Box-Behnken design optimization of xylanase and cellulase production by Aspergillus fumigatus on Stipa tenacissima biomass

ABSTRACT

Optimization of xylanase and cellulase production by a newly isolated Aspergillus fumigatus strain grown on Stipa tenacissima (alfa grass) biomass without pretreatment was carried out using a Box-Behnken design. First, the polysaccharides of dried and ground alfa grass were characterized using chemical methods (strong and diluted acid). The effect of substrate particle size on xylanase and carboxymethylcellulase (CMCase) production by the selected and identified strain was then investigated. Thereafter, experiments were statistically planned with a Box-Behnken design to optimize initial pH, cultivation temperature, moisture content, and incubation period using alfa as sole carbon source. The effect of these parameters on the two enzyme production was evaluated using the response surface method. Analysis of variance was also carried out, and production of the enzymes was expressed using a mathematical equation depending on the influencing factors. The effects of individual, interaction, and square terms on production of both enzymes were represented using the nonlinear regression equations with significant R² and P-values. Xylanase and CMCase production levels were enhanced by 25% and 27%, respectively. Thus, this study demonstrated for the first time the potential of alfa as a raw material to produce enzymes without any pretreatment. A set of parameter combinations was found to be effective for the production of xylanase and CMCase by A. fumigatus in an alfa-based solid-state fermentation.

KEYWORDS:

• Alfa
• Aspergillus fumigatus
• Box-Behnken design
• cellulase and xylanase
• solid-state fermentation

ACKNOWLEDGMENTS

The authors thank Dr. Ali Debbi for his assistance and for helping the authors to carry out a part of this work in the Laboratory of Mycology in the Research Center of Bio-Technology (CRBT), Constantine, Algeria.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.