RESUMO
Aim: This research investigated the antibacterial activities of the predominant microorganisms isolated from fermenting cassava mash during fufu production against selected enteropathogenic bacteria. Methodology: Microbiological analysis was carried out on the mash on daily basis during the three-day fermentation period. The pH, TTA and temperature of the fufu were also evaluated. The antibacterial activities of dominant microorganisms from the mash were assayed against the isolated microorganisms and test isolates using disc and agar diffusion methods. Results: The bacteria isolated from the fermenting mash include Bacillus subtilis, Lactobacillus fermentum, L. plantarum, Pediococcus acidilactici, Micrococcus luteus and Staphylococcus aureus while the fungi were Aspergillus flavus, A. niger, A. fumigatus, Geotrichum candidum, Penicillium expansum and Rhizospus stolonifer. The predominant microorganisms were L. plantarum, L. mesenteroides, A. niger, A. fumigatus and G. candidum. The total bacterial, lactic acid bacterial and fungal counts increased from 2.5X105 cfu/ml, 2.0X105 cfu/ml and 1.5X103 cfu/ml to 7.6X106 cfu/ml, 6.7X106 cfu/ml and 1.0X106 cfu/ml respectively. The temperature of cassava mash increased from 26°C to 30°C. The pH decreased from 6.80 to 4.22 while the total titratable acidity increased from 0.70% to 0.94%. Escherichia coli, P. mirabilis, S. typhimurium and S. aureus were inhibited by L. plantarum and L. mesenteroides while E. agglomerans and K. pneumoniae were resistant to L. plantarum and L. mesenteroides respectively. Aspergillus niger and G. candidum inhibited S. aureus but E. agglomerans, K. pneumoniae, P. mirabilis and S. typhimurium were not affected. Enterobacter agglomerans, E. coli, P. mirabilis and S. aureus were inhibited by A. fumigatus while K. pneumoniae and S. typhimurium were resistant. Conclusion: These results suggested that consumption of fufu and other fermented cassava tubers could enhance less susceptibility to diseases caused by the test bacteria and fufu may be recommended for people suffering from infections caused by these microorganisms.
RESUMO
Aims: Previous studies had revealed that cultivation of Pleurotus ostreatus is often met with a lot of challenges ranging from environmental to biological factors which adversely affect the successful cultivation of the mushroom. Hence, a need to determine factors against mycelia colonization of substrate during mushroom’s cultivation. Methodology and Result: Conventional streak method was employed to establish the percentage inhibition as well as intercolony distance between the test organisms obtained from the infected substrate and mycelia of the mushroom during substrate colonization. The test organisms are: a fungus, Kutilakesopsis macalpineae and a bacterium, Pseudomonas tolaasii. The effect of pH and temperature on the mycelia growth of P. ostreatus was also investigated. There was a gradual increase in the percentage inhibition from 33.3 % at 24 h to 75.0 % at 168 h for K. macalpineae and 37.5 % at 24 h to 70.0 at 168 h for P. tolaasii. The inter-colony distance between the antagonists and the mushroom mycelium gradually decreased. Optical density of the mycelium growth was at its optimum at pH 4.5 and temperature of 25 °C respectively. In vitro study also showed a significant increase in the optical density from 0.855±0.03 at 24 h to 1.316±0.02 at 168 h in the absence of test antagonist as against 0.812±0.06 and 0.79±0.02 at 24 h to 1.103±0.03 and 0.902±0.03 at 168 h when K. macalpineae and P.tolaasii were used as test antagonistic respectively. Conclusion, significance and impact of study: Sterilization of substrate is essential to avoid contamination during mycelia colonization. Also, slightly acidic medium and temperature control is necessary for high yield of fruit bodies.