Efficient enzymatic synthesis of <scp>d</scp>‐allulose using a novel <scp>d</scp>‐allulose‐3‐epimerase from <i>Caballeronia insecticola</i>

Abstract

Abstract BACKGROUND Rare sugars have become promising ‘sugar alternatives’ because of their low calories and unique physiological functions. Among the family of rare sugars, d ‐allulose is one of the sugars attracting interest. Ketose 3‐epimerases (KEase), including d ‐tagatose 3‐epimerase (DTEase) and d ‐allulose 3‐epimerase (DAEase), are mainly used for d ‐allulose production. RESULTS In this study, a putative xylose isomerase from Caballeronia insecticola was characterized and identified as a novel DAEase. Caballeronia insecticola DAEase displayed prominent enzymatic properties, and 150 g L −1 d ‐allulose was produced from 500 g L −1 d ‐fructose in 45 min with a conversion rate of 30% and high productivity of 200 g L −1 h −1 . Furthermore, DAEase was employed in a phosphorylation–dephosphorylation cascade reaction, which significantly increased the conversion rate of d ‐allulose. Under optimized conditions, the conversion rate of d ‐allulose was approximately 100% when the concentration of d ‐fructose was 50 mmol L −1 . CONCLUSION This research described a very beneficial and facile approach for d ‐allulose production based on C. insecticola DAEase . © 2022 Society of Chemical Industry.