Use of antibiotics for the control of endogenous bacteria aiming the micropropagation of fig trees

The explants decontamination is one of the basic principles for the success of Tissue Culture. One of the problems diagnosed in vitro propagation using fig shoot tips is the endogenous contamination of the explants by bacteria. This study aimed to verify the efficiency of the addition of some antibiotics to the culture medium to control potential endogenous bacteria in fig apical buds. It was evaluated the following antibiotics added to the culture medium: T1 (without antibiotic), T2 (30 mg L-1 of chloramphenicol), T3 (250 mg L-1 of ampicillin sodium), T4 (500 mg L-1 of nalidicic acid), T5 (150 mg L-1 of cephalothin sodium), T6 (500 mg L-1 of tetracycline) and T7 (400 mg L-1 of norfloxacin). Once collected in the field the segments of branches containing the gems were placed in a container with water and subsequently, the apical buds were immersed in 70% ethyl alcohol and sodium hypochlorite 2.5%. All external disinfection procedure of the explants was conducted in a laminar flow chamber. The explants were inoculated in test tubes containing 15 mL of enriched MS basal medium and with doses of antibiotics according to pre-established treatments. After inoculation, the explants were kept in a growth chamber for four days in the dark and then under photoperiods of 16 hours of cold white light and irradiance of 25 µmol m s-1 at 22 ± 3 º C. The results showed that the explants external disinfection was sufficient to control fungal contamination and the addition of antibiotics to the medium after autoclaving was effective to control of endogenous bacteria. The best result was obtained with the antibiotic ampicillin sodium which provided more than 90% of survivor explants.

Ficus carica L.; apical buds; aseptic; in vitro

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