Two novel diazotrophic Paenibacillaceae bacteria, Gorillibacterium terrae sp. nov. and Oryzibacillus soli gen. nov., sp. nov., isolated from rice fields

Two novel aerobic, Gram-stain-positive, endospore-forming and short rod-shaped bacterial strains, designated as sgz500922T and sgz5001074T, were isolated from paddy soils in Fujian, PR China. The taxonomic position of two strains was determined using polyphasic taxonomy and phylogenomic analysis. Phylogenetic analysis and 16S rRNA gene sequence comparisons revealed that strains sgz500922T and sgz5001074T formed a distinct clade with Gorillibacterium massiliense G5T and shared sequence similarities of 96.3 and 93.5%, respectively. The average nucleotide identity value between the two strains and their closest reference strain was 73.1 and 72.3%, below the species threshold value of 95.0-96.0%, while the average amino acid identity values between sgz5001074T and G. massiliense and Paenibacillus contaminans were 62.4 and 63.2%, respectively. Optimal growth conditions of strains sgz500922T and sgz5001074T were pH 7.0 and 30 °C on Reasoner's 2A agar. Major fatty acids of sgz500922T and sgz5001074T were anteiso-C15:0 and C16:0. The main polar lipids included diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. Both strains contained nitrogenase core gene nifHDK in their genomes, and nitrogenase and total nitrogen accumulation estimated their nitrogen-fixing ability. According to the phenotypic, genotypic and phylogenetic data, strains sgz500922T and sgz5001074T represent two novel species of the family Paenibacillaceae, for which the names Gorillibacterium terrae sp. nov. and Oryzibacillus soli gen. nov., sp. nov., respectively, were proposed (sgz500922T=MCCC 1K09374T=KCTC 43730T, sgz5001074T (=MCCC 1K09398T=KCTC 43742T).