Microbial Cycling of Methanethiol.

Methanethiol (MT) is an organic sulfur compound with a strong and disagreeable odour. It has biogeochemical relevance as an important compound in the global sulfur cycle, where it is produced as a reactive intermediate in a number of different pathways for synthesis and degradation of other globally significant sulfur compounds such as dimethylsulfoniopropionate, dimethylsulfide and methionine. With its low odour threshold and unpleasant smell, MT can be a significant cause of malodour originating from animal husbandry, composting, landfill operations, and wastewater treatment and is also associated with faeces, flatus and oral malodour (halitosis). A diverse range of microorganisms drives the production and degradation of MT, including its aerobic and anaerobic metabolism. MT producing and degrading organisms are known to be present in terrestrial, freshwater and marine environments but may also be important in association with plant and animal (including human) hosts. This chapter considers the role of MT as an intermediate of the global sulfur cycle and discusses current knowledge of microbial pathways of MT production and degradation.