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

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

作者机构：Key Laboratory of Dairy Science Ministry of Education Northeast Agricultural University College of Food Science Northeast Agricultural University College of Animal Sciences Zhejiang University 

出 版 物：《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 (浙江大学学报（英文版）B辑（生物医学与生物技术）)

年 卷 期：2015年第16卷第4期

页      面：317-326页

核心收录：

学科分类：0710[理学-生物学] 1007[医学-药学(可授医学、理学学位)] 100705[医学-微生物与生化药学] 07[理学] 08[工学] 09[农学] 071007[理学-遗传学] 0901[农学-作物学] 071005[理学-微生物学] 0836[工学-生物工程] 090102[农学-作物遗传育种] 10[医学] 

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

主　　题：Gene expression Proteolytic system Lactobacillus bulgaricus Proteinase 

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.