苜蓿青贮用乳酸菌复合系Al2的组成多样性

苜蓿是高蛋白的饲料作物,青贮是保存青草过冬的主要手段,但苜蓿是难青贮的作物,添加乳酸菌制剂是解决苜蓿青贮难的有效措施。本研究室通过连续的限制性培养筛选到苜蓿青贮用乳酸菌复合系Al2,用变性梯度凝胶电泳(DGGE)、平板分离及建立16S rDNA克隆文库3种手段相结合分析Al2的组成多样性,确认Al2复合菌系由7株菌组成,全部属于Lactobacillus。其中3株菌Al2-1i,Al2-2i,Al2-3i通过平板分离得到,分别属于L.plantarum(99.9%)、L.kimchii(99.4%)、L.farciminis(100%)。在Al2复合菌系的16S rDNA克隆文库中,上述7种菌的组成比例分别为55.21%、19.79%、14.58%、3.13%、3.13%、3.13%、1.03%。

Composition diversity of lactic acid bacteria (LAB) community Al2 used for alfalfa silage

Alfalfa is the most important forage grass that is difficult to ensile for good quality.Using silage inoculants are the important way for preservation of alfalfa silage.Through continuous restricted subcultivation,a lactic acid bacteria(LAB) community Al2 was selected from well-fermented alfalfa silage.Plate isolation and Denaturing Gradient Gel Electrophoresis(DGGE),construction of 16S rDNA clone library were used to identify the composition diversity of Al2 community,with 7 strains detected,and they were all belonged to Lactobacillus.The composition ratios of the 7 strains were 55.21%,19.79%,14.58%,3.13%,3.13%,3.13%,1.03% according to 16S rDNA clone library.Al2-1i,Al2-2i,Al2-3i,corresponding to L.plantarum(99.9%),L.kimchii(99.4%),L.farciminis(100%) were detected by plate isolation.Among 3 isolates,Al2-1i had the highest ability of dropping pH and producing lactic acid,and the amount of lactic acid was reach to 18g/L at 24h cultivated in MRS media.The ability of dropping pH and producing lactic acid of Al2-3i was the lowest.From DGGE profiles,the dominant strains in Al2 community were L.plantarum and L.kimchii.L.plantarum was detected during the whole process,and L.kimchii was detected in the later phase.