Paracoccus

Paracoccus is a genus of Gram-negative, non-spore-forming bacteria within the Alphaproteobacteria. Members are typically coccoid to short rod-shaped and are generally facultatively anaerobic chemoorganotrophs, capable of growing with or without oxygen depending on the available electron acceptors. A prominent feature of many species is the ability to perform denitrification, reducing nitrate to nitrogen gas in the absence of oxygen.

Metabolism and versatility: They can utilize a broad range of organic substrates, including carbohydrates and carboxylic acids. Denitrification and respiratory versatility make Paracoccus species notable models for studying bacterial respiration and nitrogen cycling. Some species have been investigated for potential in bioremediation and wastewater treatment due to their ability to operate under microaerophilic conditions.

Habitat and ecology: Paracoccus species are found in diverse environments such as soil, freshwater, marine systems, and activated sludge. They can be isolated from clinical specimens on occasion, and certain species, such as Paracoccus yeei, have been reported as opportunistic pathogens.

Genomics and model organism: Paracoccus denitrificans is the best-known member and has served as a model organism for exploring denitrification and respiratory chains. Its genome and physiology have been extensively characterized.

Taxonomy: The genus is classified within the Alphaproteobacteria, with multiple species described. The most widely cited include Paracoccus denitrificans and Paracoccus yeei.