الفهرس 
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Abstract
Recently, increasing resistance of pathogenic bacteria against available antimicrobial agents is of major concern. It is observed that pathogenic bacteria are more and more difficult to treat with existing drugs and to overcome this problem, an antimicrobial drug with a novel mode of action should be developed. Plants are good source of major substances which may serve as antimicrobial agents with no harmful side effects, and has low cost.
Plant samples (mango and mango leaves) were collected from the farm of The Agriculture Research Center, Cairo, Egypt.
1. Different parts of the plant samples (kernels, leaves and pulp) were extracted by different solvents ( ethanol 70%, acetone, water 37°C and boiling water), followed by antibacterial activity test using well diffusion technique.
2. Nine foodborne microorganisms were subjected for investigation in this study, five of them were gram-negative (S. typhi, S. cerro, Sh. dysenteriae, E. coli and P. mirabilis), and the other four were gram-positive (B. cereus, B. lichiniformis, Staph. aureus and L. monocytogenes).
3. The result of leaves extracts as an antibacterial against the pathogenic strains were the weakest especially with aqueous extracts starting to raise with organic solvents (ethanol and acetone) to be moderate activity.
4. Mango juices failed to inhibit any of the pathogens, but the extracts of unripe pulp gave reasonable results with different extracts.
5. On the other hand, the result of kernel extracts were very strong, except for boiling water extract which showed low activity, other solvents showed a good result against all pathogens especially gram-positive bacteria. It was found that kernel is the best part as antibacterial agent.
6. Ethanol 70% was found to be the best organic solvent with mango kernels, it gave the highest measurable inhibition zones, followed by acetone.
7. Listeria monocytogenes was the most susceptible strain to mango kernel extract, it showed highest inhibition zone diameter reached to (33 mm) followed by S. cerro (25 mm) and B. cereus(26 mm).
8. Based on MBC/MIC ratio, we concluded that the ethanolic 70% extract of Alphonso kernels has microbiocide activity on specific bacteria (S. typhimurium, S.cerro, Staph. aureus and L. monocytogenes) but has microbiostatic on activity on the other species (Sh. dysenteriae, E.coli, P. mirabilis, B. cereus and B. lichiniformis). On the other hand, MBC/MIC ratio of ethanolic 70% extract of Awis kernels showed microbiocidal effect only on two species (S. cerro and Staph. aureus) and microbiostatic effect on the other pathogens while Keitt extract showed microbiocide activity only on S. typhimurium,oppositely, Zebda and unripe pulp extract have only bacteristatic effect on all pathogens.
9. It was taken into consideration that different varieties have different effects, and we found that kernels of Alphonso variety was a very good source as antibacterial agent higher than other varieties. It is potent against all pathogens and gave result nearly the same as the result of the broad spectrum antibiotic ciprofloxacin when compared and there was no significant difference between them.
10. As we regard the antibacterial activity in this study to polyphenols, the test of polyphenol content of three varieties of mango kernel (Alphonso, Kiett and Zebda) showed the highest polyphenol content to Alphonso type followed by Awis and Keitt which was logic to the inhibition zone diameters results.
11. The phytochemical screening of ethanol 70% extract of Alphonso kernel exhibited that high value of tannins (+++) which is a large group of polyphenol and which may be responsible for the antibacterial effect.
12. Based on our results of this study, recommendation can be given to use the ethanol 70% extract of Alphonso kernel as natural antibacterial agent to minimize side effects from using the chemical synthetic antibiotic or chemical preservatives.