优良乳酸菌的筛选及对苜蓿青贮发酵品质的影响

Screening of Lactic Acid Bacteria and Its Effect on Fermentation Characteristics of Alfalfa Silage

为获得有效抑制梭菌的苜蓿青贮用乳酸菌,通过抑菌活性、酸化苜蓿汁液能力及生理生化等指标,从苜蓿附生乳酸菌中筛选优良菌株,并研究其在15℃、25℃和35℃贮藏条件下对苜蓿(Medicago sativa)青贮发酵品质和微生物组成的影响。结果表明:筛选到抑菌活性、苜蓿汁液酸化能力、生长速率、温度耐受性和碳源利用等综合性能较好的菌株LP31,该菌被鉴定为植物乳杆菌(Lactobacillus plantarum)。与对照组相比,15℃、25℃和35℃贮藏下青贮56d后,植物乳杆菌处理组可有效促进乳酸发酵、抑制梭菌生长、显著改善高水分苜蓿青贮品质(P<0.05)。而对照组苜蓿青贮,除15℃贮藏条件外,均发生严重的丁酸发酵,表现为:pH值、丁酸和氨态氮含量较高以及乳酸含量和V-Score较低。综上所述,使用该筛选方法获得的优良乳酸菌有益于抑制高水分含量苜蓿青贮的丁酸发酵,可改善苜蓿青贮品质。

To obtain lactic acid bacteria that can effectively inhibit clostridia in alfalfa(Medicago sati-va)silage,excellent strains were screened from alfalfa epiphytic lactic acid bacteria through antibacterial activity test,acidification ability of alfalfa juice,and physiological and biochemical characteristics.The effects of screened lactic acid bacteria on the fermentation quality and microbial composition of alfalfa si-lage were studied at 15℃,25℃and 35℃.The results showed that LP31 identified as Lactobacillus plan-tarum was screened,which had better comprehensive performance including antibacterial activity,acidifi-cation ability of alfalfa juice,growth rate,temperature tolerance,and carbon source utilization.Compared with the control group,the L.plantarum treatment could promote lactic acid fermentation,inhibit clos-tridia growth,and significantly improve the fermentation quality of alfalfa silage with high water content after ensiling at 15℃,25℃and 35℃for 56 days(P<0.05).In the control group,severe butyric acid fermentation occurred in alfalfa silage,except for the storage condition at 15℃,which was characterized by higher pH value,higher butyric acid and ammonia nitrogen contents,and lower lactic acid content and V-Score.In conclusion,the excellent lactic acid bacteria obtained by using this screening method was ben-eficial to inhibit the butyric acid fermentation of alfalfa silage with high water content and improve the quality of alfalfa silage.