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Updated: Mar 7, 2026
Bacterial Peptide Display for the Selection of Novel Biotinylating Enzymes
Published on: October 3, 2019
A food-grade expression system for d-psicose 3-epimerase production in Bacillus subtilis using an alanine
Jingqi Chen1,2, Zhaoxia Jin3, Yuanming Gai1
1Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308 People's Republic of China.
Background:
Food-grade expression systems require that the resultant strains should only contain materials from food-safe microorganisms, and no antibiotic resistance marker can be utilized. To develop a food-grade expression system for d-psicose 3-epimerase production, we use an alanine racemase-encoding gene as selection marker in Bacillus subtilis.
Results:
In this study, the d-alanine racemase-encoding gene dal was deleted from the chromosome of B. subtilis 1A751 using Cre/lox system to generate the food-grade host. Subsequently, the plasmid-coded selection marker dal was complemented in the food-grade host, and RDPE was thus successfully expressed in dal deletion strain without addition of d-alanine. The selection appeared highly stringent, and the plasmid was stably maintained during culturing. The highest RDPE activity in medium reached 46 U/ml at 72 h which was comparable to RDPE production in kanamycin-based system. Finally, the capacity of the food-grade B. subtilis 1A751D2R was evaluated in a 7.5 l fermentor with a fed-batch fermentation.
Conclusion:
The alanine racemase-encoding gene can be used as a selection marker, and the food-grade expression system was suitable for heterologous proteins production in B. subtilis.
