ABSTRACT
The study for the production of protease from Aspergillus flavus using wheat bran as substrate under Solid State Fermentation was conducted in University of Abuja, Department of Microbiology. Aspergillus flavus was
isolated from spoilt bread and was identified on the basis of the
morphological assessment such as macroscopic and microscopy. Among the
characteristics used includes: colonial characteristics such surface
appearance, texture and colour of the colonies. The protease activity
increased with increase in the fermentation periods. The quantities of
the protease enzyme produced by the Aspergillus flavus in the
basal medium were measured using UV-Spectrophotometer and the result is
shown in Table 5. The protease activity was found to be higher at day 7
than day 5 and 3 with 4.51±10.06 proteaase Unit/mL, 8.63±0.12 U/mL and
18.93±1.20 AU/mL respectively. the extracellular protease produced by Aspergillus flavus
isolated from spoilt bread in Gwagwalada were not significantly
different at P= 0.05 level of significance. The study demonstrated that Aspergillus flavus was able to produce extracellular protease enzymes important in the decomposition of protein materials.
CHAPTER ONE
1.0 INTRODUCTION
1.1 Background of the study
Protease constitutes a
large and complex group of enzymes that plays an important nutritional
and regulatory role in nature. Proteases are (physiologically)
necessary for living organisms; they are ubiquitous and found in a wide
diversity of sources. Protease is the most important industrial enzyme
of interest accounting for about 60% of the total enzyme market in the
world and account for approximately 40% of the total worldwide
enzyme sale (Godfrey and West, 1996; Chouyyok et al., 2005). They are generally used in detergents (Barindra et al.,
2006), food industries, leather, meat processing, cheese making, silver
recovery from photographic film, production of digestive and certain
medical treatments of inflammation and virulent wounds (Rao et al., 1998; Paranthaman et al., 2009). They also have medical and pharmaceutical applications.
Microbial proteases are degradative enzymes which catalyze the total hydrolysis of proteins (Raju et al., 1994; Haq et al.,
2006). The molecular weight of proteases ranges from 18 – 90 kDa
(Sidney and Lester, 1972). These enzymes are found in a wide diversity
of sources such as plants, animals and microorganisms but they are
mainly produced by bacteria and fungi. Microbial proteases are
predominantly extracellular and can be secreted in the fermentation
medium.
In the production of
protease, it has been shown to be inducible and was affected by the
nature of the substrate used in fermentation. Therefore, the choice of
an appropriate inducing substrate is of great importance. Different
carbon sources such as wheat bran, rice straw, rice bran, cotton and
bagasse have been studied for the induction and biosynthesis of
protease. However, wheat bran is a superior carbon source for the
production of protease by Aspergillus flavus. So the further studies were carried out by using wheat bran as carbon source.
The use of
agro-industrial residues as the basis for cultivation media is a matter
of great interest, aiming to decrease the costs of enzyme production
and meeting the increase in awareness on energy conservation and
recycling (Singh et al., 2009). Major impediments to the
exploitation of commercial enzymes are their yield, stability,
specificity and the cost of production. New enzymes for use in
commercial applications with desirable biochemical and physiochemical
characteristics and low production cost have been focus of much research
(Kabli, 2007). Solid state fermentation (SSF) was chosen for the
present research because it has been reported to be of more grated
productivity than that of submerged fermentation (Ghildyal et al.,
1985; Hesseltine, 1972). Economically, SSF offers many advantages
including superior volumetric productivity, use of simpler machinery,
use of inexpensive substrates, simpler downstream processing, and
lower energy requirements when compared with submerged fermentation
(Paranthaman et al., 2009).
1.2 Aim of the study
The aim of this study was to produce protease from Aspergillus flavus using wheat bran as a substrate under Solid State Fermentation.
1.3 Objectives of the study
The objectives of the study include:
- To isolate Aspergillus flavus from spoilt bread in Gwagwalada.
- To determine the frequencies of occurrence of the isolated Aspergillus flavus from spoilt bread using simple percentages.
- To determinethe proteolytic potential of the isolated fungi using basal medium.
- To determine the quantity of the protease enzyme produced by the isolated fungi using spectrophotometer.