An endo-β-1, 4-glucanase (EC. from a Neurospora sp isolated from a mouldy corn cob was produced in a solid substrate fermentation (SSF) system of 30.2% moisture level. The enzyme was optimally produced in 48h at an initial culture pH of 6.0 in a medium consisting of corn cob, 5g; defatted melon meal, 1g; MnS04.H20, 2.5mM and sodium dodecyl sulphate (SDS), 0.16%. The relative rates of hydrolysis of carboxymethyl-cellulose, crystalline cellulose and crude lignocellulosic wastes by the crude enzyme extract showed the preference of the enzyme to carboxymethyl-cellulose. The least hydrolyzed cellulose was sigmacel.

Cellulose is the most abundant renewable natural organic resource found in plants, some micro-organisms, and industrial and agricultural residues. Pure cellulose does not occur in nature but is always associated with varying amounts of a variety of non-cellulosic materials especially hemicellulose and lignin (Lutzen et al., 1983).

Cellulose is a high molecular weight linear polymer containing glucose molecules linked by β-1, 4-glycosidic bonds. It is degraded by a complex of three enzymes called cellulases. These are:

Cellobiohydrolase or exoglucanase or exo-1,4-β-glucan cellobiohydrolase (EC. 3.2. 1.91)
Endo-β-glucanase, also called endoglucanase or endo-1, 4-β-D-glucan 4-glucanohydrolase (EC.
Cellobiase or β-glucosidase (EC.

The endo-β-glucanase is an endo-enzyme that attacks cellulose polymers randomly resulting in rapid reduction in chain length and increase in reducing groups and reduction in viscosity.

The cellobiase (β-glucosidase), however, does not attack cellulose but rather the cello-oligosaccharides and cellobiose which inhibit the activities of cellobiohydrolase and endo-β-glucanase. Thus its presence is essential in the complete hydrolysis of cellulose (Halliwell, 1979). Plant biomass and agricultural wastes are in abundance, especially in the tropical savannah and rainforest zones of Africa. Of fundamental importance is the fact that many chemicals and materials must be produced from plant biomass once petroleum, natural gas and coal are no longer affordable or acceptable for use in view of their role in climate change (van Beihen,2008).

Cellulose degradation in nature ensures the maintenance of the carbon cycle and energy transfer among living systems. Without it, dead vegetations would pile up and suppress the formation of new ones causing the atmospheric carbon dioxide pool not to be consumed by photosynthesis (Demain et al., 2005).

Microbial degradation of cellulose has the potential of providing food and energy. For instance, the glucose resulting from cellulose degradation can be fermentatively converted to ethanol and butanol (biofuels), acetone, isopropanol, and biomass in form of single cell protein. In this way, they serve in the production of value-added goods as well as serving as effective means of disposal of such wastes (Sauer, 2008).

Cellulose is degraded by a large number of organisms including the fungi, actinomycetes, myxobacteria and the true bacteria. Most research on cellulase – producing microorganisms has involved fungi’
Neurospora is a perfect ascomycete that is most thoroughly characterized genetically and produces a complete set of cellulases. It is argued that Neurospora is a most favourable organism for the degradation of hemicellulose. For instance, Deshphande et al.(1986) reported the direct conversion of hemicellulose and cellulose to ethanol by Neurospora and Phadtare et al.(1997) reported of Neurospora’s unique ability to convert biomass to ethanol.

Neurospora is peculiarly non-pathogenic, perhaps because it normally has the luxury of growing in a fire scoured landscape, without competitors. So far, no infection or intoxication by Neurospora has ever been reported in human beings, including immune compromised people, or in any live animal or plant (Zhao et al., 1998).

Neurospora is closely related to several industrially important organisms such as Hypocrea jecorina. It is widely consumed as a foodstuff in parts of southeast Asia as the microbial agent in a cultured pressed peanut or soybean cake called “oncham” (The Scientist, 1996). There are reports on the production of cellulase degrading enzymes by species of Neurospora ( Oguntimien et al., 1991).

These studies were carried out by submerged fermentation, a process which is cost-intensive and requires strict asepsis.

In order to reduce the cost of cellulase production, this study aimed at :
i. Optimizing the cultural conditions for endo-β-glucanase production by a Neurospora sp in a solid substrate fermentation (SSF) system, and

ii. studying the kinetics of the degradation of some cellulosic wastes using the crude endo-β-glucanase.

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Item Type: Postgraduate Material  |  Attribute: 69 pages  |  Chapters: 1-5
Format: MS Word  |  Price: N3,000  |  Delivery: Within 30Mins.


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