Limits...
Production of cellobionate from cellulose using an engineered Neurospora crassa strain with laccase and redox mediator addition.

Hildebrand A, Kasuga T, Fan Z - PLoS ONE (2015)

Bottom Line: 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.This paper describes a working concept of cellobionate production from cellulose using the CDH-ATBS-laccase system in a fermentation system.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological and Agricultural Engineering, University of California, Davis, One Shields Avenue, Davis, CA, 95616, United States of America.

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.

No MeSH data available.


Related in: MedlinePlus

Laccase production by N. crassa with induction by 3 μM cycloheximide induction at 48 hours into the fermentation.Results shown are the means of biological triplicates with the error bars representing the standard deviations.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4388835&req=5

pone.0123006.g005: Laccase production by N. crassa with induction by 3 μM cycloheximide induction at 48 hours into the fermentation.Results shown are the means of biological triplicates with the error bars representing the standard deviations.

Mentions: Cycloheximide, D-phenylalanine, and copper sulfate are possible inducers for the N. crassa laccase according to previous studies [22–24,29]. To induce laccase in the N. crassa F5 strain, 3 uM cycloheximide was added after 48 hours of fermentation. After an additional 142 hours of fermentation, 0.15 U/mL of laccase was obtained, a suitable concentration to test in the cellobiose conversion system as shown in Fig 5.


Production of cellobionate from cellulose using an engineered Neurospora crassa strain with laccase and redox mediator addition.

Hildebrand A, Kasuga T, Fan Z - PLoS ONE (2015)

Laccase production by N. crassa with induction by 3 μM cycloheximide induction at 48 hours into the fermentation.Results shown are the means of biological triplicates with the error bars representing the standard deviations.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4388835&req=5

pone.0123006.g005: Laccase production by N. crassa with induction by 3 μM cycloheximide induction at 48 hours into the fermentation.Results shown are the means of biological triplicates with the error bars representing the standard deviations.
Mentions: Cycloheximide, D-phenylalanine, and copper sulfate are possible inducers for the N. crassa laccase according to previous studies [22–24,29]. To induce laccase in the N. crassa F5 strain, 3 uM cycloheximide was added after 48 hours of fermentation. After an additional 142 hours of fermentation, 0.15 U/mL of laccase was obtained, a suitable concentration to test in the cellobiose conversion system as shown in Fig 5.

Bottom Line: 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.This paper describes a working concept of cellobionate production from cellulose using the CDH-ATBS-laccase system in a fermentation system.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological and Agricultural Engineering, University of California, Davis, One Shields Avenue, Davis, CA, 95616, United States of America.

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.

No MeSH data available.


Related in: MedlinePlus