Penghui He1, Zeying Zhang2, Dongbo Cai1, Yaozhong Chen1, Hao Wang1, Xuetuan Wei3, Shunyi Li1, Shouwen Chen4. 1. Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Sciences, Hubei University, Wuhan, 430062, People's Republic of China. 2. College of Food Engineering, Wuchang Institute of Technology, Wuhan, 430065, People's Republic of China. 3. College of Food Science and Technology, Huazhong Agricultural University, Wuhan, 430070, People's Republic of China. 4. Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, College of Life Sciences, Hubei University, Wuhan, 430062, People's Republic of China. mel212@126.com.
Abstract
OBJECTIVES: To improve target protein production by manipulating expression levels of alanine racemase in Bacillus licheniformis. RESULTS: The gene of dal was identified to be responsible for alanine racemase function. Based on the selection marker of dal, a food-grade expression system was constructed in B. licheniformis, and effects of different dal expression levels mediated by promoters on α-amylase production were investigated. The highest α-amylase activity (155 U/ml) was obtained in BL10D/pP43SAT-PtetDal, increased by 27% compared with that of the control strain BL10/pP43SAT in tetracycline-based system (123 U/ml). Moreover, the dal transcriptional level was not correlated positively with that of amyL. CONCLUSIONS: A food-grade system for high-level production of α-amylase was constructed in B. licheniformis, revealing that expression levels of selection marker significantly affected target protein production.
OBJECTIVES: To improve target protein production by manipulating expression levels of alanine racemase in Bacillus licheniformis. RESULTS: The gene of dal was identified to be responsible for alanine racemase function. Based on the selection marker of dal, a food-grade expression system was constructed in B. licheniformis, and effects of different dal expression levels mediated by promoters on α-amylase production were investigated. The highest α-amylase activity (155 U/ml) was obtained in BL10D/pP43SAT-PtetDal, increased by 27% compared with that of the control strain BL10/pP43SAT in tetracycline-based system (123 U/ml). Moreover, the dal transcriptional level was not correlated positively with that of amyL. CONCLUSIONS: A food-grade system for high-level production of α-amylase was constructed in B. licheniformis, revealing that expression levels of selection marker significantly affected target protein production.