Effect of isolated lactic acid bacteria on the quality and bacterial diversity of native grass silage.

OBJECTIVE

The objective of this study was to isolate lactic acid bacteria (LAB) from native grasses and naturally fermented silages, determine their identity, and assess their effects on silage quality and bacterial communities of the native grasses of three steppe types fermented for 60 days.

METHODS

Among the 58 isolated LAB strains, (BL1) and (BL5) were identified using 16S rRNA sequences. Both strains showed normal growth at 15- 45°C temperature, 3-6.5% NaCl concentration, and pH 4-9. Two isolated LAB strains (labeled L1 and L5) and two commercial additives ( and ; designated as LP and LB, respectively) were added individually to native grasses of three steppe types (meadow steppe, MS; typical steppe, TS; desert steppe, DS), and measured after 60 d of fermentation. The fresh material (FM) of different steppe types was treated with LAB (1 × 10 colony forming units/g fresh weight) or distilled water (control treatment [CK]).

RESULTS

Compared with CK, the LAB treatment showed favorable effects on all three steppe types, i.e., reduced pH and increased water-soluble carbohydrate content, by modulating the microbiota. The lowest pH was found in the L5 treatment of three steppe types, at the same time, the markedly ( < 0.05) elevated acetic acid (AA) concentration was detected in the L1 and LB treatment. The composition of bacterial community in native grass silage shifted from and to at the species level. The abundance of and increased significantly in L1, L5, LP, and LB treatments, respectively, compared with CK ( < 0.05).

CONCLUSION

In summary, the addition of LAB led to the shifted of microbiota and modified the quality of silage, and and improved the performance of native grass silage.