The aim of our project is to create a biosensor for evaluating the concentration of L-theanine.
Theanine is an amino acid primarily found in particular plants, especially in tea plant (Camellia sinensis). Theanine boosts alpha brain waves, promoting relaxation. In addition, theanine is one of the taste ingredients in green tea, which is called “umami” in Japanese, meaning pleasant savory taste. For these reasons, green tea containing the more theanine is considered to have the higher quality .
Currently, the theanine content in green tea is measured by instrumental analysis depending on the expensive equipment.
To reduce the cost and special technique required for the measurement, we aimed at developing a bacteria sensor to evaluate the theanine content in green tea based on identification of the genes in Bacillus subtilis that are induced in the presence of theanine.
 Vuong, Quan V., Michael C. Bowyer, and Paul D. Roach. "L‐Theanine: properties, synthesis and isolation from tea." Journal of the Science of Food and Agriculture 91.11 (2011): 1931-1939.
 Shimizu, Yoichiro, et al. "Sensitive enzymatic method for the quantification of theanine, a principal umami component of commercial tea beverages." Food Science and Technology Research 19.5 (2013): 909-913.