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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

pH effect on the conversion of cellobiose to CBA via CDH-ABTS-laccase mediated conversion.Acidic conditions (pH 4 and pH 6) used 50 mM sodium citrate buffer; pH 7.2 and pH 8 used 50 mM sodium phosphate buffer. The Vogels pH 6 condition used 1x Vogel’s salts medium. The results shown are the means of biological duplicates with the error bars representing the standard deviation.
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pone.0123006.g002: pH effect on the conversion of cellobiose to CBA via CDH-ABTS-laccase mediated conversion.Acidic conditions (pH 4 and pH 6) used 50 mM sodium citrate buffer; pH 7.2 and pH 8 used 50 mM sodium phosphate buffer. The Vogels pH 6 condition used 1x Vogel’s salts medium. The results shown are the means of biological duplicates with the error bars representing the standard deviation.

Mentions: Acidic, neutral, and basic conditions were tested to determine the effect of pH on the conversion of cellobiose to CBA. The time course of the conversion of cellobiose to CBA is shown in Fig 2. For conditions at pH 6, conversion was completed within 24 hours with an average of 27.9 mM cellobiose converted to 28.6 mM CBA, resulting in an approximate 1:1 molar conversion, as expected. The data obtained support the efficacy of CDH-ABTS-laccase system for converting cellobiose to cellobionate. However, it strictly requires an acidic conditions for the efficient conversion of cellobiose to CBA with the specific CDH and laccase used in this study.


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)

pH effect on the conversion of cellobiose to CBA via CDH-ABTS-laccase mediated conversion.Acidic conditions (pH 4 and pH 6) used 50 mM sodium citrate buffer; pH 7.2 and pH 8 used 50 mM sodium phosphate buffer. The Vogels pH 6 condition used 1x Vogel’s salts medium. The results shown are the means of biological duplicates with the error bars representing the standard deviation.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0123006.g002: pH effect on the conversion of cellobiose to CBA via CDH-ABTS-laccase mediated conversion.Acidic conditions (pH 4 and pH 6) used 50 mM sodium citrate buffer; pH 7.2 and pH 8 used 50 mM sodium phosphate buffer. The Vogels pH 6 condition used 1x Vogel’s salts medium. The results shown are the means of biological duplicates with the error bars representing the standard deviation.
Mentions: Acidic, neutral, and basic conditions were tested to determine the effect of pH on the conversion of cellobiose to CBA. The time course of the conversion of cellobiose to CBA is shown in Fig 2. For conditions at pH 6, conversion was completed within 24 hours with an average of 27.9 mM cellobiose converted to 28.6 mM CBA, resulting in an approximate 1:1 molar conversion, as expected. The data obtained support the efficacy of CDH-ABTS-laccase system for converting cellobiose to cellobionate. However, it strictly requires an acidic conditions for the efficient conversion of cellobiose to CBA with the specific CDH and laccase used in this study.

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