The Carbon Source Controls the Secretion and Yield of Polysaccharide-Hydrolyzing Enzymes of Basidiomycetes.

Eka Metreveli,Tamar Khardziani,Vladimir Elisashvili

doi:10.3390/biom11091341

Eka Metreveli, Tamar Khardziani + Show 1 more

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https://doi.org/10.3390/biom11091341

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Journal: Biomolecules	Publication Date: Sep 10, 2021
Citations: 7	License type: CC BY 4.0

Affiliation: Agricultural University of Georgia

Abstract

In the present study, the polysaccharide-hydrolyzing secretomes of Irpex lacteus (Fr.) Fr. (1828) BCC104, Pycnoporus coccineus (Fr.) Bondartsev and Singer (1941) BCC310, and Schizophyllum commune Fr. (1815) BCC632 were analyzed in submerged fermentation conditions to elucidate the effect of chemically and structurally different carbon sources on the expression of cellulases and xylanase. Among polymeric substrates, crystalline cellulose appeared to be the best carbon source providing the highest endoglucanase, total cellulase, and xylanase activities. Mandarin pomace as a growth substrate for S. commune allowed to achieve comparatively high volumetric activities of all target enzymes while wheat straw induced a significant secretion of cellulase and xylanase activities of I. lacteus and P. coccineus. An additive effect on the secretion of cellulases and xylanases by the tested fungi was observed when crystalline cellulose was combined with mandarin pomace. In I. lacteus the cellulase and xylanase production is inducible in the presence of cellulose-rich substrates but is suppressed in the presence of an excess of easily metabolizable carbon source. These enzymes are expressed in a coordinated manner under all conditions studied. It was shown that the substitution of glucose in the inoculum medium with Avicel provides accelerated enzyme production by I. lacteus and higher cellulase and xylanase activities of the fungus. These results add new knowledge to the physiology of basidiomycetes to improve cellulase production.

Highlights

Plant biomass is abundant, renewable, rich in carbohydrates, and the most suitable resource for large-scale production of bioenergy and various organic chemicals [1,2]
And structurally different crystalline cellulose, wheat straw, and mandarin pomace were selected as carbon sources and potential stimulators of cellulase and xylanase activities production by the three fungi
I. lacteus is an excellent producer of polysaccharide-hydrolyzing enzymes, which can be used for saccharification of plant biomass with a high yield of sugars

Summary

Introduction

Renewable, rich in carbohydrates, and the most suitable resource for large-scale production of bioenergy and various organic chemicals [1,2]. It is a cheap but complex material consisting of polymers of cellulose, hemicellulose, and lignin; a wide range of hydrolytic and oxidative enzymes is required for their degradation. Wooddecomposing white-rot basidiomycetes (WRB) are excellent producers of enzymes that deconstruct the cell wall of plants [5] Due to their ecological and biological peculiarities, they are highly adapted to different environments and resources.

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