A Chrysoporthe cubensis enzyme cocktail produced from a low-cost carbon source with high biomass hydrolysis efficiency

Thiago Rodrigues Dutra,Sebastião Tavares De Rezende,Ednilson Mascarenhas Varela,Daniel Luciano Falkoski,Adriane Maria Ferreira Milagres,Lílian Da Silva Fialho,Valéria Monteze Guimarães,José Cola Zanuncio

doi:10.1038/s41598-017-04262-y

Thiago Rodrigues Dutra, Sebastião Tavares De Rezende + Show 6 more

Open Access

https://doi.org/10.1038/s41598-017-04262-y

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Abstract

Low cost and high efficiency cellulolytic cocktails can consolidate lignocellulosic ethanol technologies. Sugarcane bagasse (SCB) is a low cost agro-industrial residue, and its use as a carbon source can reduce the costs of fungi cultivation for enzyme production. Chrysoporthe cubensis grown under solid state fermentation (SSF) with wheat bran has potential to produce efficient enzymatic extracts for SCB saccharification. This fungus was grown under submersed fermentation (SmF) and SSF with in natura SCB, pretreated with acid or alkali and with others carbon sources. In natura SCB induced the highest carboxymethylcellulase (CMCase), xylanase, β-xylosidase, α-galactosidase and mannanase activities by C. cubensis under SSF. In natura and washed SCB, inducers of enzyme production under SSF, did not induce high cellulases and hemicellulases production by C. cubensis in SmF. The C. cubensis enzymatic extract produced under SSF with in natura SCB as a carbon source was more efficient for lignocelulolic biomass hydrolysis than extracts produced under SSF with wheat bran and commercial cellulolytic extract. Chrysoporthe cubensis showed high potential for cellulases and hemicellulases production, especially when grown under SSF with in natura SCB as carbon source.

Highlights

Plant biomass conversion to biofuels is a key strategy to replace fossil fuels by cleaner sources as part of the global energy chain[1]
Chemical composition of alkali pretreated sugarcane bagasse SCB consisted of 53.6%, 28.8% and 8.0% of cellulose, hemicellulose and lignin, respectively
The extracts produced by this fungus with alkali and acid pretreated SCB under submerged fermentation (SmF) showed higher specific activities of CMCase (11.5 and 16.9 U mg−1, respectively) than those produced under solid state fermentation (SSF) (2.2 and 5.7 U mg−1 respectively). These results indicate that the best culture condition (SSF or SmF) for both cellulase and hemicellulase production by C. cubensis varies with the carbon source as reported for Lentinusedodes and Pleurotus species[36]

Summary

Introduction

Plant biomass conversion to biofuels is a key strategy to replace fossil fuels by cleaner sources as part of the global energy chain[1]. Brazil is the largest sugarcane producer in the world, producing over 200 million tons of sugarcane bagasse per year[9] The use of this raw material in biotechnological processes is interesting due of its low cost and high abundance[10]. The ascomycete fungus, a Eucalyptus pathogen, Chrysoporthe cubensis cultured on solid medium with wheat bran produced a more efficient enzymatic extract for sugarcane bagasse saccharification than commercial cellulolytic preparations[2, 13]. Extracts produced by this fungus exhibited specific activities of endoglucanase, β-glucosidase, β-xylosidase and pectinase higher than those of a commercial cellulolytic extract[13]

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