Production of thermostable xylanase by thermophilic fungal strains isolated from maize silage

Abstract

The search for microorganisms able to produce thermostable xylanases with high yield and characteristics desired for industrial applications has been strongly encouraged since such enzymes are widely used in large-scale processes. In the present study, thermophilic fungal strains able to grow at high temperatures (≥55°C) were isolated from maize silage. The strains were molecularly identified and used for the production of extracellular xylanase by solid-state fermentation using corn cobs as support-substrate material. Species from the genera Rhizomucor and Aspergillus were identified among the isolated strains and these species demonstrated good ability to produce xylanase under solid-state fermentation conditions. Maximal values of enzymatic activity (824 U/g) and productivity (8.59 U/g.h) were obtained with Rh. pusillus SOC-4A (values per g dry weight of fermented medium). The xylanase produced by this fungus presented thermal stability at 75°C, with maximum activity at 70°C and pH 6.0, revealing, therefore, great potential for application in different areas.

Effects of Piromyces sp. CN6 CGMCC 14449 on fermentation quality, nutrient composition and the in vitro degradation rate of whole crop maize silage

“…Factors that high fibre content, poor palatability, and low digestibility of crop straws limit its utilization in the feedstuff industry. Adding a cellulase-secreting fungus or cellulase during the ensiling process can degrade plant cell walls, improve the nutritional quality and reduce crude fibre content of silages, thereby increasing the rate of forage utilization by ruminant animals (Refat et al 2018; Robledo et al 2016).…”

β-Galactosidase-Producing Isolates in Mucoromycota: Screening, Enzyme Production, and Applications for Functional Oligosaccharide Synthesis

“…The power of β-galactosidases to catalyze enzymatic synthesis reactions was examined through the formation of oligosaccharides on different substrates used as glycosyl donors and/or acceptors in mixture. Considering that L. ramosa and R. pusillus exhibited a high β-galactosidase yield and activity during the SSF and the fact that these fungi are important producers of industrial biocatalysts [ 13 , 44 , 45 , 46 ], their enzymes were selected for these experiments. The β-galactosidases obtained in SSF were partially purified, and the crude enzymes were introduced to lactose, skim milk, lactose–fructose, or o NPG–sucrose containing reaction solutions.…”

Extremophilic Prokaryotic Endoxylanases: Diversity, Applicability, and Molecular Insights

“…Low molecular weight (<30 kDa) hemicellulases diffuse rapidly into the rigid lignocellulosic biomass and thus enhance their oxygen penetration rate during the downstream processing over the high molecular weight (>30 kDa) homologs (Breccia et al, 1998;Sharma et al, 2016;Verma et al, 2019). Several fungal xylanases come along with cellulase activity (Subramaniyan and Prema, 2002;Polizeli et al, 2005) that sometimes is not apt for many industries, while the majority of the bacterial xylanases are devoid of such activity and therefore more xylan-specific over the fungal endoxylanases (Robledo et al, 2016). Fungal endoxylanases are being employed in the industries; it may be due to their high production over the bacterial origin, else bacterial endoxylanases provide better alternates than fungi.…”