A Gram-negative, anaerobic photoautotroph, nonmotile, oval bacterium possessing gas vesicles and having no prosthecae, designated as V1, was isolated from the South China Sea coastal zone. It had chlorosomes as photosynthetic structures, and bacteriochlorophyll c as the major photosynthetic pigment. The strain was found to grow at 20-35 °C, pH 6.3-8.0 (optimum, pH 7.1) and with 0.7-5.8% (w/v) NaCl (optimum, 1-1.8%). In the presence of sulfide and bicarbonate, acetate, and fructose promoted growth. The DNA G+C content was 47 mol%. While the new isolate belonged to the Chlorobiaceae genus Prosthecochloris, it exhibited low similarity of the 16S rRNA gene sequences (96.21-96.78%) to other members of this genus. Comparison of the genome nucleotide sequences of strain V1 revealed that the new isolate was remote from the Chlorobiaceae type strains both in dDDH (16.8-18.9%) and in ANI (75.2-77.8%). We propose to assign the isolate to a new species, Prosthecochloris marina sp. nov., with the type strain V1T ( = VKM-3301T = KCTC 15824T).
Keywords: Anaerobic photoautotroph; Chlorosomes; Green sulfur bacteria; Prosthecochloris marina.