Optimization of Cellulase Production by Nigrospora Oryzae (Berk and Br.) Petch and Its Application in Biomass Saccharification and Ethanol Production
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Date
2026-01-10
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elsevier
Abstract
The increasing demand for sustainable biofuel alternatives has intensified the search for new
microbial sources of cellulolytic enzymes. This study aim to evaluate the cellulolytic potential of
Nigrospora oryzae and to optimize its cellulase enzyme production using low-cost lignocellulosic
substrates, specifically maize cobs and sugarcane bagasse, under solid-state fermentation. Additionally, the study assess the efficiency of crude cellulase enzymes in biomass saccharification and
bioethanol production. Molecular identification confirmed the isolate as N. oryzae through ITS
sequencing and phylogenetic analysis. N. oryzae exhibited significant cellulolytic activity on
carboxymethylcellulose-Congo red agar. Maize cobs and sugarcane bagasse were used as primary
substrates for enzyme production. The cultural parameters were optimized using a one-variableat-a-time (OVAT) approach. The peak filter paperase (FPase) activity reached 11.3 ± 0.94 IU/ml
for maize cobs and 8.9 ± 0.47 IU/ml for bagasse on day 9. Additionally, maximum endoglucanase
activity was recorded at 19.7 ± 1.74 IU/ml and 15.5 ± 0.76 IU/ml on day 12, respectively.
Exoglucanase activity peaked at 3.46 ± 0.25 IU/ml for maize cobs and 2.06 ± 0.11 IU/ml for
bagasse. The optimal pH for enzyme secretion ranged from 5 to 6. Nitrogen supplementation with
ammonium nitrate, urea, and peptone significantly enhanced enzyme yields. Among the carbon
sources tested, fructose, mannitol, and sucrose markedly improved enzyme production compared
to glucose, suggesting a partial relief from carbon catabolite repression. An enzyme loading of 5%
optimized saccharification efficiency. Simultaneous saccharification and fermentation (SSF) using
Saccharomyces cerevisiae achieved maximum ethanol concentrations at substrate levels between
5% and 15%, demonstrating the bio-conversion potential of this system. These findings position
Nigrospora oryzae as a promising non-conventional cellulase producer for lignocellulosic
bioconversion, with significant implications for sustainable ethanol production
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Research Article
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Citation
Olivier, D., Omwenga, G. I., Cheruiyot, D. K., & Ngugi, M. P. (2025). Optimization of cellulase production by Nigrospora oryzae (Berk & Br.) Petch and its application in biomass saccharification and ethanol production. Manuscript under review