Nomura M, Kobayashi M, Narita T, Kimoto-Nira H, Okamoto T
Department of Animal Products Research, National Institute of Livestock and Grassland Science, Ikenodai, Tsukuba, Japan.
J Appl Microbiol. 2006 Aug;101(2):396-405. doi: 10.1111/j.1365-2672.2006.02949.x.
The aim of this study was to obtain new Lactococcus lactis strains from nondairy materials for use as milk fermentation starters. The genetic and phenotypic traits of the obtained strains were characterized and compared with those of L. lactis strains derived from milk. It was confirmed that the plant-derived bacteria could be used as milk fermentation starters.
About 2600 lactic acid bacteria were subjected to screening for L. lactis with species-specific PCR. Specific DNA amplification was observed in 106 isolates. Forty-one strains were selected, including 30 strains of milk-derived and 11 of plant-derived, and their phenotypic traits and genetic profiles were determined. The plant-derived strains showed tolerance for high salt concentration and high pH value, and fermented many more kinds of carbohydrates than the milk-derived strains. There were no remarkable differences in the profiles of enzymes, such as lipases, peptidases and phosphatases. Isolates were investigated by cluster analysis based on randomly amplified polymorphic DNA profiles. There were no significant differences between isolates from milk and those from plant. The L. lactis subsp. cremoris strains were clustered into two distinct groups, one composed of the strains having the typical cremoris phenotype and the other composed of strains having a phenotype similar to subsp. lactis. Fermented milk manufactured using the plant-derived strains were not inferior in flavour to that manufactured using the milk-derived strains.
Plant-derived L. lactis strains are genetically close to milk-derived strains but have various additional capabilities, such as the ability to ferment many additional kinds of carbohydrates and greater stress-tolerance compared with the milk-derived strains.
The lactic acid bacteria obtained from plants in this study may be applicable for use in the dairy product industry.
本研究旨在从非乳制品原料中获取新的乳酸乳球菌菌株，用作牛奶发酵剂。对获得的菌株的遗传和表型特征进行了表征，并与源自牛奶的乳酸乳球菌菌株进行了比较。证实了源自植物的细菌可作为牛奶发酵剂。
使用种特异性PCR对约2600株乳酸菌进行乳酸乳球菌筛选。在106株分离物中观察到特异性DNA扩增。选择了41株菌株，包括30株源自牛奶的菌株和11株源自植物的菌株，并确定了它们的表型特征和遗传图谱。源自植物的菌株表现出对高盐浓度和高pH值的耐受性，并且比源自牛奶的菌株能发酵更多种类的碳水化合物。在脂肪酶、肽酶和磷酸酶等酶的图谱方面没有显著差异。基于随机扩增多态性DNA图谱通过聚类分析对分离物进行了研究。源自牛奶的分离物和源自植物的分离物之间没有显著差异。乳酸乳球菌乳脂亚种菌株聚为两个不同的组，一组由具有典型乳脂亚种表型的菌株组成，另一组由具有类似于乳酸亚种表型的菌株组成。使用源自植物的菌株生产的发酵乳在风味上不逊色于使用源自牛奶的菌株生产的发酵乳。
源自植物的乳酸乳球菌菌株在遗传上与源自牛奶的菌株接近，但具有各种额外的能力，例如能够发酵更多种类的碳水化合物，并且与源自牛奶的菌株相比具有更强的抗逆性。
本研究中从植物中获得的乳酸菌可能适用于乳制品工业。
