酵母浸出物对屎肠球菌活菌数的影响

Influence of Yeast Extract on Viable Count of Enterococcus faecium

屎肠球菌(Enterococcus faecium)发酵饲料中的活菌数是保证其功能特性的关键因素,为了提高屎肠球菌发酵过程中的活菌总数,本研究以屎肠球菌为试验菌株,选用4种不同特性的酵母浸出物来考察其对屎肠球菌活菌数的影响。通过单因素试验,确定以酵母浸出物为唯一氮源培养屎肠球菌的活菌数,根据酵母浸出物检测指标找出影响屎肠球菌活菌的关键因子。试验结果表明,培养基中主要提供生长因子和微量元素的酵母浸出物对屎肠球菌的活性有明显的影响,其中游离核苷酸的含量是影响屎肠球菌发酵活菌数重要因子,通过外源添加一定量的游离核苷酸,厌氧培养12 h,获得的最终活菌数为176×10~8 CFU/m L,与未添加游离核苷酸相比,活菌数提高了将近40%。结果显示,在培养基中添加一定量的游离核苷酸可提高屎肠球菌在发酵液中活菌数量,为工业化生产高活菌数的饲用屎肠球菌提供参考和借鉴。

The viable count of Enterococcus faecium was the key factor to functionality of fermented feed.To get the highest viable count of E.faecium during the fermentation period,the effects of the four different characteristics of yeast extracts on that was discussed.With the method of single factor experiment,the viable count of E.faecium was determined by shake-flask cultures using yeast extract as a sole nitrogen source.Then based on the detecting results of yeast extract,the crucial factors of effect on the viable count could be finding out.Experiments have indicated that yeast extract which provides growth factors and microelement has significant impact on the cellular activity of E.faecium,and the initial concentration of free nucleotides in the media was the important factor that affects the vitality of E.faecium.By adding a certain amount of free nucleotides,and incubating under anaerobic conditions for 12 hours,the maximum number of viable count wasattained 176×10^8 CFU/m L,which was nearly 40 % higher than the maximum number of viable count before the optimization process.The conclusion was that the viable count of E.faecium could be improved by added a certain amount of free nucleotides in the initial media,and it was applied to the industrialized production of probiotic strains used in fermented feed production.