To analyze the microflora in fermented rice bran product, bacterial colonies were grown under various conditions. Although cultivation temperature did not affect the number of bacterial colonies formed on agar plates, twice as many colonies formed under aerobic as under anaerobic conditions. All colonies appearing on the plates showed acid production. Based on 16S rRNA sequence analysis, nearly all of the bacteria in the fermented product were highly similar (>99%) to Lactobacillus johnsonii. In addition, several Bacillus cereus and unidentified Lactobacillus strains that grew only under anaerobic conditions at 30℃ were seen. Random Amplified Polymorphic DNA (RAPD)-PCR analysis showed the amplified patterns of all isolates to differ substantially from the reference strain L. johnsonii. We conclude that L. johnsonii-related strains predominate in fermented rice bran product, and that these bacteria produce lactic acid to decrease the pH of the fermented product. Several novel Lactobacillus strains may also occur in this environment.