沉湖钻孔沉积物中微生物脂肪酸特征与意义

利用微生物脂肪酸甲酯分析技术研究了江汉平原沉湖湖心滩G1与湖岸G2两沉积柱中微生物群落结构的垂直分布特征及其环境指示意义.结果表明：微生物脂肪酸含量与特征脂肪酸分布特征在浅层（<5m）波动较大，且与深层（5~20m）差异明显；好氧细菌、一般厌氧细菌与革兰氏阳性菌占主要优势，其相对丰度高出深层约一倍.G1位点偏还原环境，其硫酸盐还原菌及其他厌氧细菌的相对丰度与环境胁迫压力（Trans/Cis）均高于G2；与溶氧相关的环境因子，如粒径、深度等是影响其微生物群落组成的关键因子.G2位点水动力条件较强，脂肪酸总量与好氧微生物的相对优势均高于G1，而深层沉积物中总氮、N/P偏低，微生物群落组成主要受碳氮营养源，特别是氮含量的影响.为评估人类活动带来的氮磷污染对湖泊深层微生物的影响提供新的认识.

Distribution and environmental significance of microbial fatty acids in borehole sediments of Chen Lake

Microbial fatty acid methyl ester analysis was used to evaluate the vertical distribution of microbial community structure and its environmental implications in sediments from the open beach borehole G1 and the shoreline borehole G2 of Chen lake, Jianghan Plain. The results showed that total microbial fatty acids (FAs) content and their distribution characteristics fluctuated greatly in the shallow layers (<5m), and significantly differed from those in the deep layers (5~20m). Aerobes, common anaerobes and Gram-positive bacteria were the dominant microbial groups, and their relative abundance in the shallow layers was almost double that in the deep layers. The relative abundance of sulfate-reducing bacteria and other anaerobic bacteria and environmental stress index (Trans/Cis) were higher in G1 than those in G2. The environmental factors related to dissolved oxygen, such as particle size and depth, were the key factors affecting the composition of microbial community. Owing to the stronger hydrodynamic conditions at G2, the total FAs and the relative dominance of aerobic microorganisms were higher than those at G1. Total nitrogen and N/P were relatively low in deep sediments, where microbial community structure was mainly affected by the carbon and nitrogen source availability, especially the nitrogen content. These findings provide new insights on the effects of anthropogenic nitrogen and phosphorus pollution on microbial community in the deep lake sediments.