Analytical study on Fungal Cellulase Produced by Penicillium Expansum grown on Malus Domestica (Apple Fruits)
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Date
2021
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Abstract
The rise in world industrialization and the cost of importing enzyme by local industries have led to a rise in the
search for novel and native enzyme producing microorganisms. Cellulase is an enzyme that catalyzes the breaking
down of carbon chains in cellulose and hemicellulose, this research therefore aimed at studying fungal cellulase
produced by Penicillium expansum grown on malus domestica (apple fruits). Fresh apple fruit was allowed to
deteriorate under laboratory condition until there was visible mould growth. The mould with desired features of
the organism of interest was subcultured by direct plating on PDA plates to which 10 % streptomycin has been
added to prevent bacterial contaminants. The plates were incubated at 28±2 0C for 7 days until a visible mass of
blue mycelia appear. The isolate was further subcultured onto freshly prepared media until pure culture was
obtained. Characterization and identification of isolate were done using macroscopy and microscopy techniques.
The isolate was re-inoculated into healthy apple fruits and the fruits were incubated at temperature of 28±2 oC for
8 days. Cellulolytic activity was examined every day throughout the incubation period. Crude enzyme was
extracted each day using standard methods. Carboxyl methyl cellulose was used as standard for the crude cellulase
activity assay after extraction from the infected apple fruits using Dinitrosalicylic acid (DNSA). Culture
parameters like pH and temperature were also optimized to determine their effect on cellulolytic activity of the
fungus. Cellulase activity was defined as the amount of glucose produced in μmol/mg/min under the assay
condition. The highest cellulase activity of 86.84±0.52 μmol/mg/min was observed on day 6 of incubation at 28±2
oC and at pH 7. In conclusion, it is evident from this research that P. expansum isolated could be used as potential
novel organism for industrial production of cellulase under optimized fermentation conditions