苜蓿粉发酵用乳酸菌的筛选及特性研究

Study on screening and characteristics of lactic acid bacteria for fermenting alfalfa meals

为筛选调制优质动物苜蓿青贮饲料的优良乳酸菌,本试验以从郑州地区9 个苜蓿样品中分离得到的乳酸菌为试验材料,经抗菌活性、生长特性及产酸特性筛选菌株,根据16S r D N A 序列,结合生理生化特征进行菌种鉴定,并通过发酵苜蓿粉考察菌株的发酵特性.结果表明,从分离的1 9 株乳酸菌中筛选到4 株具有高抗菌活性的菌株,其中菌株Z Z U 4 5 7 和Z Z U 4 6 6 在M R S 液体培养基中生长及产酸性能较好,均能够耐受6.5%的盐浓度环境;菌株Z Z U 4 5 7 耐受1 0 -4 5 ℃,以及p H 为3.5的环境,而菌株Z Z U 4 6 6 能够耐受5 -5 0 ℃,以及p H 为4.0的环境;苜蓿粉发酵结果表明接种Z Z U 4 5 7 或Z Z U 4 6 6 在发酵1 8 h 内均能快速产酸,其中接种Z Z U 4 6 6 的苜蓿粉发酵36 h时p H 值达到4.2;结合理化特征及16S r R N A 序列分析结果, Z Z U 4 6 6 被鉴定为融合魏斯氏菌.优良菌株Z Z U 466在苜蓿青贮饲料调制加工中具有潜在的应用价值.

The purpose of this research was to screen high quality lactic acid bacterias for alfalfa silage.9 alfalfa samples of Zhengzhou area were selected by comparing of their antimicrobial activity or growth features and acid production features.Stains of the ideal samples were identified according to the sequence of 16 S r DNA and the physiological and biochemical characteristics.The fermentation features of alfalfa meal for the excellent strains were also studied.We got 4 lactic acid bacterias that performed a higher activity to inhibit of indicator bacterias.Only ZZU 457 and ZZU 466 of 4 strains showed high rate of growth and acidification in MRS liquids.ZZU 457 could tolerant temperature of 10 ~ 4.5 ℃ and low p H environment(p H 3.5).Strain of ZZU 466 could survive in temperature of 5 ~ 50 ℃ and low p H environment(p H 4.0).Results of the alfalfa meal fermentation indicated that both two strains could produce acid quickly within 18 hours,especially for strains of ZZU 466.It could reduce the p H to the lowest value of 4.2 for the alfalfa meal fermentation liquids at36 hours.According to the physiological and biochemical test,analysis of the 16 S r RNA sequence identified that this strains was W.corfusa.The strain of ZZU 466 had potential value of application as an additive in alfalfa silage.