Diversity of cellulase- and xylanase-producing filamentous fungi from termite mounds

Abstract

Cellulases and xylanases are enzymes of industrial significance, particularly in the pulp, paper, textile, and animal feed industries. Moreover, their utilization in the food industry, among them, bakery, brewery, winery and fruit and vegetable juice production, cannot be underestimated. One of the potential sources of enzymes is the filamentous fungi, and hence bio-prospecting of this specific group of microorganisms with the highest levels of cellulase and xylanase secretions is being continuously undertaken. The specific aim of this study was to isolate and characterize cellulase- and xylanase-producing filamentous fungi from termite mounds. Termite mounds have long been established as very good sources of filamentous fungi with the ability to secrete high levels of lignocellulolytic enzymes, and hence an ideal target for the bio-prospecting of cellulases and xylanases. In this study, various groups of filamentous fungi were isolated through enrichment and repeated sub-culturing. This was followed by screening using the Congo red plate-based assay. Cellulase and xylanase activities during the solid-state fermentation of wheat bran were detected and analyzed through spectrophotometry via the 3,5-dinitrosalicylic acid detection system for reducing sugars. The obtained fungal isolates were then finally characterized through zymography, reaction kinetics and morphological studies. Overall, a total of eight different groups of fungi, capable of decomposing cellulose and hemicellulose, were isolated, and their tentative identities established as Fusarium, Didymostible, Penicillium, Phytophthora, Oedocephalum, Aspergillus, Monosporascus and Acremonium. Taken together, findings of this study conceivably showed that termite mounds are a good source of filamentous fungi that in turn are also a good source of cellulases and xylanases that arguably, can be recommended for use in industrial and commercial settings.   Key words: Filamentous fungi, lignocellulosic substrates, lignocellulolytic enzymes, cellulases, xylanases, termite mounds, termite nests, fungal combs.