长潭水库铁锰含量与环境因子的季节性变化相关性分析及铁锰氧化菌群的富集培养

Correlation between concentration of iron/manganese ion and environmental factors, and enrichment of iron-and manganese-oxidizing bacteria in Changtan Reservoir during different seasons

摘要:

【背景】目前对水库水体污染原因的研究往往专注于水体的富营养化、pH值、溶解氧、氨氮、菌落总数指标的变化，而重金属含量与环境因子的季节性变化相关性分析研究较少，同时对于典型季节原位微生物种群的多样性差异研究尚未见报道。【目的】研究浙江省台州市长潭水库底部水中正二价金属离子(二价锰离子Mn²⁺；二价铁离子Fe²⁺)浓度与不同环境因子的季节性变化规律，并对其相关性进行分析；富集平水期(2月)和丰水期(8月)水库底部水体中功能微生物菌群，分析其种类和丰度的差异。【方法】分别检测12个月的水库水Mn²⁺和Fe²⁺浓度及多种环境因子(水体溶解氧浓度、pH值、总磷浓度、浊度、水库环境温度及降水量)，过滤并富集培养水库底部水体的功能微生物菌群，对其16S rRNA基因V3-V4区测序并分析其菌群结构。【结果】长潭水库水中Mn²⁺和Fe²⁺浓度呈季节性变化，每年的春夏交替季节水体中铁锰含量从零开始慢慢升高，至夏秋高温季节水体中Mn²⁺和Fe²⁺浓度达到最高值，然后慢慢降低，至秋末冬初检测不到含量。在检测的多种环境因子中，水体溶解氧浓度、水库环境温度及降水量呈明显的季节性规律变化。Mn²⁺和Fe²⁺浓度与温度、降水量和浊度有正相关性，与溶解氧浓度、pH值和总磷浓度有负相关性，其中在正负相关性分析中两种金属离子的浓度与溶解氧浓度的相关性最强，其次是环境温度及降水量。丰水期和平水期中富集获得的功能微生物菌群的种类和丰度差异很大，从属水平上分类，丰水期时菌群只包含不动杆菌(Acinetobacter)和鲑色沉积物杆状菌(Sediminibacterium)这2个属的菌株，含量各占约50%；平水期时菌群则主要由杆菌属(Bacillariophyta) (47.62%)和Limnohabitans(9.52%)等9个属的菌株构成。富集获得的平水期和丰水期的两个可培养的菌群均具有去除水库水中Mn²⁺的功能，去除率分别约为35.9%和11.4%。【结论】长潭水库底部水体中Mn²⁺和Fe²⁺浓度与不同环境因子均呈季节性规律变化，它们之间呈现不同的正负相关性，丰水期和平水期的功能微生物菌群结构差异很大。本研究为利用微生物进行重金属污染水体的治理储备了微生物资源，为实现国家“美丽乡村”的建设目标提供一定的参考价值。

Abstract:

[Background] Research on the causes of the pollution in reservoir water often focuses on water eutrophication, and the changes of pH value, dissolved oxygen, ammonia nitrogen, and total bacterial count. However, a few studies on the seasonal variation pattern of heavy metal content and environmental factors and the correlation between the heavy metal content and different environmental factors are available. In addition, there is no report on the diversity of in-situ microbial populations in typical seasons. [Objective] To detect the seasonal variation of the concentration of Mn²⁺ and Fe²⁺ and different environmental factors in the bottom water of Changtan reservoir, Taizhou city, Zhejiang province, analyze their correlation, enrich functional microbial consortia at the bottom of the reservoir in normal (February) and wet (August) periods, and elucidate the difference in the species and diversity of the enriched microbial communities. [Methods] The bottom water of the reservoir was filtrated and the functional microbial consortia was enriched. The V3–V4 regions of 16S rRNA genes were sequenced and the community structure was analyzed. All tests were carried out according to the Standard Examination Methods for Drinking Water (GB5750-2006). [Results] The concentration of Mn²⁺ and Fe²⁺ in the water of Changtan reservoir changed seasonally. The concentration of Mn²⁺ and Fe²⁺ (initial 0 mg/L) in the water began to slowly increase in the spring-summer succession period every year, peaked in summer and autumn, and then decreased to below the detection limit in the late autumn and early winter. Among the detected environmental factors, the concentration of dissolved oxygen in water, ambient temperature of reservoir, and precipitation showed obvious seasonal changes. The concentration of Mn²⁺ and Fe²⁺ had a positive correlation with temperature, precipitation, and turbidity but a negative correlation with dissolved oxygen concentration, pH value, and total phosphorus concentration. In the correlation analysis, the concentration of two metal ions had the strongest correlation with dissolved oxygen concentration, followed by ambient temperature and precipitation. The species and diversity of functional microbes were significantly different between the normal and wet periods. Only Acinetobacter and Sediminibacterium were detected in the wet period, accounting for about 50% each, while the normal period was dominated by 9 genera, such as Bacillariophyta (47.62%) and Limnohabitans (9.52%). The culturable consortia from water in the normal period and wet period both can remove the Mn²⁺ in the reservoir water, and the removal rates were about 35.9% and 11.4%, separately. [Conclusion] The concentration of Mn²⁺ and Fe²⁺ in the bottom of Changtan reservoir changes seasonally with different environmental factors, and the concentration of Mn²⁺ and Fe²⁺ shows different correlation with different environmental factors. The structures of the two functional microbial communities enriched in wet and normal periods are different. This study provides microbial resources for the treatment of heavy metal-polluted water by microorganisms, and has a certain reference value for realizing the goal of “beautiful countryside” in China.