Stoianova L G, Sreoshi Sharma, Egorov N S
Antibiot Khimioter. 2006;51(11-12):11-7.
To increase the nisin synthesizing activity of the natural strain Lactococcus lactis subsp. lactis 119 isolated from sour milk, UV irradiation in different doses was used followed by isolation of productive clones. The highest mutation effect was observed with the dose of 76,000 erg/mm2, when 11% of the cells increased their productivity by 12.8% at the minimum survival rate. Two-step UV irradiation and adaptive selection on the nisin-contaning medium provided isolation of a strain with the activity 42.6% higher than that of the initial strain (3850 IU/ml). Natural and UV-induced variability of the strain by the nisin synthesis, growth rate, carbohydrate consumption and sensitivity to antibiotics of various groups were studied.
为提高从酸牛奶中分离出的天然乳酸乳球菌乳酸亚种119的乳酸链球菌素合成活性，采用不同剂量的紫外线照射，随后分离出高产克隆。当剂量为76,000尔格/平方毫米时，观察到最高的突变效应，此时11%的细胞在最低存活率下其生产力提高了12.8%。两步紫外线照射和在含乳酸链球菌素的培养基上进行适应性选择，分离出了一株活性比初始菌株（3850 IU/ml）高42.6%的菌株。研究了该菌株在乳酸链球菌素合成、生长速率、碳水化合物消耗以及对各类抗生素敏感性方面的天然变异和紫外线诱导变异。
