Production and Characterization O Cellulolytic Enzymus Ox Fusarium Solawi, Hypoxplon Sp., Podoscypha Petalodes and Fusarium Oxpsporium 1solated from Decaying Tree Trunks
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Date
2023-03
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Kenyatta University
Abstract
Lignocellulosic biomass such as agro-waste is a geographically abundant source of renewable
energy, showing enormous potential to contribute to escalating energy demands. Improving
the industrial economics of cellulase production remains a significant hurdle, thus enhancing
the yield of cellulase production and the catalytic efficiency of cellulases is the key targets for
research and development. The present work focused on analysis of fungi for cellulase
activity and studied the effect of pre-treatment and nitrogen sources on the fermentation
process of said fungi. Fungi were collected from Kenyatta University environs and Congo red
was used to select for significant biomass degrading fungi colonies. The cultures obtained
were used for identification of the fungi via molecular techniques and were found to be
Fusarium solani, Hypoxylon sp., Podoscypha petalodes and Fusarium oxysporam. SSF was
carried out using three substrates; rice husks, Sugarcane bagasse and maize cobs.
Composition analysis of the substrates was conducted and Sugarcane bagasse had the highest
cellulose and hemicellulose composition of the 3 substrates as well as the least lignin
composition. Composition of pre-treated substrates showed that the most significant
breakdown of cellulose in sugarcane bagasse, maize cobs and rice husks was recorded when
the substrates were pre-treated with 0.5M HCL at 121°C for 15 minutes while the most
significant breakdown of hemicellulose and lignin was observed when the substrates were
pre-treated with 0.5M NaOH 121°C for 15 minutes. Nitrogen composition was also
determined and showed Sugarcane bagasse and maize cobs had comparably high nitrogen
levels while rice husks had the least amount of nitrogen. The substrates were divided to three;
untreated, pre-treated -and supplemented with nitrogen sources. For the untreated, the
substrates were used as they were. For the pre-treated, the substrates were exposed to either
acidic or alkaline pH at varying temperatures. For the nitrogen sources, the substrates were
supplemented with four different nitrogen sources. The obtained crude enzyme extracts were
then used to assay for cellulase enzyme activity. The selected fungi were seen to have varying
levels of cellulase activity under different conditions with Fusarium solani and Hypoxylon sp.
having higher enzyme production than Podoscypha petalodes and Fusarium oxysporum. The
4 fungi had highest enzyme production on different days with sugarcane bagasse had
maximum Fpase, endoglucanase and exoglucanase activities were observed mainly on the 3¢
and 6™ day of incubation while maize cobs and rice husks enzyme activity peaks were from
the 12* to the 18™ days of incubation. B- glucosidase consistently peaked from the 12* to the
18 day for all the fungi. Sugarcane bagasse, maize cobs and rice husks pre-treated with
0.5M NaOH produced the highest amount of Fpase, endoglucanase and exoglucanase at
121°C for 15 minutes at 15 psi. Pre-treatment of the substrates with 0.5M HCI did not elicit
high enzyme production except for p-glucosidase. - glucosidase production where the
substrates were pre-treated with 0.5M HCI favored mild temperatures for prolonged periods
90°C for 2 hours conditions over 121°C for 15 minutes at 15 psi conditions. Nitrogen
supplementation had an effect on cellulase activities of the 4 fungi. Organic nitrogen sources
were seen to elicit higher cellulase activities compared with inorganic sources. Organic
nitrogen sources had the highest cellulase production with Yeast extract being in the lead
followed closely by Urea then peptone. Ammonium nitrate had the lowest cellulase
production across the board. Of the three substrates used, Sugarcane bagasse consistently
elicited the highest amount of cellulase enzymes by the four fungi selected followed by maize
cobs while rice husks performed the poorest.
Description
A Thesis Submitted in Partial Fulfilment of the Requirement for the Award of the Degree of Master of Science (Biotechnology) in the School of Pure and Applied Sciences of Kenyatta University March, 2023