Abstract:
The rising global population pressure generates challenges to fulfill food requirements for the
coming generations in adequate amounts. This suggests that the human population cannot
continue to be entirely dependent on crops, animal husbandry and fisheries for food. Instead,
efforts should be made to enhance the production of other potential alternative sources of food.
To this end the current study has been undertaken to evaluate the production of single cell
protein (SCP) from Aspergillus oryzae using coffee cherry husk and sawdust, to analyze the
nutritional composition of the Aspergillus oryzae biomass produced and to determine the
residual nucleic acid content of the biomass before and after nucleic acid reduction. Soil
samples, coffee cherry husk and sawdust were collected from Southern Nations Nationalities
Peoples Regional State, Gedio Zone, Dilla. Identification of Aspergillus oryzae was done using
Aspergillus flavus and parasiticus agar (AFPA) to differentiate the isolates from Aspergillus
flavus and Aspergillus parasiticus depending on the fungal colony reverse colors on plates. Two
types of sterilized growth substrates, coffee cherry husk and sawdust, were transferred in to two
sterile petri-dishes and inoculated with Aspergillus oryzae suspension containing 106
-107
spores/ml and incubated for seven days. To collect the biomass, 1gm fermented substrate from
each petr-dish transferred to pre-weighed centrifuge tubes and 5ml of sodium sulphate (150 gm
1
-1
) were added to each tube. The tubes were centrifuged at 12000 rpm for 15 minutes. At the
end of centrifugation, the fungal biomass with lower density than the substrate floated while the
substrate settled to the bottom. The biomass were dried and grinded using a mortar and pestle.
Three types of buffers were used for the extraction of total proteins from Aspergillus oryzae. The
collected data were subjected to Analysis of Variance (ANOVA) with three replications using
Statistical Analysis System (SAS) Version 9.0. The highest amount of protein (57.1mg), was
recorded from Aspergillus oryzae grown on 60% CCH + 40% SD alone. Whereas the least
amount of proteins were obtained from grown substrate 100% SD (24.9mg). 60% CCH + 40%
SD is the appropriate combination that produce high amount single cell protein from Aspergillus
oryzae
