Improvement of Activity and Thermostability of Agar-Entrapped, Thermophilic, Haloalkaliphilic Amylase AmyD8

An extremophilic amylase from Alkalilimnicola sp. NM-DCM-1 was expressed and purified. The amylase, AmyD8, was extremophilic, with maximal activity at 55 °C, pH 10.5 and 2.4 M NaCl. AmyD8 had a broad substrate utilization spectrum, hydrolyzing branched and linear substrates. AmyD8 was stable and active in nonionic and anionic surfactants. AmyD8 was organic solvent resistant, retaining activity after incubation in benzene, methanol, ethanol and isopropanol. AmyD8 was entrapped in an agar–agar matrix with 89% entrapment yield and no loss in relative activity. Entrapped AmyD8 retained its extremophilic properties. Entrapment enhanced AmyD8’s thermal stability, the half-life of the entrapped enzyme nearly doubled after incubation at 50–65 °C. Entrapped AmyD8 had excellent recyclability, retaining 58% of initial activity after 16 hydrolysis cycles. These extreme properties give AmyD8 great economic feasibility. Graphical Abstract