Effect of culturing conditions on the expression of key enzymes in the proteolytic system of Lactobacillus bulgaricus  

培养条件对保加利亚乳杆菌蛋白水解体系关键酶基因表达的影响（英文）

作　　者：Jun-cai HOU Fei LIU Da-xi REN Wei-wei HAN Yue-ou DU 

机构地区：[1]Key Laboratory of Dairy Science, Ministry of Education, Northeast Agricultural University [2]College of Food Science, Northeast Agricultural University [3]College of Animal Sciences, Zhejiang University

出　　处：《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》2015年第4期317-326,共10页浙江大学学报（英文版）B辑（生物医学与生物技术）

基　　金：supported by the Program for New Century Excellent Talents in Heilongjiang Provincial University(No.1253-NCEF-006),China

摘　　要：The proteolytic system of Lactobacillus bulgaricus breaks down milk proteins into peptides and amino acids, which are essential for the growth of the bacteria. The aim of this study was to determine the expressions of seven key genes in the proteolytic system under different culturing conditions （different phases, initial pH values, temperatures, and nitrogen sources） using real-time polymerase chain reaction （RT-PCR）. The transcriptions of the seven genes were reduced by 30-fold on average in the stationary phase compared with the exponential growth phase The transcriptions of the seven genes were reduced by 62.5-, 15.0-, and 59.0-fold in the strains KLDS 08006, KLDS 08007, and KLDS 08012, respectively, indicating that the expressions of the seven genes were significantly different among strains. In addition, the expressions of the seven genes were repressed in the MRS medium containing casein peptone. The effect of peptone supply on PepX transcription was the weakest compared with the other six genes, and the impact on OppD transcription was the strongest. Moreover, the expressions of the seven genes were significantly different among different strains （P〈0.05）. All these results indicated that the culturing conditions affected the expression of the proteolytic system genes in Lactobacillus bulgaricus at the transcription level.目的:研究不同培养条件(不同生长阶段、初始pH值、培养温度和氮源)对保加利亚乳杆菌蛋白水解体系关键蛋白酶基因表达的影响。创新点:首次证明在脱脂乳中培养保加利亚乳杆菌可以显著增加蛋白酶体系中关键酶基因表达,而在MRS培养基中,关键酶基因表达则显著下调。方法:应用实时荧光定量聚合酶链反应(qRT-PCR)技术,测定不同生长阶段的3株保加利亚乳杆菌(KLDS 08006、KLDS 08007和KLDS 08012)中7种关键酶基因表达的动态变化规律。结论:研究发现保加利亚乳杆菌的初始pH值、氮源和培养阶段影响关键酶基因的表达。稳定生长期的7个蛋白酶基因表达比指数生长期的表达平均下降30倍,其中KLDS 08006、KLDS 08007和KLDS08012菌株的7个蛋白酶基因表达分别下降62.5、15.0和59.0倍。菌株间的7个蛋白酶基因表达显著不同。研究发现含有酪蛋白胨的MRS培养基抑制7个蛋白酶基因表达,其中对PepX基因表达影响最弱,而对OppD基因表达影响最强。

关 键 词：Gene expression Proteolytic system Lactobacillus bulgaricus PROTEINASE 

分 类 号：Q93[生物学—微生物学] Q78