Genome-based polyphasic characterization of paddy soil-derived Paenibacillus: proposal of four novel species with plant growth-promoting traits

Abstract Background The genus Paenibacillus is primarily inhabited in plant-associated habitats, indicating its potential for plant growth promotion in agriculture. However, the diversity and functional potential of Paenibacillus in paddy soils remains largely unexplored. Results In the present study, six strains designated sgz302190, sgz302191, sgz302164 T , sgz302114 T , sgz302115 T , and sgz302148 T were isolated from paddy soil (China) and their taxonomic positions and plant growth-promoting traits were evaluated. The 16S rRNA gene sequence similarity and phylogenetic analysis suggested they were members of the genus Paenibacillus. The optimum temperature and pH for growth of these strains ranged from 30 to 37 °C and pH 6.0–7.5. All strains contained MK-7 as the respiratory quinone and anteiso-C 15:0 as a major fatty acid. The major polar lipids present in all strains were diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine. The strains consisted of plant growth-promoting traits like increase in rice seed germination, inorganic phosphate hydrolysis, and production of siderophores and indole-3‐acetic acid. Their average nucleotide identity values were below the threshold values (95–96%) for species delineation. Conclusions Based on the analysis, strains sgz302164 T , sgz302114 T , sgz302115 T , and sgz302148 T represent four novel species of the genus Paenibacillus , for which the names are proposed as Paenibacillus azotofaciens sp. nov. (the type strain sgz302115 T = MCCC 1K09509 T = GDMCC 1.7245 T = KCTC 43798 T ), Paenibacillus rhodinus sp. nov. (the type strain sgz302114 T = MCCC 1K09531 T = GDMCC 1.7247 T = KCTC 43796 T ), Paenibacillus caliditolerans sp. nov. (the type strain sgz302148 T = MCCC 1K09519 T = GDMCC 1.7246 T = KCTC 43799 T ), and Paenibacillus phosphatilyticus sp. nov. (the type strain sgz302164 T = MCCC 1K09510 T = GDMCC 1.7244 T = KCTC 43800 T ).