Integrated biocatalytic process for trehalose production and separation from rice hydrolysate using a bioreactor system

Rice starch can be hydrolyzed into maltose for trehalose bioconversion by enzymatic methods. In this study, we have successfully established an efficient production system for our recombinant PTTS in large scale. Three bio-treatments were developed to simplify the separation and purification of trehalose from complex rice saccharified liquid. The trehalose conversion rate of 64.63 ± 4.05% at 30 °C can be reached using rice hydrolysate as the substrate in a 5 l fermentor system. By 1% of raw material koji fermentation, the highest concentration of bioethanol (3.61 ± 0.07%) was obtained at 30 °C for 36 h. After 12 h of reaction time, the gluconic acid (24.47 ± 0.33 mM) was successfully produced by glucose oxidase (40 U/g rice) using residual glucose as a substrate. After the batch/continuous ionic exchange process, the trehalose can be successfully separated, crystallized and identified as 92.6 ± 0.02% purity and 94.2% of the recovery yield, respectively.