Influence Of Predominant Aerobic Bacteria Isolated From Different Healthy Animals On Daidzein Biotransforming Capacity By Co-culture With Different Daidzein Biotransforming Bacteria

Daidzein is one of the main component of isoflavones, which is capable of being biotransformed into different metabolites, including dihydrodaidzein, equol and O-desmethylangolensin by gastrointestinal microflora after being absorebed by organisms.Under aerobic conditions, 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). Twenty two predominant aerobic bacteria were isolated from the four different healthy animals mentioned above. Based on the the analyses of 16S rRNA gene sequences, morphology study and relative biophysico-biochemical characteristics, all the 22 isolates belong to the five genus, i.e. Escherichia (10), Proteus (5), Enterococcus (4), Bacillus (2) and Pseudomonas (1). Different predominant aerobic bacteria were chosen randomly from different genus and co-cultured with different daidzein biotransforming bacteria, respectively. The results showed that except strain R1 and R5 isolated from Rex rabbits feces, all the other predominant aerobic bacteria chosen for co-culture were not detected any obvious influence on the daidzein biotransforming bacteria. However, the biotransformation capacity was totally lost when daidzein biotransforming bacteria were co-cultured with either R1 or R5 and continuously inoculated for 2 or 3 passages. 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.Predominant aerobic bacteria from different healthy animals were of similarity and difference. In comparison with ICR mice, Luhua chicken and Landrace pigs, the predominant aerobic bacteria isolated from Rex rabbits showed a large obvious diversity. Further more, 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.