Phylogenetic identificationI of lactic acid bacteria isolates and their effects on the fermentation quality of sweet sorghum (sorghum bicolor) silage.

AIM: to isolate, screen and identify the lactic acid bacteria (LAB) from elephant silage during the process of the fermentation and their effects on the fermentation quality of sweet sorghum silage.

METHODS AND RESULTS: The isolated strains were identified based on morphological, physiological and biochemical characteristics as well as 16S rRNA analysis. Seven LAB strains were isolated from elephant grass silage. Three strains (Pediococcus acidilactici (AZZ1), Lactobacillus plantarum subsp. Plantarum (AZZ4), Lactobacillus plantarum subsp. Argentoratensis (AZZ7) and one commercial bacteria Lactobacillus Plantarum, Ecosyl MTD/1(CB)) were chosen as additives at 6 log colony forming units (cfu)/g of fresh sweet sorghum grass in laboratory silos (680g). Silos for each treatment were opened after 5, 7, 14, 30 and 60 d, respectively.All isolates were characterized as gram-positive, catalase-negative and grow normally in 6.5% NaCl.The strains AZZ1, AZZ2, and AZZ5, were identified as Pediococcus genus while AZZ3, AZZ4, AZZ6, and AZZ7 were Lactobacillus genus.Compared to the control, all the isolatesimproved the silage quality of sweet sorghum silage, indicated by significantly (P<0.05) lower pH and ammonia nitrogen (NH3 -N) contents and undesirable microorganism counts, and higher lactic acid (LA) contents and ratios of lactic acid/acetic acid (LA/AA). During ensiling, AZZ4 performed better among of all inoculants, indicated by significantly (P<0.05) decreased on pH and ammonia-N contents and higher increased on lactic acid contents.

CONCLUSION: strain AZZ4 is recommended as starter culture for sweet sorghum.

SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first time to investigate the effects of lactic acid bacteria isolates from elephant grass silage and use them as additives, which is to find out how LAB inoculants improve the fermentation quality of sweet sorghum silage. This article is protected by copyright. All rights reserved.