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Studies on the diversity of phenotypic characteristics of Lactococcus lactis and the technological significance in milk industry

乳酸乳球菌表型特征多样性研究及其在乳品工业中的技术意义

基本信息

批准号：
05660316
负责人：
MORICHI Toshiki
金额：
$ 1.47万
依托单位：
NIHON UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1995
项目状态：
已结题

项目摘要

The main purpose of this study was to elucidate the diversity of species Lactococcus lactis by means of systematic comparative examinations of the difference of the phenotypic characteristics.1. We isolated lactococcal strains that formed colonies on CVT agar (containing 1 ppm crystal violet) from several commercial mixed cheese starters. Although these strains (CVT strains) grew in pairs or short chains in TYG broth (1 % tryptone, 0.5 % yeast extract, 1 % glucose, pH 7.0), they formed extremely long chains and showed peculiar growth behavior i.e., aggregate formation when they were cultivated in TYGC broth containing 30 mM citrate. The majority of CVT strains utilized citric acid in existence of fermentable sugars and produced a large quantity of acetoin and some CVT strains exhibited a rather strong trypsin-like activity. These CVT strains were found to belong to L.lactis subsp.lactis / diacetylactis but they maintained a few characteristics of L.cremoris.2. Using 26 test strains, it was shown that the characteristics of L.cremoris was full of diversity, whereas those of L.lactis / diacetylactis were comparatively uniform.3. We confirmed the existence of plasmid DNA common to CVT strains.CVT strains lost above peculiar growth characteristics and the fermentability of citric acid when these plasmids were cured.4. We extracted the aggregate with distillled water and 1 % and 3 % NaCl solutions, and analyzed the fraction precipitated with 75 % ethanol. It was suggested that the fraction was constituted by polysaccharide, in which mannose was the main component.

本研究的主要目的是通过对乳酸乳球菌表型特征差异的系统比较研究来阐明乳酸乳球菌的多样性.我们从几种商业混合奶酪发酵剂中分离出在CVT琼脂（含有1 ppm结晶紫）上形成菌落的乳球菌菌株。尽管这些菌株（CVT菌株）在TYG肉汤（1%胰蛋白胨、0.5%酵母提取物、1%葡萄糖、pH 7.0）中成对或短链生长，但它们形成极长的链并显示出特殊的生长行为，即，当它们在含有30 mM柠檬酸盐的TYGC肉汤中培养时，形成聚集体。大多数CVT菌株在可发酵糖的存在下利用柠檬酸并产生大量乙偶姻，部分CVT菌株表现出相当强的胰蛋白酶样活性。这些CVT菌株被发现属于乳酸乳杆菌乳酸/二乙酰乳酸亚种，但它们保持了乳脂乳杆菌的一些特征。对26株供试菌株的特性分析表明，乳脂乳杆菌的特性具有多样性，而乳酸乳杆菌和双乙酰乳杆菌的特性比较一致.证实了CVT菌株中存在着共同的质粒DNA，这些质粒被消除后，CVT菌株失去了上述特有的生长特性和柠檬酸发酵能力.我们用蒸馏水和1%和3%NaCl溶液提取聚集体，并分析用75%乙醇沉淀的级分。结果表明，该组分由多糖组成，其中甘露糖是主要成分。