The Antibacterial Activity of Selected Edible Plant Extracts against Bacillus Cereus

Six presumptive Bacillus cereus isolates were isolated from 49 samples of food, soil, manure and eggshells in Amman, Jordan. One isolate from eggshells was identified, characterized and confirmed to be B. cereus and designated as B. cereus (Ju). Among the 11 water and ethanol plant extracts, which demonstrated the highest antibacterial action against B. cereus (Ju), were sumac fruits (Rhus coriara. L) and rossle flowers (Hipiscus sabdariffa. L). It was found that the inhibition of the growth of bacteria was proportional to the increase of extract concentrations. Using 1, 2 and 4 mg/ml of each of water and ethanol extracts of rossle and sumac resulted in an inhibition activity (mm diameters) of the growth of B. cereus of 2, 6 and 16 and 4, 9 and 12 for rossle and 3, 7 and 15 and 3, 8 and 14 mm, respectively. A complete inhibition of the growth (100%) was demonstrated at the highest concentrations used (1.5mg/ml nutrient agar for sumac and 3.45-4.12 mg/ml media for Rossle). These levels are also found to be as the MIC for the two plant extracts. Heat treatment at 70°C for 3min did not affect the anti B. cereus activities of the two extracts. These two edible plants may have the potential to be used as food preservatives after further investigation on their safety and effectiveness against wider spectra of spoilage microorganisms in food.