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Isolation and characterization of non-cellulolytic Aspergillus flavus EGYPTA5 exhibiting selective ligninolytic potential

Hasanin, Mohamed S., Darwesh, Osama M., Matter, Ibrahim A., El-Saied, Houssni
Biocatalysis and agricultural biotechnology 2019 v.17 pp. 160-167
Aspergillus flavus, Fourier transform infrared spectroscopy, agricultural soils, agricultural wastes, biofuels, biopulping, catechol oxidase, cellulose, cellulosic fibers, cellulosic wastes, chemical analysis, endo-1,4-beta-glucanase, feeds, fungi, industrial applications, laccase, lignin, lignocellulases, lignocellulose, lignocellulosic wastes, nitrate reductase, organic fertilizers, peroxidases, polyphenols, pulp and paper industry, value-added products
Environmental applications of selective lignin-degrading fungi and enzymes are of great interest as alternate technologies for paper industry (biopulping), biofuels, organic fertilizers, animal feeds. For this reason, the current study aimed to isolate selective delignifying fungi to convert the abundant lignocellulosic agricultural wastes into value-added products. From five lignocellulolytic fungi isolated from agricultural soil rich with partial decayed wooden trimmings, one isolate was selected due to its selectivity towards lignin degradation. The selected non-cellulolytic fungus isolate was identified according to morphological and molecular techniques as Aspergillus flavus EGYPTA5 with accession number MH425453. This fungal strain has been proven to cause an efficient and selective degradation of lignin in agricultural lignocellulosic wastes without affecting cellulose content. Lignin peroxidases, laccase, polyphenol oxidase, nitrate reductase and cellulase enzymes from investigating strain were assayed in the current research. All the tested enzymes except cellulase were produced with various activity degrees. Lignin peroxidases were the most active enzyme produced under experimental conditions (reached to 2.45 U/ml). Physical and chemical analysis of lignocellulosic agricultural wastes as well as FTIR analysis confirmed that A. flavus EGYPTA5 could be used as an alternative technology for biotreatment of lignin-rich cellulosic wastes to degrade lignin without affecting cellulose fibers. The isolated fungus and/or its specific-lignolytic enzymes could be applied in various environmental and industrial applications.