Valorization of Yam Peel Waste for Single-Cell Protein Production Using Aspergillus niger

Abstract

Agro-industrial waste is a source of nutrients and compounds that can be used to support microbial growth in fermentation processes for the production of bio-products such as enzymes, antibiotics, or single-cell proteins. The microbial biomass is a source of proteins with several advantages over traditional protein sources. This study aimed to produce single-cell protein (SCP) from Aspergillus niger using yam peels as substrate. Aspergillus niger was isolated from garden soil using Sabouraud dextrose agar (SDA) and characterized accordingly. Yam peels a restaurant in processed and analyzed for proximate composition according to standard protocols. The isolate was subjected to submerged fermentation using commercially prepared yeast extract peptone dextrose (YEPD), and the yam peel substrate for a period of 7days on a rotary shaker. Results show that Aspergillus niger isolates had dark to brown colonies with black conidial heads and a pale yellow colour on the reverse of the SDA plate. Microscopically, the conidiophore extended from its hyphae, carrying black globular conidia.  Proximate composition of the yam peels substrate was found to contain carbohydrates (81.73%), lipids (4.17%), proteins (3.5%), moisture (5.19%), ash (5.4%), and fiber (1.85%). Support for higher fungal biomass was observed on yam peel substrate, which attained 0.4 OD (optical density), while the maximum growth on the commercially prepared media (YEPD) was 0.23 OD. Thus, the Yam peel substrate supported significantly higher A. niger biomass yield (0.4 OD) compared to commercial YEPD medium (0.23 OD). It is recommended that agro-industrial wastes such as yam peels and related wastes be used to enhance production of SCP, thereby reducing pollution caused by improper disposal of agro-industrial wastes.