Fungal Biodiversity Producing Cellulase Involved in Efficient Cellulolysis

Abstract

Cellulases are a class of lignocellulolytic enzymes involved in conversion of cellulose into simple sugars. Synergistic action of three principle cellulases, i.e. endoglucanase, exoglucanase, and β-glucosidase, is required for microbial hydrolysis of insoluble cellulose. Among the various microorganisms, fungi is considered as major cellulose decomposer and carries out 80% of the world’s total cellulose breakdown. The fungal species found in animal rumen like the members of Ascomycota, Basidiomycota, and Deuteromycota, are the major cellulose decomposing fungi. Some of the competent cellulolytic fungi comprise the species of Aspergillus, Penicillium, Chaetomium, Trichoderma, Fusarium, Stachybotrys, Cladosporium, Alternaria, Acremonium, Ceratocystis, Myrothecium, Humicola, etc. The bacterial and anaerobic mycological cellulases remain economically less important as they are present as fitted multi-enzyme complexes, repeatedly available as membrane-bound cellulosomes. Due to the presence of these membrane-bound organelles, cellulase enzymes are difficult to recover from individual active enzyme species. On the other hand, cellulases are produced in bulk by aerobic fungi during its growth and are enzymes known to be very adaptive and extracellular in nature. Among the aerobic fungi, certain species are commercially exploited due to the high cellulolytic nature of the enzymes produced by them, for example, Aspergillus, Trichoderma, Penicillium, and Sclerotium. Thermophilic fungi like Talaromyces emersonii, Chaetomium thermophilum, Sporotrichum thermophile, and Thermoascus aurantiacus are capable of decomposing cellulose. Trichoderma species such as T. harzianum, T. koningii, T. longibrachiatum, and T. viride also produce cellulolytic enzymes.