Smart Yogurt：A possible alternative supply of two liver-protective factors with colonization-prone Lactococcus lactisa
A variety of liver diseases occur throughout the world irrespective of age, sex, region or race. Two important liver-protective factors (glutathione and S-adenosyl methionine) has been applied to prevent and treat many different liver diseases and damage. Due to low stability and short half-life, oral table supply of GSH or SAM might be replaced by a novel strategy of supplying these molecules continuously using our synthetic biology design of smart yogurt. In the experiment, two-functional GSH synthetase gene (gshF) and SAM synthetase gene (metK) were in tandem inserted into the expression vector (pNZ8148), and the resulted plasmid (pNZ-GM) was further employed to construct the target vector pNZ-GMcA by introducing adhesion factor gene (cwaA). This target vector was confirmed by gene sequencing and transformed into food-grade Lactococcus lactis. Further studies showed that the synthetic levels of SAM and GSH were improved greatly with Lactococcus lactis NZ9000/pNZ-GMcA, and the colonization-prone ability was also increased simultaneously. Finally, this recombinant Lactococcus lactis was inoculated to produce our smart yogurt separately or combined with Lactobacillus delbruecki. The present work paved one road to supply liver-protective agents using smart yogurt concept thanks to synthetic biology.