玉米青贮过程中乳酸菌动态变化

为了揭示青贮玉米在发酵过程中乳酸菌数量及种群的动态变化,以及微生物添加剂对乳酸菌种群变化的影响,采用了培养方法计数发酵过程中乳酸菌数目的变化,利用16S rRNA基因序列比对方法分析青贮玉米中乳酸菌的多样性及种群变化趋势。经过对15d时间内青贮玉米中乳酸菌变化趋势的分析显示:一周后对照组乳酸菌数最高达到2.1×106CFU/g,两处理组中处理组Ⅱ乳酸菌数达到最高5.5×107CFU/g;利用MRS平板分离、培养出典型乳酸菌菌落152株,经16S rRNA基因序列比对分析为乳杆菌属和片球菌属,其中86%的菌株属于乳杆菌属。此研究表明微生物添加剂有利于青贮玉米发酵过程中乳酸菌的快速增殖,乳杆菌属和片球菌属都是青贮玉米发酵的启动菌之一,在发酵前期一直存在,但发酵后期乳杆菌属是玉米青贮过程中乳酸菌的主要菌群。

Dynamic Changes of Lactic Acid Bacteria During a 15-day Ensilage of Corn

To analyze the dynamic changes of LAB (Lactic acid bacteria) during a 15-day ensilage of corn and the effect that came from inoculants. Plate isolation and 16S rRNA gene homology methods were used to take count of LAB numbers and analyze the population changes during ensilage of corn. One hundred and fifty two LAB were identified as species of Lactobacillus and Pediococcus which were isolated from fermented corn, whereas 86% colonies were identified as Lactobacillus by 16S rRNA gene sequence analysis. The maximum numbers of control group in fermented corn achieved 2.1 × 106 CFU/g and the second experimental group in fermented corn achieved 5.5 × 107 CFU/g after a week. It accelerated growth of Lactobacillus when microbial additive was added. The initial bacteria during ensilage of corn were Pediococcus and Lactobacillus, the dominant bacterium was Lactobacillus in the later phase.