有益芽孢杆菌受体菌研究

采用酸性茚三酮法测定了30株有益芽胞杆菌的赖氨酸产量，然后在不同的溶菌酶浓度下，对赖氨酸产量超过0．07g/L的21株菌进行原生质体转化质粒pUB110,测定原生质体形成率、原生质体再生率及转化频率，结果6103，6104，6120，6129四株菌的转化频率较高。最后，采用经典遗传学方法选育AEC抗性突变株，使赖氨酸积累提高。其中,B.licheniformis 6104诱变菌株610401能积累赖氨酸2．91g/L ,比出发菌株提高了17倍左右，转化率也提高了一个数量级。通过质粒的再转化试验及传代稳定性试验，进一步证实B.licheniformis 6104及其 突变菌株610401是较好的受体菌，尤其是用于赖氨酸合成酶基因的表达。

RESEARCH ON THE RECEPTOR STRAIN OF BENEFICIAL BACILLI

Because of beneficial Bacilli's importance in microecological production and industry microbiology, it is important to develop an efficient transformation receptor system to express many exogenous genes.The lysine production of 30 beneficial Bacilli had been tested by acidic ninhydrin reaction. The strains which lysine production over 0. 07g/L had been transfered by protoplast with plasmid pUB110 at different lysozyme concentration. The frequency of protoplast formation, protoplast regeneration and transformation had been detected. The results show that strains of 6104, 6103,6120,6129 had been transfered at a frequency of 10 5 , other strains at 10 6 . Then the mutant strains being resistant to AEC had been selected by classical genetic method to promote their lysine production and transfer frequency. Among the 21 mutants B. licheniformis 610401 produced 2.91g/L lysine, almost 17 times more than that of its parent strain 6104 and it had been transfered at a frequency of 10 4 . Through the test of retransformation with plasmid pUB110 from transferant and passage test, B. licheniformis 6104 and its mutant 610401 were proved to be a good receptor for exogenous genes, especially for lysine synthetase expression. At this time, we established a gene cloning receptor system of beneficial Bacilli.