Feet bacteria. Coloured scanning electron micrograph (SEM) of bacteria cultured from between the toes of the foot. Squamous cells arethe flat areas at center. Brevibacteria are considered a major cause of foot odour because they ingest dead skin on the feet and, in the process, convert the amino acid methionine into methanethiol, which is a colorless gas with a distinctive putrid smell that has a sulfuric aroma. The dead skin that fuels this process is especially common on the soles and between the toes. The brevibacteria are also what give cheeses their characteristic smell. There are around 1000 species of bacteria from 19 phyla found on human skin. Skin flora is usually non-pathogenic, and either commensal (not harmful to their host) or mutualistic (offer a benefit). Magnification: x3000 when printed at 10cm wide.