Serratia oryzae sp. nov., isolated from rice stems

Area of Science:

• Microbiology
• Bacteriology
• Plant-Bacterial Interactions

Background:

• Endophytic bacteria reside within plant tissues, playing diverse roles in plant health and microbial ecology.
• Accurate taxonomic classification of novel bacterial isolates is crucial for understanding their ecological roles and potential applications.
• Previous studies have identified bacteria from rice, but the specific taxonomic placement of novel endophytes requires detailed investigation.

Purpose of the Study:

• To taxonomically characterize a novel endophytic bacterium, strain J11-6T, isolated from rice stems.
• To determine the phylogenetic and genotypic relationship of strain J11-6T to known bacterial species.
• To propose a new species designation for strain J11-6T based on comprehensive analysis.

Main Methods:

• Polyphasic taxonomic approach including phenotypic characterization (Gram staining, motility, shape, oxygen requirements).
• Phylogenetic analysis using 16S rRNA gene sequences and multilocus sequence analysis (MLSA) of concatenated housekeeping genes (atpD, gyrB, rpoB, infB).
• Determination of DNA G+C content and DNA-DNA relatedness with closely related type strains.

Main Results:

• Strain J11-6T is a Gram-negative, facultatively anaerobic, motile rod.
• Phylogenetic analyses indicated J11-6T belongs to the genus Serratia, closely related to Serratia fonticola and Serratia aquatilis, but distinct from Rahnella.
• Low DNA-DNA relatedness values (17.4% with Rahnella aquatilis, 29.2% with S. fonticola) confirmed its novelty.

Conclusions:

• Strain J11-6T represents a distinct lineage within the genus Serratia.
• Based on genotypic and phenotypic data, strain J11-6T is proposed as a novel species, Serratia oryzae sp. nov.
• This finding expands the known diversity of endophytic bacteria associated with rice.