Pantoea phosphatilytica sp. nov. and Pantoea phyllosphaerae sp. nov., two phosphate-solubilizing and siderophore-producing bacteria isolated from citrus phyllosphere

Two yellow-pigmented, Gram-stain-negative, aerobic, motile and rod-shaped bacterial strains, designated RHCKP32 T and RRHST58 T , were isolated from the citrus leaves in Renhua County, a famous planting area located in Guangdong Province, China. Phylogenomic analysis showed that they belonged to the genus Pantoea , and strain RHCKP32 T was most closely related to Pantoea deleyi LMG 24200 T , while strain RRHST58 T showed the closest relationship to Pantoea septica LMG 5345 T . The overall genomic relatedness analysis showed that strains RHCKP32 T and RRHST58 T shared 84.3‒94.6 and 89.5‒94.5% average nucleotide identity and 32.0‒58.0 and 38.5‒58.2% digital DNA–DNA hybridization with their closely related type strains, respectively, which were all below the suggested threshold values for novel species delimitation. They both took ubiquinone 8 (Q-8) as the predominant respiratory quinone and C 16:0 , C 17:0 cyclo, summed feature 2 (C 14:0 3-OH and/or iso-C 16:1 I), summed feature 3 (C 16:1 ω 7 c and/or C 16:1 ω 6 c ) and summed feature 8 (C 18:1 ω 7 c and/or C 18:1 ω 6 c ) as their major fatty acids. The genomic DNA G+C contents of strains RHCKP32 T and RRHST58 T were 57.33 and 58.77 mol%, respectively. Based on the phenotypic, phylogenetic and chemotaxonomic analyses, they should be considered as two novel species of the genus Pantoea , for which the names Pantoea phosphatilytica sp. nov. and Pantoea phyllosphaerae sp. nov. are proposed with RHCKP32 T (=GDMCC 1.2672 T =JCM 34793 T ) and RRHST58 T (=GDMCC 1.2673 T =JCM 34797 T ) as the type strains, respectively. In addition, they showed the ability to solubilize inorganic phosphates and produce siderophores, for which the maximum soluble phosphorus concentrations could reach 510.03±7.11 and 506.47±3.08 mg l −1 for strains RHCKP32 T and RRHST58 T after 5 days of inoculation in liquid National Botanical Research Institute’s (NBRIP) medium, respectively, and the corresponding relative siderophore production was 21.25±2.23 and 10.20±0.15 percent siderophore unit after 2 days of inoculation in nutrient broth, implicating they might have potential application in promoting plant growth.