Identification and characterization of Enterococcus species isolated from forage crops and their influence on silage fermentation

Abstract

Forty-eight strains of lactic acid bacteria were isolated from forage crops, and their identification, characterization and influence on silage fermentation were studied. All isolates were Gram-positive, short-chain-forming, catalase-negative, and facultatively anaerobic cocci that did not produce gas from glucose, only formed L-lactic acid, and were able to grow at pH 9.6%, in 6.5% NaCl, or with 40% bile, but not below pH 4.5. These isolates were commonly isolated from forage crops, and they were divided into four groups (A, B, C, and D) according to sugar fermentation characteristics. Selected strains of FA 5, FA 27, FA 45, and FA 57 were identified as Enterococcus hirae, E. faecalis, E. casseliflavus, and E. mundtii, respectively, on the basis of DNA-DNA homology, Strains FA 5, FA 27, FA 45, and FA 57 and two strains from commercial inoculants, LC 10 (Lactobacillus casei) and LP 15 (L. plantarum), were used as additives to alfalfa and guinea grass silages. Alphalfa and guinea grass silages inoculated with LC 10, LP 15, FA 5 + LC 10, and FA 5 + LP 15-treatments in alfalfa and guinea grass silages had significantly lower pH values, contents of butyric acid and ammonia nitrogen, gas production, and dry matter losses compared with the control silage after 60 d of fermentation. However, the E. hirae FA 5, E. faecalis FA 27, E. casseliflavus FA 45, and E. mundtii FA 57-inoculated silages gave similar values to the control in both types of silage. The FA 27 + LC 10 and FA 27 + LP 15-inoculated silages did not differ in fermentation quality from LC 10 and LP 15-inoculated silages alone. The results confirmed that Enterococcus species were not able to improve silage quality.