Enzyme Breakthrough Boosts Rare Sweetener Yield from Stevia
A research team led by Professor Tsubasa Shoji at the Institute of Natural Medicine, University of Toyama—working in collaboration with RIKEN, Suntory Global Innovation Center Ltd., and Osaka University—has made a significant advance in the biosynthesis of rare steviol glycosides. By engineering a single amino acid substitution in the stevia-derived enzyme UGT91D2, the team achieved approximately a tenfold increase in the accumulation of rebaudioside D and rebaudioside M, two highly valued non-caloric natural sweeteners.
As public health concerns over excessive consumption of high-calorie sugars like sucrose and fructose continue to rise, attention has increasingly shifted toward healthier, plant-based alternatives. Stevia (Stevia rebaudiana), a herb native to South America, naturally produces sweet-tasting steviol glycosides such as rebaudioside D and M. However, their low natural yield has posed a challenge, primarily due to the limited catalytic activity of the UGT91D2 enzyme responsible for their synthesis.
In this study, the researchers enhanced the enzyme’s activity by modifying a key amino acid involved in substrate recognition. When the improved enzyme was expressed in the leaves of Nicotiana benthamiana, it resulted in a dramatic increase—around tenfold—in the accumulation of the target sweeteners. This breakthrough marks a major step forward in the sustainable and efficient production of rare natural sweeteners.
The full findings were published on January 9, 2025, in the Journal of Agricultural and Food Chemistry, a peer-reviewed journal of the American Chemical Society.
Original article information
Title
Enhanced Production of Rebaudioside D and Rebaudioside M through V155T Substitution in the Glycosyltransferase UGT91D2 from Stevia rebaudiana
Authors
Tsubasa Shoji, Yoshikazu Tanaka, Yu Nakashima, Eiichi Mizohata, Maki Komaki, Satoko Sugawara, Junichiro Takaya, Keiko Yonekura-Sakakibara, Hiroyuki Morita, Kazuki Saito, Tadayoshi Hirai
Published in
Journal of Agricultural and Food Chemistry, Vol 73, Issue 3 (2025)