RESUMEN
OBJECTIVE: To investigate the influence of isolated predominant aerobic bacteria on daidzein biotransformation capacity by co-culture with daidzein biotransforming bacteria. METHODS: Predominant aerobic bacteria were isolated from diluted feces solutions of different healthy animals, including ICR mice, Luhua chicken, Landrace pigs and Rex rabbits. Daidzein biotransforming bacteria were anaerobically co-cultured with the isolated predominant aerobic bacteria and the cultural broth was extracted and detected by high performance liquid chromatography (HPLC). RESULTS: Twenty two predominant aerobic bacteria were isolated from the four different healthy animals mentioned above. Based on the analyses of 16S rRNA gene sequences, morphology study and relative biophysico-biochemical characteristics, all 22 isolates belong to the 5 genera, i. e. Escherichia (10) , Proteus (5) , Enterococcus (4), Bacillus (2) and Pseudomonas (1). Co-culture between predominant aerobic bacteria and daidzein biotransforming bacteria was carried out under anaerobic conditions. The results showed that the biotransformation capacity was totally lost when different daidzein biotransforming bacterium was co-cultured with either Bacillus cereus ( R1 ) or Pseudomonas aerginosa (R5) and continuously inoculated for 2 or 3 passages. However, no obvious influence was observed when daidzein biotransforming bacteria were co-cultured with all the other isolated predominant aerobic bacteria except R1 and R5. In addition, when strain R1 and R5 was co-cultured with the intestinal microflora of the ICR mice anaerobically and continuously inoculated for 5 passages, about 90% of the co-cultures totally lost the activity to convert daidzein to equol effectively. CONCLUSION: Different predominant aerobic bacteria showed different influence on daidzein biotransformation capacity after being co-cultured with different daidzein biotransforming bacteria. Among all the isolated predominant aerobic bacteria used for co-culture, both Bacillus cereus ( R1) and Pseudomonas aerginosa (R5) were detected significant inhibition on biotransformation activity of different daidzein biotransforming bacteria.