Antibacterial activity of hairy-root cultures of Maytenus senegalensis

Hairy-root cultures were established by infecting sterile root segments of Maytenus senegalensis with Agrobacterium rhizogenes strains LBA9402 and A4T. Transformed roots produced more dry biomass (strain LBA9402, 0.22 g; strain A4T, 0.18 g) compared to untransformed roots (0.11 g) over a 3-month culture period. This increased 15- to 20-fold over the controls, after a culture period of 6 months. Transformation had no deleterious effect on the antibacterial activity of the root extracts. The minimal inhibitory concentration (MIC) values against Staphylococcus aureus of root extracts were 0.65 mg/ml (strain LBA9402), 1.25 mg/ml (strain A4T) and > 1.25 mg/ml (untransformed tissues), respectively. Root extracts of both untransformed and transformed root cultures were active against Gram-positive bacterial strains only. Transformation was confirmed using the polymerase chain reaction (PCR) analysis for rolA and rolC genes. Results of the present study indicate that the induction of hairy roots has the potential to increase the yield of antibacterial compounds of pharmaceutical interest in root cultures of M. senegalensis.