The Bradyrhizobiaceae are a family of bacteria, with ten genera. They include plant-associated bacteria such as Bradyrhizobium

Bradyrhizobium

Bradyrhizobium is a genus of Gram-negative soil bacteria, many of which fix nitrogen. Nitrogen fixation is an important part of the nitrogen cycle. Plants cannot use atmospheric nitrogen they must use nitrogen compounds such as nitrates....

, a genus of rhizobia

Rhizobia

Rhizobia are soil bacteria that fix nitrogen after becoming established inside root nodules of legumes . Rhizobia require a plant host; they cannot independently fix nitrogen...

 associated with some legumes. It also contains animal-associated bacteria such as Afipia felis, formerly thought to cause cat-scratch disease

Cat Scratch Fever

Cat Scratch Fever is an album by Ted Nugent released in 1977, as well as the name of the album's title song. "Death By Misadventure" recounts the death of Brian Jones of the Rolling Stones. Guitarist Derek St. Holmes came back during this album after he left...

. Others are free-living, such as Rhodopseudomonas, a purple bacterium

Purple bacteria

Purple bacteria or purple photosynthetic bacteria are proteobacteria that are phototrophic, that is capable of producing energy through photosynthesis...

 found in marine water and soils. The strain

Strain (biology)

In biology, a strain is a low-level taxonomic rank used in three related ways.-Microbiology and virology:A strain is a genetic variant or subtype of a micro-organism . For example, a "flu strain" is a certain biological form of the influenza or "flu" virus...

 Rhodopseudomonas palustris DX-1 can generate an electric current

Electric current

Electric current is a flow of electric charge through a medium.This charge is typically carried by moving electrons in a conductor such as wire...

 with no hydrogen

Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the symbol H. With an average atomic weight of , hydrogen is the lightest and most abundant chemical element, constituting roughly 75% of the Universe's chemical elemental mass. Stars in the main sequence are mainly...

 production, a trait that is being explored in the development of the microbial fuel cell

Microbial fuel cell

A microbial fuel cell or biological fuel cell is a bio-electrochemical system that drives a current by mimicking bacterial interactions found in nature....

.