Microbial sulfur metabolism and the bioecological relationships driven by sulfur metabolism

Abstract:

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.