Efficient hydrolysis of raw starch by a maltohexaose-forming α-amylase from Corallococcus sp. EGB

The process of raw starch conversion has attracted extensive attention in recent years due to its high energy conversion efficiency and saving of operational costs. In this study, extensive hydrolysis of raw starch by alpha-amylase AmyM from Corallococcus sp. EGB was investigated with robust substrate and products tolerance. AmyM showed broad substrate specificity toward raw starches with different types, and kept active and stable over a wide range of temperatures (30-70 degrees C) and pH values (5.0-9.0) and recycling. The Vmax values of AmyM towards wheat and corn raw starch were 1111 and 741 mu mol/min/mg without depending on Ca2+, respectively. SEM analysis showed that AmyM hydrolysis results in the formation of porous and creviced surfaces around the starch granules peripheries. The cost-effective conversion of raw starch for the production of maltooligosaccharides (MOSs) was identified. AmyM achieved high hydrolysis degree of 90% for 30% wheat and corn raw starch after 20 h at 45 degrees C with 5 U per mg of raw starch, resulting in formation of 70% MOSs and 30% dextrin. During this process, maltose (G2), maltotriose (G3) and maltotetraose (G4) were produced synchronously with G9 and G11, indicating the potential application in enzymatic conversion of raw starch under low temperature.

Automated summary

The study found that alpha-amylase AmyM from Corallococcus sp. EGB has robust substrate and products tolerance towards raw starch, showing broad specificity towards different types of raw starches and remaining active and stable across a wide range of temperatures and pH values. It was cost-effective and achieved high hydrolysis efficiency for the production of maltooligosaccharides (MOSs).