Complete elimination of indigenously isolated agrobacterium tumefaciens strains by quinolone and metallo beta-lactam antibiotics

ABSTRACT

The present study aimed to isolate Agrobacterium tumefaciens strains from lycoperiscum esculantum [Tomato] galls and investigate in vitro the potential killing activities of various antibiotics. Seven Agrobacterium tumefaciens strains namely WF2, WF7, WF7d, WF11, WF12, WF14 and WF15 were isolated from galls of different lycoperiscum esculantum from various fields in district D.I.Khan. The isolated strains were assayed for their ability to initiate tumors by using a carrot and potato disc assay. Primarly six antibiotics were screened for susceptibility against Agrobacterium tumefaciens by a disc diffusion assay. The antibiotic with the widest zones of inhibition were used for determination of the minimum inhibitory concentration [MIC] and minimum bactericidal concentrations [MBC].The MIC and MBC of meropenem against almost all strains were the same [0.025mg/ml] except for WF14, [MIC/MBC 0.05mg/ml]. The ciprofloxacin was reported as the second most active antibiotic against A. tumefaciens. Suppression of the growth of all strains occurred at 0.0031mg/ml except for WF7 and WF14 with MIC 0.0062mg/ml. The MBCs of all strains are the same as the corresponding MICs. However, the strain WF15 was two times higher [0.0093mg/ml]. The amoxicillin also represented comparatively lower MIC/MBC [0.2mg/ml] except WF14 [MIC 0.4mg/ml, MBC 0.8mg.ml] without clavulanic acid. It is concluded that both meropenem and ciprofloxacin were highly effective in eliminating the Agrobacterium tumefaciens in a low concentration. These findings prove the effective use of ciprofloxacin and meropenem in agrobacterium mediated transformation in plants