M.A. Thesis:

Antibacterial effect of Leaf and Callus extracts of Hyoscyamus niger L.

In order to evaluate the antibacterial effect of leaf and callus extracts of Hyoscyamus niger, two factorial experiment based on completely randomized design with three replications were carried out on biotechnology laboratory of Islamic Azad university of Sabzevar. At first, the effect of 2,4-D concentration (0.5, 1 and 1.5 mg/l) and BAP concentration (0, 0.5 and 1 mg/l ) on callus induction of leaf explants were studied. The solid MS medium containing 30 g/l sucrose was used in this experiment. The results showed that 2,4-D concentration had significant effects on callus production characteristics of leaf explants. The highest callus induction percentage, callus diameter and fresh weight were observed at 1 mg/l 2,4-D concentration and increasing 2,4-D concentration to 1.5 mg/l significantly decreased callus production characteristics. There was no significant difference between 0.5 and 1 mg/l 2,4-D concentrations for callus production. Application of BAP on culture medium increased callus diameter and fresh weight, but had no significant effect on callus induction percentage. The maximum callus diameter and fresh weight were obtained at 0.5 mg/l BAP concentration. There was no significant difference between 0.5 and 1 mg/l BAP concentrations for callus diameter and fresh weight. After the determination of the best hormonal combination for callus induction, the antibacterial effects of methanol extracts of callus and leaves were compared. Different concentration of methanol extracts of leaves and callus (0(methanol), 1.25, 2.5, 5 and 10 mg/l) were prepared and their effect on growth inhibition of Staphylococcus aureus and Escherichia coli were investigated. The results showed that antibacterial effect of leaves extract was significantly higher than callus extract. The Escherichia coli was more sensitive to Hyoscyamus niger extracts, particular extract of leaves. The highest antibacterial effect of leaves and callus extracts were observed at 5 mg/ml concentration, that this effect for leaf extract significantly more than the control treatment (methanol). There was no significant difference between 5 mg/l concentration of callus extract and control treatment for bacterial growth inhibition. Other concentrations of leaves and callus extracts did not show any superiority compared to methanol. According to results, application of 5 mg/l methanol extract of Hyoscyamus niger leaves is recommended for favourable control of Staphylococcus aureus and Escherichia coli.

Keywords: Hyoscyamus niger, callus induction, Gram-negative bacteria, Gram-positive bacteria, in vitro