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Production of fungal biomass from cormel process waste‐water of cocoyam ( Xanthosoma sagittifolium (L) Schott) using Aspergillus oryzae obtained from cormel flour
Author(s) -
Duru C Chidi,
Uma Ngwanma U
Publication year - 2003
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.1380
Subject(s) - aspergillus oryzae , urea , single cell protein , strain (injury) , biology , biomass (ecology) , food science , fermentation , chemistry , horticulture , botany , agronomy , biochemistry , anatomy
Aspergillus oryzae obtained from spoilt cormel flour was subjected to mutation treatments using X‐rays, solar radiation and bleach. Exposure of A oryzae spores to X‐radiation of 50 kV at 20 mA s and other treatments induced both mutation and lethality in the organism. Following selection and screening of viable colonies on a medium containing cormel process waste‐water as the only carbon source, two strains, A oryzae No 15 and A oryzae No 8, which significantly ( P ≤ 0.05) produced more biomass at a higher growth rate than the wild parent, were chosen for single‐cell protein production. Nutrient content of the single‐cell protein produced by the mutants was comparable to that of the wild type. Addition of 3.0 g each of (NH 4 ) 2 SO 4 , NH 4 NO 3 , NH 4 Cl, and urea in 1 l of Xanthosoma process waste‐water increased the growth rate of mutants, with the highest increase observed with urea. Medium amended with urea also produced fungal biomass with the highest protein level of 7.97 g l −1 for A oryzae No 8 strain compared with a protein yield of 3.97 g l −1 obtained in the control. Total biomass produced after 54 h was 22.47 g l −1 for A oryzae No 15 strain when urea was added, whereas only 15.20 g l −1 was produced when no nitrogen source was added. The optimal temperature for single‐cell protein production was found to be 35 °C and the optimal pH was 3.50. A speed of 100 rpm gave the largest quantity of fungal biomass for the mutants tested. Copyright © 2003 Society of Chemical Industry