Supernatant solution of Ogi or Akamu, as known in Yoruba (“omidun”) was investigated for microorganisms associated with cereal mash “ogi”. The isolates were further tested for antimicrobial activities against two primary diarrheagenic organisms (Salmonella abaetetuba ATCC 35460 and Escherichia coli ATCC 25922). Microorganisms from commercially obtained “omidun” samples and control samples from yellow and white maize varieties were isolated and identified. Types of isolates and their percentage incidences were compared among all the investigated “omidun” samples. Antimicrobial activities of the isolates were further tested using disc diffusion assay. Results showed that the varieties of “omidun” samples tested harbour some microorganisms (bacteria, yeasts and mould), which were occur in varying incidence among the tested samples. Inhibition zones expressed by the isolates in this work were greater than that expressed by the control (commercial antibiotics) with values ranging from 4.00mm-21.00mm in diameter. Synergistic antimicrobial effect was observed when the isolates were combined with zone of inhibition (38.00mm), higher than that expressed when each of these organisms when used independently (32.00mm for Lactobacillus plantarum and 34.00mm for Aspergillus fumigatus). Higher antimicrobial activity (38.00mm) was observed when A. fumigatus and different yeast isolates were combined and highest activity was observed when Lactobacillus plantarum was combined with five different yeast isolates (39.00mm). Hence, these findings clearly demonstrated synergistic activity of “omidun” isolates against diarrheagenic organisms.
Keywords : Diarrheagenic; Disc diffusion; Zone of Inhibition; Synergistic effect.