The Alpha-amylase MrAMY1 is Better Than MrAMY2 in Rice Starch Degradation, Which Promotes Pigments Production in

Previously, the alpha amylase-encoding gene from was heterologously expressed in CICC41233 to promote starch hydrolysis and increase the production of pigments. The target of this study is to screen the effective alpha-amylases from for starch fast degradation and investigated for pigments production. The 13 types of predicted alpha-amylases in the NRRL1597 genome were divided into four classes based on EC number and into five groups based on the glycoside hydrolase sub-family. The predicted alpha-amylases MrAMY1 (protein ID 440333) and MrAMY2 (protein ID 324551) showed the closest match with AOamyA by phylogenetic analysis. The genes encoding alpha-amylase, and were cloned from CICC41233. However, the gene sequence of from CICC41233 differed from that of NRRL1597 in the length of the intron sequence. Furthermore, the overexpressed strain 440333-6A completely degraded the starch of rice grain in 2 d; in contrast, starch (40.32 mg/mL) remained when rice grain was incubated with the overexpressed strain, 324551-D even after 2 d, while 45.43 mg/mL and 10.48 mg/mL starch remained after 2 d and 6 d, respectively, in wild type CICC41233. Compared to that of CICC41233, the total pigments and ethanol-soluble pigments in 440333-6A increased by 71.69% and 119.33% after 6d, respectively; however, it decreased by 21.40%and 26.58% after 6d, respectively, in 324551-D. This study demonstrated that alpha-amylase MrAMY1 was superior to MrAMY2, as it effectively degraded the starch of rice grain and enhanced pigments production.