title: Production of cellobionate from cellulose using an engineered Neurospora crassa strain with laccase and redox mediator addition.
abstract: We report a novel production process for cellobionic acid from cellulose using an engineered fungal strain with the exogenous addition of laccase and a redox mediator. A previously engineered strain of Neurospora crassa (F5∆ace-1∆cre-1∆ndvB) was shown to produce cellobionate directly from cellulose without the addition of exogenous cellulases. Specifically, N. crassa produces cellulases, which hydrolyze cellulose to cellobiose, and cellobiose dehydrogenase (CDH), which oxidizes cellobiose to cellobionate. However, the conversion of cellobiose to cellobionate is limited by the slow re-oxidation of CDH by molecular oxygen. By adding low concentrations of laccase and a redox mediator to the fermentation, CDH can be efficiently oxidized by the redox mediator, with in-situ re-oxidation of the redox mediator by laccase. The conversion of cellulose to cellobionate was optimized by evaluating pH, buffer, and laccase and redox mediator addition time on the yield of cellobionate. Mass and material balances were performed, and the use of the native N. crassa laccase in such a conversion system was evaluated against the exogenous Pleurotus ostreatus laccase. This paper describes a working concept of cellobionate production from cellulose using the CDH-ATBS-laccase system in a fermentation system.
authors: Department of Biological and Agricultural Engineering, University of California, Davis, One Shields Avenue, Davis, CA, 95616, United States of America.
authors: Amanda
authors: A
authors: Hildebrand
authors: Department of Plant Pathology, University of California, Davis, One Shields Avenue, Davis, CA, 95616, United States of America; United States Department of Agriculture-Agricultural Research Service, Davis, CA, 95616, United States of America.
authors: Takao
authors: T
authors: Kasuga
authors: Department of Biological and Agricultural Engineering, University of California, Davis, One Shields Avenue, Davis, CA, 95616, United States of America.
authors: Zhiliang
authors: Z
authors: Fan
mesh_terms: D052160:Benzothiazoles / Q000378:metabolism; D002237:Carbohydrate Dehydrogenases / Q000378:metabolism*; D002482:Cellulose / Q000378:metabolism*; D004187:Disaccharides / Q000378:metabolism*; D005285:Fermentation; D006868:Hydrolysis; D042845:Laccase / Q000378:metabolism*; D009492:Neurospora crassa / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D010084:Oxidation-Reduction; D013451:Sulfonic Acids / Q000378:metabolism
chemical_list: D052160:Benzothiazoles; D004187:Disaccharides; D013451:Sulfonic Acids; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; C006938:cellobionic acid; D002482:Cellulose; D002237:Carbohydrate Dehydrogenases; C019859:cellobiose-quinone oxidoreductase; D042845:Laccase