting Lake.