微生物硫代谢及其驱动下建立的生物生态关系

硫在环境中广泛存在，是生物细胞的主要构成元素，微生物、动物和植物的硫基础代谢途径之间存在着广泛联系。本文以微生物硫代谢为主线，全面总结了硫在3类生物中的4条主要代谢途径，并重点阐明了其共性、区别及联系。微生物参与了所有硫的主要代谢，是驱动硫生物循环的主要动力。微生物异化硫还原降低了环境中甲烷的挥发，微生物、植物实施的同化性硫还原为动物提供了大量有机硫源，而植物、动物则选择性地缺少了异化或同化硫还原；硫氧化在3种生物中普遍存在且路线相似，其中，硫转移酶对氧化产物的多样化起到了重要的调节功能；发生在植物中的硫矿化尚不太清楚，而微生物、动物的硫矿化为植物硫同化提供了新的无机硫底物。自然界中，肠道微生物和宿主动物、根际微生物与植物根、动植物腐败后微生物的矿化、环境中微生物的氧化和还原等依托硫的代谢建立的生态关系，极大程度促进了硫元素的生物地球化学循环。

Microbial sulfur metabolism and the bioecological relationships driven by sulfur metabolism

Sulfur, an essential component of all living cells, is ubiquitous in the nature. Sulfur metabolic pathways in microorganisms, animals, and plants demonstrate various relationships. Based on microbial sulfur metabolism, this paper summarized four main metabolic pathways of sulfur in microorganisms, animals, and plants, and highlighted the similarities, differences, and relationships. Microorganisms, the major driving force of biological sulfur cycle, participate in all the main metabolic pathways of sulfur. The dissimilatory sulfur reduction by microorganisms reduces the volatilization of methane in the environment. The assimilatory sulfur reduction by microorganisms or plants yields abundant organic sulfur sources for animals, while plants and animals lack the function of dissimilatory or assimilatory sulfur reduction. Sulfur oxidation occurs in all the three kinds of organisms with similar pathways, in which sulfur transferase diversifies the oxidation products. Sulfur mineralization in plants is still unclear, but the mineralization in animals or microorganisms enables additional inorganic sulfur substrate for sulfur assimilation in plants. In the nature, the sulfur metabolism-based ecological relationships, such as the relationships between intestinal microorganisms and host animals and between rhizosphere microorganisms and plant roots, microbial mineralization of decayed animals and plants, and microbial oxidation and reduction of sulfur, significantly enhance the biogeochemical cycling of sulfur.