Isolation and identification of forage microbial community and its effect on the fermentation quality of Pleurotus eryngii substrate

Abstract:

[Objective] This study was designed to screen the functional microbial strains suitable for the Pleurotus eryngii substrate fermentation, so as to improve its feed quality.[Methods] First, to choose suitable strains, which may have strong cellulase, ligninase and antibacterial activities. We used sifting mediums combined with the cellulase, ligninase and antibacterial activities tests. After that, we identified the species of selected strains according to their 16S rRNA (bacteria) and 18S rDNA (fungi) gene sequence analyses. Then, compound microbial inoculants were generated by mixing isovolumetric microbial solutions of each strain and used for the solid fermentation of Pleurotus eryngii substrate.[Results] We successfully acquired and identified 6 strains. Bacillus tequilensis strain P11, Pichia fermentans strain R8 and Kluyveromyces marxianus strain MU5 showed higher cellulase activity. Bacillus amyloliquefaciens subsp. and Plantarum strain MU7 showed higher ligninase activity, and Weissella paramesenteroides strain R4 and Pediococcus acidilactici strain R9 showed higher antibacterial activity. Once they were mixed and used to ferment Pleurotus eryngii substrate for 7 days, all the main indexes tested met the optimal criteria and remained stable. Compared with the EM solution fermented Pleurotus eryngii substrate, the neutral detergent fiber and acidic detergent fiber of the compound agent fermented Pleurotus eryngii substrate were significantly decreased by 19.6% and 21.44% respectively (P<0.05). The content of crude protein, crude ash and ether extract increased by 10.44%, 5.26% and 123.53% respectively (P<0.05).[Conclusion] We successfully obtained six strains, the mixture of them used to ferment the Pleurotus eryngii substrate can significantly enhance its feed quality.