青藏高原垂穗披碱草青贮饲料中乳酸菌的多样性及低温发酵菌株的筛选  

Screening of low-temperature fermentation lactic acid bacteria from silage of Elymus nutans growing on the Qinghai-Tibetan Plateau

作　　者：保安安 张娟[1] 张红梅[2] 柯文灿[1] 陈明[1] 荆佩欣 郭旭生[1] 

机构地区：[1]兰州大学生命科学学院草地农业生态系统国家重点实验室,甘肃兰州730000 [2]兰州大学草地农业科技学院草地农业生态系统国家重点实验室,甘肃兰州730020

出　　处：《微生物学通报》2016年第8期1785-1794,共10页Microbiology China

基　　金：国家自然科学基金项目(No.31272486);甘肃省科技支撑计划项目(No.1304NKCA124)~~

摘　　要：【目的】探究青藏高原垂穗披碱草青贮饲料中乳酸菌的多样性,筛选在低温条件下(10、15和25°C)生长性能较好的优良菌株。【方法】将垂穗披碱草青贮饲料中分离纯化的乳酸菌进行形态特征观察及16S r RNA基因测序鉴定;用MRS液体培养基在10、15和25°C条件下分离、初筛乳酸菌,选取高吸光度值的菌株作为优势菌株。用绿汁发酵液在10、15和25°C条件下培养测定其p H值,选取低p H值菌株作为优势菌株,并综合MRS培养基筛选结果确定优良菌株。【结果】从不同温度和发酵阶段的垂穗披碱草青贮饲料中共分离得到108个乳酸菌菌株,它们分属于6个属、18个种。其中,清酒乳杆菌LS-24在15°C条件下发酵液p H值显著降低(P<0.05),戊糖片球菌PP-63在发酵初期生长速度较快,植物乳杆菌LP-21在15°C条件下发酵液p H值降至3.9且有最大活菌数。【结论】在青藏高原垂穗披碱草青贮饲料中发现的乳酸菌属基本涵盖了前人在常温青贮饲料中发现的所有属,但种数略少;在108株菌中,清酒乳杆菌LS-24、戊糖片球菌PP-63和植物乳杆菌LP-21在低温条件下均表现出较好的繁殖和发酵特性,可作为青贮饲料低温发酵的备选菌株。[Objective] This study is aimed to investigate lactic acid bacteria diversity in Elymus nutans silage, and selected out lactic acid bacteria which grew well at low temperatures of 10, 15 and 25 ℃. [Methods] Lactic acid bacteria （LAB） strains isolated from Elymus nutans silages were identified by 16S rRNA gene sequences. Meanwhile MRS medium was used to choose high absorbance LAB from each species at different temperatures （10, 15 and 25 ℃）, and green juice fermentation was used to get the low PH value one as the dominant LAB at different temperatures （10, 15 and 25 ℃）. [Results] A total of 108 LAB strains were isolated from a variety of stages of fermentation at different temperatures. Based on 16S rRNA gene sequence analysis and phylogenetic tree, these 108 strains were classified into 6 genera and 18 species. In combination with the screening results of culture medium and fermented green juice, we found that LS-24 showed obvious growth advantage at 15 ℃ （P〈0.05）, and PP-63 grew faster in the early stage of fermentation, while LP-21 made pH value dropped to 3.9 at 15 ℃ and had the maximum number of viable cellseory. [Conclusion] The lactic acid bacteria found in this experiment covered almost all common lactic acid bacteria genera found in silages, but species were fewer as compared to the reported lactic acid bacteria from silages. LP-21, LS-24 and PP-63 show a good growth and fermentation characteristics, therefore, these three strains were selected as preferred candidates of lactic acid bacteria strains for low temperature fermentation of ensiling forage.

关 键 词：乳酸菌 青贮 低温发酵 垂穗披碱草 青藏高原 

分 类 号：S816.53[农业科学—饲料科学]