Dynamics of bacterial community in solid-state fermented feed revealed by 16S rRNA

Aims: The aim of the present study was to monitor the changes in the composition of microbiota in solid-state fermented feed and to evaluate their biosafety. Methods and Results: In the solid-state fermentation, six probiotic bacteria strains were used as inoculum and soybean meal were used as carbohydrate source. At 0, 1, 2, 3, 5, 7, 10 and 15 days, samples were collected for further analysis. Denaturing gradient gel electrophoresis (DGGE) analysis showed that Bifidobacterium bifidum and Bacillus licheniformis were always present throughout the fermentation. Bifidobacterium bifidum, Enterococcus faecalis and Lactobacillus acidophilum were dominant throughout the entire fermentation as monitored by Lactobacillus-specific PCR-DGGE. Probiotics supplementation could reduce the levels of the pathogenic bacteria such as Staphylococcus aureus and enterotoxigenic Escherichia coli (ETEC) by species-specific real-time PCR. And Salmonella spp. was not detected throughout the entire fermentation. Conclusions: Probiotics supplemented are always dominant throughout the whole period of solid-state fermentation and effective in preventing the growth of pathogens. Significance and Impact of the Study: Based on the results, the high quality, stable solid-state fermented feed could be produced and applied in the pigs to improve the animal performances.