Gram-positive bacteria are characterized by having a thick peptidoglycan cell wall measuring about 20 to 80 nm. They are mainly non-pathogenic and reside in the mucous membranes such as upper respiratory tract, mouth, skin, intestine and vagina in humans. Some species of gram-positive bacteria are used in the industrial production of amino acids, enzymes, and nucleotides. A few other species are involved in degradation of hydrocarbons, bioconversion of steroids, and cheese aging.