Pantoea graminicola sp. nov., a Gram-negative bacterium isolated from sweet corn (Zea mays L.) in the USA

In 2024, bacterial strains KXB24, KXB25 and KXB45 were isolated from sweet corn (<i>Zea mays</i> L.) plants exhibiting foliar chlorosis and streaking, typical symptoms of bacterial infection, in the Everglades Agricultural Area in Florida, USA. A polyphasic taxonomic study was conducted on these strains. Phylogenetic analysis of 16S rRNA gene sequences, whole-genome comparisons and biochemical characterization confirmed that the isolates belong to the <i>Pantoea</i> genus. The Biolog Gen III MicroPlate system identified substrate utilization profiles that were unique to these strains, distinguishing them from closely related <i>Pantoea</i> species. The strain KXB24 showed positive utilization of d-serine, γ-amino-butyric acid, citric acid and other compounds. On nutrient agar, KXB24, colonies are circular, smooth, convex and yellow and do not produce fluorescent pigment on King's medium B. The DNA G+C content of KXB24 was determined to be 57.0 mol%. Based on phenotypic distinctions, phylogenomics evidence, average nucleotide identity values below 94.26% and digital DNA-DNA hybridization values below 57.9% when compared to type strains of recognized <i>Pantoea</i> species, we propose <i>Pantoea graminicola</i> sp. nov., with KXB24^T (=NCPPB 4802^T=LMG 33887^T) as the type strain. This discovery enriches the current understanding of <i>Pantoea</i> species and calls for further research into the potential role of <i>P. graminicola</i> in sweet corn disease aetiology and its broader agricultural impacts.