Abstract
ObjectiveFour lactic acid bacteria (LAB) strains isolated from common vetch, tall fescue and perennial ryegrass on the Tibetan Plateau were characterized, and their effects on the fermentation quality of Italian ryegrass (Lolium multiflorum Lam.) silage were studied.MethodsThe four isolated strains and one commercial inoculant (G, Lactobacillus plantarum MTD-1) were evaluated using the acid production ability test, morphological observation, Gram staining, physiological, biochemical and acid tolerance tests. The five LAB strains were added to Italian ryegrass for ensiling at three different temperatures (10°C, 15°C, and 25°C).ResultsAll isolated strains (LCG3, LTG7, I5, and LI3) could grow at 5°C to 20°C, pH 3.0 to 8.0 and NaCl (3.0%, 6.5%). Strains LCG3, LTG7, I5, and LI3 were identified as Lactobacillus plantarum, Pediococcus acidilactici, Lactobacillus paraplantarum, and Lactobacillus casei by sequencing 16S rDNA, respectively. All LAB inoculants significantly (p<0.05) increased lactic acid (LA) contents and ratios of lactic acid to acetic acid, and reduced pH and ammonia nitrogen/total nitrogen (AN/TN) compared with uninoculated silages at various temperatures (10°C, 15°C, and 25°C). Compared to the commercial inoculant G, I5, and LI3 showed similar effects on improving the silage quality of Italian ryegrass at 10°C and 15°C, indicated by similar pH, LA content and AN/TN.ConclusionAll inoculants could improve the silage fermentation quality at various temperatures (10°C, 15°C, and 25°C). At the temperature of 10°C and 15°C, strain I5 and LI3 had similar effects with the commercial inoculant G on improving the silage quality of Italian ryegrass.
Highlights
Tibetan Plateau, located in southwest China with an average elevation of 4,000 m above sea level, is regarded as the Earth’s third pole and the highest unique territorial unit in the world
Ensiling is a major method of forage conservation, and it is based on natural fermentation in which epiphytic lactic acid bacteria (LAB) convert water-soluble carbohydrates (WSC) into lactic acid (LA) under anaerobic conditions
Strains I5 and LCG3, which belong to L. paraplantarum and L. plantarum (Table 1) respectively, showed high tolerance to low pH and temperature, which are consistent with the findings of Pang et al [15]
Summary
Tibetan Plateau, located in southwest China with an average elevation of 4,000 m above sea level, is regarded as the Earth’s third pole and the highest unique territorial unit in the world. In this distinct ecological region, the unique geographical and climatic conditions of Tibetan Plateau have contributed to the formation of specific microorganisms found in forage crops and grasses [1]. Ensiling is a major method of forage conservation, and it is based on natural fermentation in which epiphytic lactic acid bacteria (LAB) convert water-soluble carbohydrates (WSC) into lactic acid (LA) under anaerobic conditions.
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