RHABDOCHROMATIUM MARINUM GEN NOM REV, SP-NOV, A PURPLE SULFUR BACTERIUM FROM A SALT-MARSH MICROBIAL MAT

A new purple sulfur bacterium was isolated in pure culture (strain 831 5) from a laminated microbial mat at Great Sippewissett Salt Marsh, Ca pe God, Mass., USA. Single cells were large rods, 10-20 times longer t han wide, and predominantly straight with slightly conical ends. Cells were motile by polarly inserted flagellar tufts. Intracellular photos ynthetic membranes were of the vesicular-type. Photosynthetic pigments were bacteriochlorophyll alpha and the carotenoids lycopene, rhodovib rin, anhydrorhodovibrin, and rhodopin. The new bacterium was strictly anaerobic and obligately phototrophic. Hydrogen, hydrogen sulfide, ele mental sulfur, and thiosulfate were used as electron donors for photoa utotrophic growth. In sulfide-reduced, bicarbonate-containing media, a cetate, propionate, and pyruvate were photoassimilated. Growth factors were not required. Optimum growth rates were obtained at pH 7.3, 30 d egrees C, a salinity of 1.5-5.0% NaCl, and a light intensity of about 500 1x (tungsten lamp). The DNA base composition of strain 8315 was 60 .4 mol% G+C. Comparison of 16S rDNA oligonucleotide catalogue data sho wed that the new bacterium must be considered a new genus of the Chrom atiaceae. The name Rhabdochromatium is revived, and the new species Rh abdochromatium marinum sp. nov. is described.