弱后酸化保加利亚乳杆菌突变菌株的遗传稳定性研究

对从传统乳制品中筛选得到的德氏乳杆菌保加利亚亚种自发突变株KLDS 1.9201-4的遗传稳定性进行研究。将突变菌株进行连续传代,观察形态学变化,利用HPLC分析葡萄糖和乳酸的代谢情况,RAPD分析基因组DNA的稳定性。结果表明,突变菌株KLDS1.9201-4能够稳定遗传至第8代,在传代过程中菌落和菌体特征没有发生明显变化,KLDS 1.9201-4对初始葡萄糖的代谢率逐渐升高,终产物中乳酸的浓度也逐渐升高。KLDS 1.9201-4的基因组DNA相对稳定,没有发生明显变异。弱后酸化德氏乳杆菌保加利亚亚种的自发突变株KLDS 1.9201-4具有适宜的遗传稳定性,可被用于制作弱后酸化的酸奶发酵剂。

Genetic stability of Lactobacillus delbrueckii subsp.Bulgaricus mutant stain with low post-acidification

The genetic stability of a mutant with reduced membrane-bound H+-ATPase activity from L.delbrueckii subsp.bulgaricus originated from the traditional dairy product was studied to develop a yoghurt starter culture with low post-acidification capacity.The mutant was propagated in MRS broth continuously,the morphological trait of mutant was examined by microscope,the glucose and lactic acid content of supernatant of fermented broth was determined by HPLC,and the genome DNA stability was analyzed by RAPD.The result showed that the low post-acidification capacity of mutant strain was still stable while being propagated in MRS broth continuously after eight generation.During this period,the morphological trait of mutant cell didn’t change,the glucose content fermented by KLDS 1.9201-4 and the content of lactic acid of fermented broth increased gradually.Furthermore,the RAPD results showed that the genome DNA of KLDS 1.9201-4 was stable all the time.Thus the L.delbrueckii subsp.bulgaricus mutant KLDS 1.9201-4 with reduced membrane-bound H+-ATPase activity had adequate genetic stability,which could be applied to develop yoghurt starter culture with lower post-acidification.