A new bacterium (nitrate-respiring, prodigiosin-producing, marine curved rod with a sheathed flagellum) has been isolated from anaerobic mud underlying a microbial meat. This brightly pigmented red bacterium, referred to as strain BV1 (Baja California vibrio, isolate 1) was taken from a closed, hypersaline basin at Laguna Figueroa (or Laguna Mormona), Baja California de Norte, Mexico. It is closely related to the recently described Beneckea gazogenes (Harwood, 1978), which was isolated from an estuarine habitat, the Sippewissett salt marsh at Woods Hole, Massachusetts, U.S.A. Strain BV1 and B-gazogenes are both oxidase positive facultative anaerobic curved rods which bear a single polar flagellum, and synthesize the red-orange tri-pyrrole pigment prodigiosin. The bacterium, which fluoresces green when excited with UV light (lambda = 455 nm), deposits pigment extracellularly in copious quantities. The extracellular pigment deposits fluoresce red-yellow. Both BV1 and B. gazogenes are able to grow utilizing xylose, cellobiose or arabinose, products of plant biosynthesis, as sole carbon sources. BV1 differs from B. gazogenes in cell size, pattern of pigment production, nutritional characteristics, the ability to perform anaerobic respiration using nitrate as a terminal electron acceptor, sensitivity to a newly discovered lytic phage and to the antibiotic vibriostat O/129.