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 <i>Pantoea</i>, and strain RHCKP32^T was most closely related to <i>Pantoea deleyi</i> LMG 24200^T, while strain RRHST58^T showed the closest relationship to <i>Pantoea septica</i> 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 <i> ω</i>7<i>c</i> and/or C_16:1 <i> ω</i>6<i>c</i>) and summed feature 8 (C_18:1 <i> ω</i>7<i>c</i> and/or C_18:1 <i> ω</i>6<i>c</i>) 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 <i>Pantoea</i>, for which the names <i>Pantoea phosphatilytica</i> sp. nov. and <i>Pantoea phyllosphaerae</i> 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.