It is well known that various plants (whole or some parts) are of definite
and useful use for human benefit and well fare. One of these benefits is the ability of
many plant seeds, fruits and different parts of exerting antimicrobial activity. The aim
of theses uses is the treatment of various infectious diseases. This would be clearly
understood that such plant may display a role in inactivating the underlying causes of
diseases. These are to include various bacteria and may some of fungi if not extended
to include viruses. Methods: In this study, commercially available black seed oil was
collected from the public market in Libya. The latter was reconstituted with sterile
deionised water to various concentrations and then tested for the antimicrobial activity
using both Gram positive Staphylococcus aureus (ATCC 6538) and Gram negative
Escherichia coli (ATCC C600). Antimicrobial activity evaluations were performed by
the cub-cut agar method and the killing curve (survival curve) method. A further
investigation was to understand the mechanism of action of black seed oil and how it
inactivates bacterial cells was carried out. All antimicrobial investigation studies were
referenced with the efficacy of 5% (v/v) phenol. Results: A distinctive zone of
inhibition was detected at various concentrations of the black seed oil. This was
clearly demonstrated against both S. aureus and E. coli. Survival curve experiments
have demonstrated that S. aureus was more susceptible than E. coli. This was clearly
illustrated in the reduction of log of survivors. This was displayed by 1.7 log kill in
the case of S. aureus whilst 0.9 log of kill for E. coli. Further spectrophotometric
experiments displayed a detection of bacterial organelles over a wave length at A350nm.
This absorbance was followed by the significant reduction in the concentration of
theses organelles. Conclusion: The black seed oil has shown an antimicrobial activity
that able to inactivate both S. aureus and E. coli. Such activity would be elucidated in
its ability to target bacterial cell envelope causing its damage. This might result in
bacterial lysis as a result of losing bacterial components and/or target bacterial
organelles. Black seed oil, therefore, in addition to its role as a part of food
constituents would be of a great benefit for the treatment of various infectious
diseases that are of bacterial origin.

download pdf button 11