Plant tissue cultures can be contaminated by extensive diversity of bacteria and the contamination is specific to species. The contamination leads to decrease in growth rate of shoot, root, multiplication factor and even cause plant death. The study was conducted on old contaminated in vitro sugarcane culture obtained from laboratory of plant tissue culture from June 2017 to May 2018 at Mekelle University, College of Veterinary Medicine and Tigray Biotechnology center in 14 days. The objective of the study was to isolate, characterize and identify bacteria from contaminated in vitro Sugarcane culture and to test the sensitivity of the isolates to the most commonly used antibiotics. In the present study, Escherichia, Bacillus and Micrococcus were isolated and identified as the major contaminant bacteria from in vitro sugarcane cultures. In antibacterial susceptibility test, the isolates of Bacillus and Micrococcus were susceptible to Gentamicin, Chloramphenicol, Ciprofloxaciline, Tetracycline, Vancomycine, Streptomycin, Penicillin G and Kanamycin demonstrating the efficacy of these antimicrobial for the treatment of sugarcane in vitro culture contamination, the third isolate Escherichia were resistance to all antibiotic agents. The multi-drug resistant Escherichia isolated in the current study may be a threat because it may spread to other cultures found in the laboratory.

Keywords: Antibiotics, Bacterial identification, Drug Sensitivity, In vitro, Plant tissue culture