Aerobic microbial oxidation of sulphide and methane

In doing so, they deposit sulphur granules in the cells external to the cytoplasmic membrane. They can also use these sulphur granules as a storage product, oxidising them further (to sulphate) when sulphide is limiting (Ehrlich, 1990). 

Also common at seeps are the S-oxidising symbionts living in vestimentif-eran tube worms and various clams (Aharon, 2000 Tunnicliffe etal., 2003). These symbionts generally fix C02 by the Calvin-Benson cycle and share some of the carbon they assimilate with their host. 

Methanotrophs oxidise methane, with 02 as the terminal electron acceptor, e.g. 

They live either as symbionts in mussels or as free-living aggregates at seeps (see references in Aharon, 2000). Although methane is their main metabolite, some methanotrophs may also assimilate up to 30% of their carbon as C02 (Ehrlich, 1990). 

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