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

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.

Extracellular Enzymatic Activities of Oceanic Pelagic Fungal Strains and the Influence of Temperature

“…Polysaccharides, as the most abundant organic compound class, but also the most complex one, require a wide range of enzymes to degrade them [ 35 , 36 ]. We measured three EEAs responsible for the cleavage of cellulose, xylan, and chitin ( Figure 1 ).…”

Influence of Salinity on the Extracellular Enzymatic Activities of Marine Pelagic Fungi

“…Cellulose is the most common natural polysaccharide [70], so its degradation is crucial in the carbon cycle [71]. Several microorganisms, specially fungi, perform cellulolytic activities with three major classes of enzymes such as endoglucanases, exoglucanases, and β-glucosidases [72][73][74][75][76]. The hydrolysis of cellulose has been reported by a wide variety of marine fungi [67,75,[77][78][79][80][81][82][83][84], but their capability to decompose this complex compound depends on their enzymatic machinery [85].…”

“…As all the studied fungal species displayed enzymatic activities in both media, we suggest that different enzymes might catalyze the same reaction (isoenzymes) and allow them to perform their activities at a wide range of salinities. Nonetheless, it is important to highlight that the degradation of complex compounds also requires a wide range of enzymes [72].…”

Optimised Degradation of Lignocelluloses by Edible Filamentous Fungi for the Efficient Biorefinery of Sugar Beet Pulp

“…In this case, it is possible that the hydrolysis of polysaccharides and the consumption of carbon sources by fungi were more or less efficient. Moreover, the maximum catalytic activity of fungal cellulolytic enzymes, in many cases, is observed at pH 5 [42].…”