Bacterial populations associated with rice seed in the tropical environment

During the 1995 wet season, harvested rice seed was collected from farmers' fields at different locations in Iloilo, Philippines. Bacterial isolations from crushed seed yielded 428 isolates. The isolates were characterized by BOX-polymerase chain reaction fingerprinting of total genomic DNA and repr esented 151 fingerprint types (FPT). Most FPTs were found on a single occas ion, although matching fingerprints for isolates from different samples als o were found. Identifications were made by cellular fatty acid methyl ester analysis and additional use of Biolog GN/GP MicroPlates and API 20E/50CHE systems. The predominant bacteria were Enterobacteriaceae (25%), Bacillus s pp. (22%), and Pseudomonas spp. (14%). Other bacteria regularly present wer e identified as Xanthomonas spp., Cellulomonas flavigena, and Clavibacter m ichiganense. Of the total number of isolated bacteria, 4% exhibited in vitr o antifungal activity against Rhizoctonia solani or Pyricularia grisea. Two percent of isolates were pathogens identified as Burkholderia glumae and B urkholderia gladioli. Five percent of isolates induced sheath necrosis on o nly 50 to 90% of inoculated plants and were related to Bacillus pumilus, Pa enibacillus spp., Pseudomonas spp., and Pantoea spp.