Microbial Biomarker Fatty Acid Composition in Coastal Sediments

沿岸海底堆積物中の微生物現存量と微生物の群集構造を明らかにするために堆積物中のリン脂質の脂肪酸組成を解析した。その結果、33種の脂肪酸が検出され、それらの中には多くの細菌指標性の脂肪酸が含まれていた。微生物現存量は堆積物乾重量1gあたり1.5×10<7>～9.3×10<7>cellsと推定された。微生物バイオマーカー脂肪酸の類似度分析からは微生物の群集構造に対応する4つの異なったクラスターが認められた。沿岸堆積物中のリン脂質脂肪酸中の不飽和脂肪酸と分枝脂肪酸の分析結果から好気性細菌ならびに嫌気性細菌、特に硫酸塩還元細菌の地域的な存在特性が明らかとなった。

In the present study, the distribution of phospholipid ester-linked fatty acid composition (PLFA) in sediments were analyzed to determine the microbial biomass and microbial community structure. Thirty three fatty acids were identified in sediment samples analyzed for PLFA composition. Many fatty acids commonly considered to be indicative of bacterial contribution to sediments were identified in the study area. The calculated microbial biomass ranged from 1.5 x 10<7> to 9.3 x 10<7> cells/g dry weight of the sediment. Similarity analysis of the fatty acid composition revealed four different clusters and the possible microbial community structure is understood. The aerobic and anaerobic bacteria especially sulphate reducing bacteria are commonly distributed in the coastal sediment as evidenced by the relative proportion of unsaturated fatty acids and branched fatty acids respectively in total PLFA of sediments which are characteristic fatty acids of these bacteria.