Faculty of Biology, Department of Genetics, Sofia University 'St. Kliment Ohridski', Bulgaria.
Benef Microbes. 2010 Mar;1(1):43-51. doi: 10.3920/BM2008.1004.
Different Enterococci, isolated from starters for the production of the traditional Bulgarian yellow cheese 'Kashkaval' were screened for bacteriocin production, and one of them, Enterococcus faecalis 3915 demonstrated bacteriocin activity. In this study, we investigated the growth parameters of the producer strain as well as the production kinetics and preliminary characterisation of the produced bacteriocin named enterocin 3915. For the growth modelling, the logistic model was used, while bacteriocin production was monitored. Experiments on inducibility were conducted, and strain was checked for the presence of plasmids. The peptide was crudely purified by ammonium sulphate precipitation followed by preparative PAGE. The approximate molecular mass was determined electrophoretically, and the activity was visualised by electrophoresis and agar overlay technique. It was found that E. faecalis 3915 produces a bacteriocin with constitutive synthesis and chromosomal localisation of its genetic determinants. The peptide revealed to be relatively heat-stable with a molecular mass of about 6.5 kDa. As E. faecalis 3915 originates from cheese starter it can be classified as generally recognised as safe (GRAS). The inhibitory activity of enterocin 3915 comprises commensals or pathogens, so properties generally accepted as probiotic could be attributed to the producer, and potential application in the dairy industry is not to be excluded.
从用于生产传统保加利亚黄奶酪“Kashkaval”的发酵剂中筛选出不同的肠球菌，以检测其细菌素的产生能力，其中一株屎肠球菌 3915 表现出细菌素活性。在本研究中，我们研究了产细菌素菌株的生长参数、生产动力学以及所产生的细菌素（命名为肠菌素 3915）的初步特性。生长模型采用逻辑斯谛模型，同时监测细菌素的产生情况。进行了诱导实验，并检查了菌株中是否存在质粒。采用硫酸铵沉淀和制备 PAGE 对肽进行粗纯化。通过电泳确定了近似的分子质量，通过电泳和琼脂覆盖技术观察到了活性。结果表明，屎肠球菌 3915 产生一种具有组成型合成和遗传决定簇染色体定位的细菌素。该肽具有相对耐热性，其分子质量约为 6.5 kDa。由于屎肠球菌 3915 来源于奶酪发酵剂，因此可以被归类为一般认为安全（GRAS）。肠菌素 3915 的抑制活性包含共生菌或病原体，因此通常被认为是益生菌的特性可以归因于生产者，并且不能排除其在乳制品行业的潜在应用。
