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Updated: Jun 2, 2026

Site-Specific Lysine Lactylation via Genetic Code Expansion in E. coli and Mammalian Cells
Published on: February 24, 2026
A food-grade system for inducible gene expression in Lactobacillus plantarum using an alanine racemase-encoding
Tien-Thanh Nguyen1, Geir Mathiesen, Lasse Fredriksen
1Department of Food Sciences and Technology, University of Natural Resources and Life Sciences, Vienna, Austria.
Abstract:
Food-grade gene expression systems for lactic acid bacteria are useful for applications in the food industry. We describe a new food-grade host/vector system for Lactobacillus plantarum based on pSIP expression vectors and the use of the homologous alanine racemase gene (alr) as selection marker. A new series of expression vectors were constructed by exchanging the erythromycin resistance gene (erm) in pSIP vectors by the L. plantarum WCFS1 alr gene. The vectors were applied for the overexpression of β-galactosidase genes from L. reuteri L103 and L. plantarum WCFS1 in an alr deletion mutant of L. plantarum WCFS1. The expression levels obtained in this way, i.e. without the use of antibiotics, were comparable to the levels obtained with the conventional system based on selection for erythromycin resistance. The new system is suitable for the production of ingredients and additives for the food industry.
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