Characterization and identification of ferulic acid esterase-producing Lactobacillus species isolated from Elymus nutans silage and their application in ensiled alfalfa.

AIMS

Ferulic acid esterase (FAE)-producing Lactobacillus species isolated from ensiled Elymus nutans growing on the Qinghai-Tibetan plateau were characterized, and effects of their application to the alfalfa ensiling process and the evidence to synergic effect between cellulase and FAE were investigated.

METHODS AND RESULTS

The results of 16S rRNA gene sequence and species-specific polymerase chain reaction amplification showed that two screened strains with high FAE activity were Lactobacillus plantarum A1 (LP) and L. brevis A3 (LBr). The optimum temperature and pH for the LP and LBr was 37°C and 6·4 respectively. The FAE exhibited a good stability at temperatures between 25 and 50°C and at pH values of 5·0-7·0. The two strains and a commercial cellulase (CE) were applied as additives to alfalfa silage. After 60 days of ensiling, the lactic acid in the control and CE groups were significantly lower than those of the other treatment groups. The neutral detergent fibre and acid detergent fibre contents in the LP group were significantly lower than those observed in the other groups. At the same time, the combination of CE and FAE-producing lactic acid bacteria synergistically improved the fermentation quality of the silage.

CONCLUSIONS

The addition of the FAE-producing strain of L. plantarum A1 to alfalfa silage improved its fermentation quality, and reduced the fibre content of the silage.

SIGNIFICANCE AND IMPACT OF THE STUDY

The screened homo-fermentative and FAE-producing strain of L. plantarum A1 could be a candidate strain in improving fermentation quality and fibre digestibility of ensiled forages.