Screening of filamentous fungi to produce xylanase and xylooligosaccharides in submerged and solid-state cultivations on rice husk, soybean hull, and spent malt as substrates

Abstract

We investigated the enzymatic complex produced by selected fungi strains isolated from the environment using the agro-industrial residues rice husk, soybean hull, and spent malt as substrates. Microbial growth was carried out in solid-state cultivation (SSC) and in submerged cultivations (SC) and the enzymatic activities of xylanase, cellulase, β-xylosidase, and β-glucosidase were determined. All substrates were effective in inducing enzymatic activities, with one strain of Aspergillus brasiliensis BLf1 showing maximum activities for all enzymes, except for cellulases. Using this fungus, the enzymatic activities of xylanase, cellulase, and β-glucosidase were generally higher in SSC compared to SC, producing maxima activities of 120.5, 25.3 and 47.4 U g of dry substrate, respectively. β-xylosidase activity of 28.1 U g of dry substrate was highest in SC. Experimental design was carried out to optimize xylanase activity by A. brasiliensis BLf1 in SSC using rice husk as substrate, producing maximum xylanase activity 183.5 U g dry substrate, and xylooligosaccharides were produced and characterized. These results suggest A. brasiliensis BLf1 can be used to produce important lytic enzymes to be applied in the preparation of xylooligosaccharides.

From lignocellulosic residues to market: Production and commercial potential of xylooligosaccharides

“…Reddy and Krishnan (2016b) and da Silva Menezes et al ( 2017) used solid-state fermentation for the co-production of xylanase and XOS from several agro-residues, using Bacillus subtilis KCX006 and Aspergillus brasiliensis, respectively. However, low yields of XOS were obtained under the optimal conditions, 24.92 mg/g using wheat bran and groundnut oil-cake (Reddy and Krishnan, 2016b), and 14.48 mg/g using rice rusk (da Silva Menezes et al, 2017). The optimization of xylanase production by fermentation requires specific process conditions, distinct from the ones for the optimization of XOS production (Amorim et al, 2019b), including different optimal fermentation times, which probably explains the low yields of XOS obtained.…”

Screening of Lignocellulolytic Enzyme Activities in Fungal Species and Sequential Solid-State and Submerged Cultivation for the Production of Enzyme Cocktails

“…langernariae JCM 9293 was achieved after 9 days of cultivation and was 8.36 U mg −1 , almost two times lower than in F. verticillioides cultivation. Higher xylanase activity the during sequential solid state and submerged cultivation of selected fungi strains is well known in the literature [15,22,65,67,68]. For this kind of research, qualitive and quantitative data comparison is challenging as different researchers show their enzyme activities in different manner [40][41][42][43][44][45][46][47][48][49][50][51][52][53]60,65,67,68].…”

Lipase production by Aspergillus brasiliensis in solid-state cultivation of malt bagasse in different bioreactors configurations

“…Aspergillus brasiliensis 157f was isolated by our group from soil samples in Brazil and was used for the solid-state cultivations because it demonstrated the ability to produce lipase (Da Silva Menezes et al 2017). This strain was isolated, genetically identified, and physiologically characterized for the production of several enzymes in a previous work, and certified lyophilized stocks are kept in our laboratory (Bioteclab, UFRGS, Porto Alegre, Brazil) (Da Silva Menezes et al 2017). For maintenance, the fungus was grown on Petri dishes containing potato dextrose (34 g.L -1 ) and agar (15 g.L -1 ) medium for 7 days at 37 o C for spore collection.…”