Purpose: This study was conducted to determine the antimicrobial activity of red and green cactus pear against Escherichia coli O157:H7 in laboratory culture medium (BHI).
Methods: Extracts from pulp and skin of red and green cactus pear were tested against three strains of E. coli O157:H7 individually. Growth over time assay and agar well diffusion assay were used to determine the inhibitory effect of cactus pear.
Results: Our results showed that in control samples, E. coli O157:H7 continue to grow and reached an average of 8.86 ± 0.69 logs CFU/ml, whereas the addition of 20% extract of the red or green cactus pears skins caused the bacterial population to remain within 3.42 ± 0.15 logs CFU/ml, respectively, after 10 h of incubation at 37°C. The minimum inhibitory volumes (MIV), the lowest concentration with significant inhibitory effect, were 400 and 475 µl/ml (V/V) for the skin of red and the skin of green cactus pears, respectively.
Significance: These results indicated that skins of red and green cactus pears have potential antimicrobial effects against the growth E. coli and could provide a natural means of controlling pathogenic contamination.