青贮用乳酸菌的筛选及其生物学特性研究

Screening of lactic acid bacteria strains and their biological characteristics

【目的】筛选生长繁殖快、产酸能力强且耐酸的乳酸菌,以获得制备果渣青贮发酵剂的优良菌株。【方法】通过葡萄糖发酵产酸产气特征、产酸速率和生长曲线进行供试乳酸菌的筛选,对筛选出的优良菌株进行形态学、生理生化和分子生物学鉴定,并进一步研究其生长温度范围、酸碱耐受性、耐盐性,最后对菌株发酵液进行酸度滴定和有机酸组分分析。【结果】经筛选共获得R7、R3、Rg和Re 4株优良乳酸菌。经形态学、生理生化和16SrDNA序列分析,确定R7为植物乳杆菌(Lactobacillus plantarum),R3为戊糖乳杆菌(Lactobacillus pentosus),Rg为发酵乳杆菌(Lactobacillus fermentum),Re为鼠李糖乳杆菌(Lactobacillus rhamnosus)。4株菌均可在15~50℃生长。菌株R7生长最快,降酸能力最强,发酵液乳酸含量最高,占总酸含量的95.40%,在pH值3.0条件下可以旺盛繁殖,同时可耐受质量浓度0.08g/mL NaCl。Re、R3生长及产酸仅次于R7,酸碱耐受性较强。Rg在50℃生长良好,可耐受高温。【结论】菌株R7、Re、R3、Rg具有生长快、产酸能力强、耐酸、产乳酸含量高等优良生物学特性,可应用于果渣青贮饲料添加剂的制备。

【Objective】This study aimed to screen acid bacteria strains for pomace silage additive usage which grow fast and have strong acid production capacity and acid tolerance.【Method】The tested strains were screened based on acid and gas production characteristics,acid production rate,and growth curve in glucose fermentation.The selected strains were identified through morphological observation,physiological and biochemical tests,and 16 SrDNA sequence analysis.We further studied the growth temperature range,acid and alkali resistance,salt resistance,acidity,and organic acids components of selected strains.【Result】Four lactic acid bacteria strains,R7,R3,Rg,and Re,were screened.Through morphological observation,physiological and biochemical tests and 16 SrDNA sequence analysis,R7 was Lactobacillus plantarum,R3 was Lactobacillus pentosus,Rg was Lactobacillus fermentum,and Re was Lactobacillus rhamnosus.All the strains can grow at temperatures between 15 to 50 ℃.Strain R7 grew fastest and had the strongest acid produce capacity.Its lactic acid content was also the highest,accounting for 95.40% of the total acid con-tent.It grew well with pH of 3.0and can tolerate NaCl with mass concentration of 0.08g/mL.The growth and acid productions of Re and R3 were less than that of R7,and they also had strong acid and alkali resistance.Rg grew well at temperature of 50 ℃,showing strong high temperature tolerance.【Conclusion】Strains R7,Re,R3 and Rg showed good biological characteristics including fast growth,strong acid production capacity and acid tolerance,and high lactic acid content,and they can be applied to the preparation of pomace silage additives.