Screening of Agricultural Wastes for Substrates in Oxalic Acid Production Using Aspergillus niger

The disposal and attendant problems associated with agro-wastes have remained a challenge to the environment. Three agricultural wastes (cassava whey, banana peels and groundnut shells) were collected from the Choba and Yam zone markets in Rivers State, Nigeria and screened for their potential as substrates in the formulation of fermentation media to produce oxalic acid. The inoculum for the study was isolated from the banana peels and identified using the megablast search for highly similar sequences from the NCBI non-redundant nucleotide database. The microbial load and proximate composition of the substrates were determined, and the fermentation media formulated. The organism used for the study was identified as Aspergillus niger MW188538. The results showed a total bacterial count of 9.5x104 cfu/ml, 1.87 x 105 cfu/ml, and 4.0 x 104 cfu/g for cassava whey, banana peels and groundnut shell respectively. The carbohydrates of the cassava whey, banana peels and groundnut shells were 67.74 %w/v, 53.24%w/v and 38.8% w/v respectively. After 12 days of fermentation, the substrates from cassava whey, banana peels, groundnut shells accumulated 2.5 ppm, 1.8 ppm and 1.3 ppm of oxalic acid respectively. The study hypothetically indicates that agro-wastes could be utilized as media components for production of industrial organics.