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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 V1 T ( = VKM-3301 T  = KCTC 15824 T ).

This is the comparative investigation of the composition of phototrophic microbial mats developing in sulfide-rich saline Chokrak springs with outflow at the shore of the hypersaline lake Chokrak by means of next-generation sequencing. The springs are characterized by low temperature (~ 15 °C), near-neutral pH (6.7-8.5), and high-sulfide content. In the species composition the benthic microbial communities of Chokrak springs are similar to microbial mats of marine supralittoral and lagoons. Our results showed that salinity limitation had a significant effect on the species composition of benthic microbial communities developing at the outflow of the Chokrak springs. Predominant oxygenic phototrophs belonged to the genera Phormidium, Lyngbya, Leptolyngbya, Geitlerinema, and Arthrospira. Anoxygenic phototrophic bacteria were represented by halophilic green sulfur bacteria Prosthecochloris spp., halotolerant Chlorobaculum sp., as well as marine and extremely halophilic purple bacteria Roseospira, Rhodovibrio, and Halochromatium. Monoculture of a new species of halotolerant anoxygenic filamentous phototrophic bacteria was isolated.