Hydrolysis of ionic liquid杢reated substrate with an Iocasia fonsfrigidae strain SP3-1 endoglucanase

Abstract

Abstract: Recently we reported the discovery of a novel endoglucanase of the glycoside hydrolase family 12 (GH12) designated IfCelS12A from the haloalkaliphilic anaerobic bacterium Iocasia fonsfrigidae strain SP3-1 which was isolated from a hypersaline pond in the Samut Sakhon province of Thailand (ca. 2017). IfCelS12A exhibits high substrate specificity on carboxymethyl cellulose and amorphous cellulose but low substrate specificity on b-1 3;1 4-glucan. Unlike some endoglucanases of the GH12 family IfCelS12A does not exhibit hydrolytic activity on crystalline cellulose (i.e. Avicel?). High-Pressure Liquid Chromatography (HPLC) and Thin Layer Chromatography (TLC) analyses of products resulting from IfCelS12-mediated hydrolysis indicate mode of action for this enzyme. Notably IfCelS12A preferentially hydrolyzes cellotetraoses cellopentaoses and cellohexaoses with negligible activity on cellobiose or cellotriose. Kinetic analysis with cellopentaose and barely b-d-glucan as cellulosic substrates were conducted. On cellopentaose IfCelS12A demonstrates a 16-fold increase in activity (KM = 0.27 mM; kcat = 0.36 s?1; kcat /KM = 1.34 mM?1 s?1) compared to the enzymatic hydrolysis of barley b-d-glucan (KM: 0.04 mM kcat: 0.51 s?1 kcat /KM = 0.08 mM?1 s?1). Moreover IfCelS12A enzymatic efficacy is stable in hypersaline sodium chlorids (NaCl) solutions (up to 10% NaCl). Specifically IfCel12A retains notable activity after 24 h at 2M NaCl (10% saline solution). IfCelS12A used as a cocktail component with other cellulolytic enzymes and in conjunction with mobile sequestration platform technology offers additional options for deconstruction of ionic liquid杙retreated cellulosic feedstock. Key points: � IfCelS12A from an anaerobic alkaliphile Iocasia fronsfrigidae shows salt tolerance � IfCelS12A in cocktails with other enzymes efficiently degrades cellulosic biomass � IfCelS12A used with mobile enzyme sequestration platforms enhances hydrolysis. ? 2024 The Author(s).