南海深海有机质的生物降解过程、机制及微生物在碳循环的作用

有机质的降解是海洋碳循环的重要环节，微生物在有机质的降解中发挥着重要作用。深海有机质大多是相对难被生物降解的有机质。本项目的总体目标是，选择相对难被生物降解的有机碳和有机氮为研究对象，分析南海深海沉积物中参与这些有机质降解的微生物种类和分泌到细胞外的水解酶的种类及其多样性，选择典型降解酶，研究其酶解这些难降解有机质的生物化学机制，揭示微生物参与的南海深海有机质水解的胞外生物学过程。对参与有机质降解的典型细菌属、种、株进行全基因组测序，通过基因组学、比较基因组学和代谢网络分析，揭示南海深海典型细菌的生命特征及细菌细胞内的有机碳、有机氮代谢的过程、机制与相互偶联。通过南海深海沉积物原位酶活性测定、原位基因表达的宏转录组学分析和实验室内典型菌株的模拟培养的基因表达与调控分析，结合生物化学机制研究，初步揭示南海深海有机碳、有机氮代谢的生物学过程、机制以及微生物在南海深海碳循环中作用。

Organic matter degradation is an essential step of oceanic carbon cycle. Microorganisms play an important role in oceanic organic matter degradation. Most organic matters in deep sea are reluctant to biodegradation. The general aim of this program is, with the organic carbon and organic nitrogen reluctant to biodegradation as objectives, to analyze the microorganisms and the extracellular hydrolytic enzymes involved in the degradation of these organic matters in the deep-sea sediments in the South China Sea. The biochemical mechanism of some typical enzymes to degrade the reluctant organic matters will be studied, and the extracellular process of microorganisms to participate in organic matter degradation in the deep sea of the South China Sea will be explored. The genomes of some typical bacterial genera, species and strains involved in organic matter degradation will be sequenced, and through analyses of genomics, comparative genomics and metabolism network, the life styles of typical bacteria and the intracellular metabolism process, mechanism and the coupling of organic carbon and organic nitrogen of these bacteria from the South China Sea will be uncovered. The enzymes activities in situ in the deep-sea sediments of the South China Sea will be measured, and mega transcriptomics in situ will be analyzed. The typical bacterial strains will be cultured in simulated deep sea conditions and gene expression and regulation of these strains will be analyzed. These studies, combined with the biochemical mechanism studies, will preliminary elucidate the bioprocess of metabolisms of organic carbon and organic nitrogen in the sediments and the roles of microorganisms in carbon cycling in the deep sea of the South China Sea.