Production of cellulolytic and xylanolytic enzymes during growth of anaerobic fungi from ruminant and nonruminant herbivores on different substrates

Abstract

Three anaerobic fungi, two Neocallimastix strains isolated from a ruminant (sheep) and one Piromyces strain isolated from a nonruminant (black rhinoceros), were tested for their ability to ferment a range of substrates. Bagasse, filter paper cellulose, fructose, and wheat straw were good inducers of celluloytic and xylanolytic enzymes. These enzymes were produced constitutively by all three strains, although enzyme activities were generally lower, especially for both Neocallimastix strains, after growth on glucose and other soluble sugars. The isoenzyme patterns of extracellular enzyme preparations of Neocallimastix strains were influenced by the growth substrate.

In vitro fibrolytic potential of anaerobic rumen fungi from ruminants and non-ruminant herbivores

“…The weakening of plant tissues by fungal enzymes accelerates digestion, making rumination more effective in reducing particle size and increasing protozoal and bacterial digestion in the rumen. Because of the ability of cellulases to rapidly attack crystalline cellulose, there has been considerable interest in the fiber-degrading enzymes of anaerobic fungi (Teunissen et al 1993).…”

Comparison of the Growth Kinetics of Anaerobic Gut Fungi on Wheat Straw in Batch Culture

“…These fungi have been isolated from animals in a range of geographically distinct locations and are typified by their ability to colonise and degrade the recalcitrant cell walls of many wild and cultivated plants, including maize stems, rice and wheat straws, Soya hulls and temperate and tropical grasses [2,[5][6][7][8][9][10]. Anaerobic fungi are known to produce a wide range of extra-cellular, plant cell-wall hydrolysing enzymes including cellulases, hemicellulases and esterases and thus they are very effective degraders of lignocellulosic materials [11][12][13][14]. For example, two isolates (Neocallimastix hurleyensis and an Orpinomyces) were able to degrade up to 60% of the apparent cell-wall biomass of wheat straw when grown in continuous flow cultures containing 80-100 g/L wheat straw dry matter (DM) [15,16].…”

Cellulases and hemicellulases of the anaerobic fungus Piromyces constitute a multiprotein cellulose-binding complex and are encoded by multigene families

“…Anaerobic fungi of the class Chytridiomycetes, including members of the genera Neocallimastix and Piromyces, are extremely active digesters of plant cell wall polysaccharides [ 1,2]. Previous reports have shown that true cellulase activity of Neocallimasti frontalis resides in a high molecular weight multiprotein cellulose-binding complex [3,4], composed of 6 polypeptides ranging from 56 kDa to 126 kDa; the complex was very active against crystalline cellulose but differed from the cellulosome of Clostridium thermocellum in containing only a small fraction of the total fungal endoglucanase activity, and appar-ently no xylanase.…”