Firmicutes

This phylum of bacteria is divided into four classes.

Class Bacilli, families Bacillaceae, Listeriaceae, Staphylococcaceae, Enterococcaceae, Lactobacillaceae, Streptococcaceae

Class Clostridia, families Clostridiaceae, Eubacteriaceae, Peptococcaceae, Peptostreptococcaceae, Ruminococcaceae

Class Erysipelotrichi, family Erysipelotrichidae (genus Erysipelothrix)

Class Mollicutes, orders Acholeplasmatales and Mycoplasmatales