Lei Zhang,Lingli Zhong,Juying Wang,Yuqiang Zhao,Yiwei Zhang,Yitong Zheng,Weiliang Dong,Xianfeng Ye,Yan Huang,Zhoukun Li,Zhongli Cui
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 α-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 °C) and pH values (5.0–9.0) and recycling. The V max values of AmyM towards wheat and corn raw starch were 1111 and 741 μmol/min/mg without depending on Ca 2+ , 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 malto-oligosaccharides (MOSs) was identified. AmyM achieved high hydrolysis degree of 90% for 30% wheat and corn raw starch after 20 h at 45 °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.
Sphingan WL gum (WL), a kind of exopolysaccharides , is produced by Sphingomonas sp. WG. In this study, citric acid (CA) crosslinked WL hydrogel films were firstly developed for potential wound dressing application. ATR-FTIR and TG results suggested the occurrence of esterification crosslinking. SEM analysis showed that this aided covalent crosslinking could prevent their porous structures from collapsing when swelling. Due to the deprotonation of carboxyl groups, the water absorption capacity of WL-CA hydrogel films increased with the increase of pH (maximum swelling ratio = 38 g/g). The covalent crosslinked swollen WL-CA hydrogels exhibited certain hydrolytic stability, high porosity (>60%), moderate tissue adhesion, and good rheological property (G′ > G″, G′ up to 2 kPa). WL-CA-CIP hydrogel films loaded with antibiotic ciprofloxacin (CIP) showed sustained drug release properties, long-lasting antibacterial activity , and superior biocompatibility. All the results indicated that WL-based hydrogels were potential candidates for wound dressing applications.
危险品化学品经营许可证（带存储）