Luteibacter sahnii sp. nov., A Novel Yellow-Colored Xanthomonadin Pigment Producing Probiotic Bacterium from Healthy Rice Seed Microbiome.

Abstract

To explore the rice seed microbiome, our objective was to isolate novel strains of Xanthomonas, a plant-associated bacterium with diverse lifestyles. Four isolates, anticipated to be Xanthomonas based on morphological features of yellow colonies, were obtained from healthy rice seeds. Phylo-taxono-genomic analysis revealed that these isolates formed monophyletic lineages belonging to a novel species within the genus Luteibacter. Pairwise ortho Average Nucleotide Identity and digital DNA-DNA hybridization confirmed their distinct species status. We propose Luteibacter sahnii sp. nov. as a novel species, with PPL193^T = MTCC 13290^T = ICMP 24807^T = CFBP 9144^T as the type strain and PPL201, PPL552, and PPL554 as other constituent members. The fatty acid profile of the type strain is dominated by branched fatty acids like Iso-C_15:0, consistent with other members of the genus. The novel species displays non-pathogenic attributes and exhibits plant probiotic properties, protecting rice plants from the leaf blight pathogen X. oryzae pv. oryzae. Production of Indole-3-Acetic Acid (IAA) and genomic regions encoding anti-microbial peptides emphasize its potential contributions to plant hosts. This study underscores the importance of employing a combination of phenotypic and genotypic methods in culturomics to enhance our understanding of rice seed microbiome diversity.