Complete Elimination of Indigenously Isolated Agrobacterium Tumefaciens Strains by Quinolone and Metallo β-Lactam Antibiotics

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 Agrobacteriumtumefaciens strains namely WF2, WF7, WF7d, WF11, WF12, WF14 and WF15 were isolated from galls ofdifferent lycoperiscum esculantum from various fields in district D.I.Khan. The isolated strains were assayed fortheir ability to initiate tumors by using a carrot and potato disc assay. Primarly six antibiotics were screened forsusceptibility against Agrobacterium tumefaciens by a disc diffusion assay. The antibiotic with the widest zonesof inhibition were used for determination of the minimum inhibitory concentration (MIC) and minimumbactericidal 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 mostactive antibiotic against A. tumefaciens. Suppression of the growth of all strains occurred at 0.0031mg/ml exceptfor 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 comparativelylower MIC/MBC (0.2mg/ml) except WF14 (MIC 0.4mg/ml, MBC 0.8mg.ml) without clavulanic acid. It isconcluded that both meropenem and ciprofloxacin were highly effective in eliminating the Agrobacteriumtumefaciens in a low concentration. These findings prove the effective use of ciprofloxacin and meropenem inagrobacterium mediated transformation in plants