Engineered Strptococcus thermophilus for Natural Vanillin Production and Its Application in Food Industry

Increased demand for organic food products has made the application of microorganisms as natural catalysts for the synthesis of natural vanillin from propenylbenzene. Due to the antimicrobial capability and antioxidant activity of vanillin, it can be used as a food preservative and flavoring agent in food industries. The object of this project is to design and construct recombinant Strptococcus thermophilus that can be employed as a catalyst for bioconversion of ferulic acid into natural vanillin.
Structural fcs (feruloyl-CoA synthetase) and ech (enoyl-CoA hydratase/aldolase) genes were cloned and expressed. Recombinant plasmid pNZ8048-T5/ech/fcs was transformed into S. thermophilus for production of vanillin from ferulic acid and confirmed by double digestion, nested PCR and sequencing.Gene expression levels were evaluated by High-Performance Liquid Chromatography (HPLC).
Designed recombinant plasmid makes it possible to use the fcs and ech genes as a source of cloning in the expression vector pNZ8048 under the control of phage T5 promoter in S. thermophilus host system, successfully cloned and expressed. The results indicated that the optimal molar conversion of vanillin (62%) and vanillyl alcohol (18%) was obtained after 12 hours and 16 hours, respectively using recombinant S. thermophilus.
The present study provides the first evidence for the synthesis of recombinant vanillin from ferulic acid by S. thermophilus. Given the economic importance of lactic acid bacteria that are Generally Recognized as Safe (GRAS) status and their practical application in the food industries, the results can be used as a base in the production of food-safety products in recombinant probiotics.