Environmental distribution and genomic characteristics of Solirubrobacter, with proposal of two novel species

Solirubrobacter spp. were abundant in soil samples collected from deserts and other areas with high UV radiation. In addition, a novel Solirubrobacter species, with strain CPCC 204708 as the type, was isolated and identified from sandy soil sample collected from the Badain Jaran Desert of the Inner Mongolia autonomous region. Strain CPCC 204708 was Gram-stain positive, rod-shaped, non-motile, non-spore-forming, and grew optimally at 28-30°C, pH 7.0-8.0, and in the absence of NaCl. Analysis of the 16S rRNA gene sequence of strain CPCC 204708 showed its identity within the genus Solirubrobacter, with highest nucleotide similarities (97.4-98.2%) to other named Solirubrobacter species. Phylogenetic and genomic analyses indicated that the strain was most closely related to Solirubrobacter phytolaccae KCTC 29190, while represented a distinct species, as confirmed from physiological properties and comparison. The name Solirubrobacter deserti sp. nov. was consequently proposed, with CPCC 204708 (= DSM 105495 = NBRC 112942) as the type strain. Genomic analyses of the Solirubrobacter spp. also suggested that Solirubrobacter sp. URHD0082 represents a novel species, for which the name Candidatus "Solirubrobacter pratensis" sp. nov. was proposed. Genomic analysis of CPCC 204708 revealed the presence of genes related to its adaptation to the harsh environments of deserts and may also harbor genes functional in plant-microbe interactions. Pan-genomic analysis of available Solirubrobacter spp. confirmed the presence of many of the above genes as core components of Solirubrobacter genomes and suggests they may possess beneficial potential for their associate plant and may be important resources for bioactive compounds.