This bacterium used to be known as Serratia liquefaciens. This small, straight Gram negative rod is motile by peritrichous flagella. Some strains produce gas from glucose. Growth is at 35-37 C. Once thought to be harmless, it is now known to be an opportunistic pathogen. It can be isolated from many natural environments, from plant roots to soil to water. Most likely, it is a secondary invader of infections.