Isolating and evaluating lactic acid bacteria strains for effectiveness on silage quality at low temperatures on the Tibetan Plateau

Abstract BackgroundLactic acid bacteria with natural, effective antibacterial activity, safe and reliable characteristic, gradually become one of the key technologies in food fermentation applications, food preservation and other fields. In this study, 112 presumptive lactic acid bacteria isolated from Tibetan Qula, a fermented yak cheese popular in the Tibetan plateau, were screened for potential probiotic microorganism with antimicrobial activity.Results12 lactic acid bacteria were found to have antibacterial activity, and strain QZ50 in particular showed broad-spectrum inhibition against pathogenic bacteria, which retained its antibacterial activity after sequential removal of acids and hydrogen peroxide, indicating the production of a broad-spectrum bacteriocin that could inhibite Micrococcus luteus ATCC 28001, Staphylococcus aureus ATCC 26003, Bacillus subtilis ATCC 63501, Escherichia coli ATCC 30105, Pseudomonas aeruginosa ATCC 10104, and Salmonella enterica ATCC 50094. Strain QZ50 was identified as Lactobacillus plantarum based on physicochemical characteristics and 16S rDNA sequencing. And the optimum production conditions were evaluated to obtain the highest yield of plantaricin QZ50. The optimum medium, temperature, initial pH, and inoculum amount for plantaricin QZ50 production were Man, Rogosa, and Sharpe (MRS), 30°C, 6.5, and 3%, respectively. In addition, different C source, N source and stimulating factors in medium show significant effects on plantaricin QZ50 production (P ＜ 0.05). The optimum C and N source were respectively glucose and yeast extract, and 2% Tween 80 contributed highest production of plantaricin QZ50. Plantaricin QZ50 exhibited strong heat stability and remained activity at pH 2.0–8.0. In addition, plantaricin QZ50 was inactivated by pepsin, proteinase K, trypsin, papain, and chymotrypsin.ConclusionsSome strains of Lactobacillus isolated from the Qula in the Tibetan plateau have good antibacterial activity which could be considered as potential probiotic. The strain of Lactobacillus plantarum QZ50, with a broad-spectrum, stable, safe, and natural antibiotic, has potential applications as a food biopreservative.

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Effects of fibrolytic enzymes, molasses and lactic acid bacteria on fermentation quality of mixed silage of corn and hulless-barely straw in the Tibetan Plateau

Grassland Science ◽

10.1111/grs.12060 ◽

2014 ◽

Vol 60 (4) ◽

pp. 240-246 ◽

Cited By ~ 20

Author(s):

Gang Guo ◽

Xianjun Yuan ◽

Longxin Li ◽

Aiyou Wen ◽

Tao Shao

Keyword(s):

Lactic Acid ◽

Tibetan Plateau ◽

Lactic Acid Bacteria ◽

The Tibetan Plateau ◽

Fibrolytic Enzymes ◽

Fermentation Quality

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Impact inoculum dosage of lactic acid bacteria on oat and wheat silage fermentation at ambient and low temperatures

Crop and Pasture Science ◽

10.1071/cp17250 ◽

2018 ◽

Vol 69 (12) ◽

pp. 1225

Author(s):

Miao Zhang ◽

Zhongfang Tan ◽

Xiaojie Wang ◽

Meiyan Cui ◽

Yanping Wang ◽

...

Keyword(s):

Lactic Acid ◽

Low Temperature ◽

Lactic Acid Bacteria ◽

Ambient Temperature ◽

Low Temperatures ◽

Raw Materials ◽

Antimicrobial Properties ◽

Alpine Regions ◽

Silage Quality

Lactic acid bacteria (LAB) can be used as silage additives to ensure rapid and vigorous fermentation at early stages of ensiling. We predicted that the optimal LAB inoculation dosage for forage at ambient temperature (15–38°C) would be different from that at cold temperature (4°C). In this study, Lactobacillus plantarum QZ227, isolated from a wheat landrace in alpine regions of Qinghai, China, and commercial L. plantarum FG1 were used as inoculum, with sterile water as control. The effects of inoculum dosage on the fermentation quality of oat (Avena sativa L. cv. Qinghai) and wheat (Triticum aestivum L. cv. Yumai No. 1) silage at ambient temperature (15–38°C) and at 4°C were investigated in laboratory experiments. Little or no improvement in silage quality occurred upon increasing the inoculum dosage at ambient temperature. By contrast, a lower pH and NH3-N content, and a higher LAB count and lactic acid content, were observed at 4°C. Furthermore, the growth of Escherichia coli was inhibited effectively at the lower temperature, and silage quality was positively correlated with increasing inoculum dosage (P<0.05). These results suggest that increasing the inoculum dosage could improve the quality of silage at lower temperatures of 4°C, whereas an appropriate dosage was a key factor for silage at ambient temperature. In this study, oat forage could be used as raw materials for ensiling only at low temperature but was not suitable for ensiling at ambient temperature without wilting due to the high moisture content (86.55%). QZ227 isolated from the roots of wheat in alpine regions displayed superior antimicrobial properties against yeast at ambient temperature and E. coli at 4°C compared with commercial strain FG1. This is the first study to explore the effects of inoculum dosage on silage quality at low temperatures, and provides a basis for low-temperature silage technologies.

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