Comparative Genome Analyses Reveal the Genomic Traits and Host Plant Adaptations of Flavobacterium akiainvivens IK-1T

The genus Flavobacterium contains a large group of commensal bacteria identified in diverse terrestrial and aquatic habitats. We compared the genome of a new species Flavobacterium akiainvivens IK-1(T) to public available genomes of Flavobacterium species to reveal the genomic traits and ecological roles of IK-1(T). Principle component analysis (PCA) of carbohydrate-active enzyme classes suggests that IK-1(T) belongs to a terrestrial clade of Flavobacterium. In addition, type 2 and type 9 secretion systems involved in bacteria-environment interactions were identified in the IK-1(T) genome. The IK-1(T) genome encodes eukaryotic-like domain containing proteins including ankyrin repeats, von Willebrand factor type A domain, and major royal jelly proteins, suggesting that IK-1(T) may alter plant host physiology by secreting eukaryotic-like proteins that mimic host proteins. A novel two-component system FaRpfC-FaYpdB was identified in the IK-1(T) genome, which may mediate quorum sensing to regulate global gene expressions. Our findings suggest that comparative genome analyses of Flavobacterium spp. reveal that IK-1(T) has adapted to a terrestrial niche. Further functional characterizations of IK-1(T) secreted proteins and their regulation systems will shed light on molecular basis of bacteria-plant interactions in environments.