Novel cellulase recycling method using a combination of Clostridium thermocellum cellulosomes and Thermoanaerobacter brockii β-glucosidase

This report describes a novel recycling method utilizing a combination of Clostridium thermocellum cellulosomes and Thermoanaerobacter brockii beta-glucosidase (CglT). To recover cellulosomes and CglT through re-binding to additional cellulose, a chimeric CBM3-CglT was created by fusing carbohydrate binding module (CBM3) from the scaffolding protein CipA into the N-terminal region of CglT. When a recycling test using cellulosomes and CBM3-CglT was performed on microcrystalline cellulose, the process was capable of 4 rounds of recycling (1% w/v cellulose/round). Although irreversible absorption of cellulosomes and CBM3-CglT into the residues was observed when ammonia-pretreated rice straw and delignified rice straw was used as substrates, a maximum of 2 and 4 recycling rounds (1% w/v glucan/round) were achieved, respectively, consistent with a 70% saccharification rate. This novel recycling method using cellulosomes and CBM3-CglT has great potential as an effective lignocellulose degradation system. (C) 2012 Elsevier Ltd. All rights reserved.