If motile they have peritrichous flagellae. They include aerobes, facultative anaerobes, and strict anaerobes and are generally nonhalophylic with a wide growth range depending on the group. Many will grow on most simple bacteriological media. A variety of biochemical activities are noted in this family, including fermentative, proteolytic activities and the ability to grow on minimal media.
Some species can fix nitrogen.
A number of species are also characterised by producing specific toxins. Bacillus is the type genus. The two main genera Bacillus and Clostridium are distiguished by the former being aerobic, while the latter is anaerobic. Most of these include a wide variety of species. This is characteristic of the Bacillus and related groups.