The recombinant raw starch-degrading enzyme (LsA175) which harbors the lsa175 gene from Laceyella sacchari LP175 is optimized for expression in Escherichia coli BL21 (DE3). The recombinant strain provides an alternative avenue for enzyme production in a stirrer fermenter with tolerance to shear force and avoids losing stability by protease existing in the native strain. The maximum enzyme production at 4472±112 U g −1 cell dry weight is obtained using the optimum conditions at 22 °C, 1.0 mM IPTG, and 24 h of induction temperature, Isopropyl 𝜷d-1-thiogalactopyranoside (IPTG) concentration, and induction time, respectively. The enzyme production of 4545 ± 89.8 U g −1 cell dry weight is obtained by batch fermentation in a 2.0 L stirrer fermenter and 5329 ± 86.1 U g −1 cell dry weight by continued glucose feeding with high bacterial cell concentration. The uncooked broken rice powder (200 g L −1 ) is hydrolyzed by crude recombinant LsA175 (300 U mL −1 ) at 50 °C for 12 h without the addition of exogenous glucoamylase (GA), yielding 86 ± 1.79 g L −1 reducing sugar. The bioethanol production resulting from modified simultaneous saccharification and fermentation with Kluyveromyces marxianus DMKU-KS07 at 42 °C gave 71.4±4.35 g L −1 ethanol with 88.24% of theoretical ethanol yield. LsA175 presents engaging performances regarding sugar syrup and bioethanol production, which can diminish the cost of production and energy consumption.

Broken Riceberry rice powder was saccharified by ultrasound-assisted enzymatic hydrolysis for the production of sugar syrup containing phenolic compounds. The results showed that total soluble solid (TSS) content at 17.0 ± 0.5°Brix was obtained when sonicating broken Riceberry rice powder (250 g/l) with a low-temperature amylase at 60% amplitude for 20 minutes and subsequent hydrolysis at 50 o C for 12 hours. Upscaled hydrolysis in a 5.0 l reactor gave the highest TSS content and total phenolic content (TPC) at 16.33 ± 0.29°Brix and 5.63 ± 0.12 mg GAE/g sample, respectively. The obtained Riceberry syrup was used for bacterial cellulose (BC) fermentation using Komagataeibacter xylinus AGR 60, which was incubated at room temperature for 4 days and yielded 4.80 ± 0.30 mm of thickness with 2.51 ± 0.24 g of dry weight equivalent to 3.14 ± 0.30 g/l/day. The physical structure of the obtained BC showed a crowded cellulose network, which showed the potential for water holding capacity of a facial mask sheet product. The five facial mask formulations were tested and showed significant results for the storage ability. This study provided an innovative product from the low-cost agricultural crop through the biotechnological process and showed the potential for further application at the commercial level. How to cite this article:Lomthong T, Siripornvisal S, Khunnamwong P. Ultrasoundassisted enzymatic hydrolysis of broken Riceberry rice for sugar syrup production as a substrate for bacterial cellulose facial mask development.