Antagonistic Activity of Mycoflora Associated with Cassava Whey Obtained from Cassava Mills in Benin City, Nigeria

Abstract

Whey (cassava wastewater) is an industrial residue obtained from the processing of cassava into various fermented products such as garri, fufu and lafun. Cassava whey mycoflora and their antagonistic activity against Escherichia coli were determined in this report. The associated fungi were enumerated and isolated by standard microbiological methods. The pH value of cassava whey samples was determined using an electrode pH meter while titratable acidity was by acid-base titration. Antagonistic effects of the fungal isolates against previously identified diarrheagenic E. coli strain 838 and 848 was determined using the agar well diffusion technique with the culture supernatant of each fungus. The highest fungal counts were recorded in factory B (7.80 x 10⁷ cfu/ml) while factory D had the least count of 12.90 x 10⁷cfu/ml.  The fungal isolates identified include; Saccharomyces cerevisiae, Aspergillus niger, Aspergillus flavus, Rhizopus, Fusarium and Mucor species with Saccharomyces cerevisiae having the highest frequency of occurrence (61.10%) in all the samples. The pH values and titratable acidity of the fufu whey samples ranged from 3.75±0.33 to 4.54±0.08 and 3.90±0.14 to 6.06±0.33% respectively. The zone of inhibition of the fungal isolates against E. coli strain 838 ranged from 18.50 ± 2.12mm (Rhizopus sp.) to 25.00 ± 0.00 mm (Saccharomyces cerevisiae) while the zone of inhibition against E. coli strain 848 ranged from 26.00 ± 1.14 mm (Mucor sp.) to 38.00 ± 1.14 mm (Saccharomyces cerevisiae). Cassava whey can be converted into economic value by propagation of yeast biomass for the production of value added products.