Paracoccus bengalensis sp. nov., a novel sulfur-oxidizing chemolithoautotroph from the rhizospheric soil of an Indian tropical leguminous plant

Paracoccus versutus-like isolates from the rhizosphere of Clitoria ternatea, a slender leguminous herb (family—Papilionaceae), found ubiquitously in waste places and village forests of the Lower Gangetic plains of India, presented a case of graduated infraspecific variation that was capped by the identification of a new species Paracoccus bengalensis (type strain JJJT=LMG 22700T=MTCC 7003T). The diverged phenetic and genetic structure of these sulfur-oxidizing chemolithoautotrophs presented a case of apparent nonconformity of 16S rRNA gene sequence similarities with results of DNA–DNA hybridization. Despite high 16S rRNA gene sequence similarity with P. versutus one of the newly isolated strains, viz., JJJT was identified as a new species of Paracoccus by virtue of its explicitly low DNA–DNA hybridization (42–45%) with the type strain of the closest species P. versutus (ATCC 25364T), distinct G+C content (65.3 mol%), physiological and biochemical differences amounting to <60% phenetic similarity with strains of P. versutus as well as new isolates akin to the species. The newly described species also had a unique fatty acid profile that was distinguished by the absence of 18:1 ω9c, unique possession of Summed feature 3 (16:1ω7c & 15:0 iso 2-OH), 19:0 10 methyl, and a much higher concentration of 19:0 cycloω8c.