Abstract:
Banana (Musa spp.) shoot tip cultures from the INIBAP (International Network for the Improvement of Banana and Plantain) Transit Centre gene bank are routinely screened for bacterial contamination during initiation and subculturing.
The bacteriological test involves streaking of the explant base onto nutrient agar, enriched with 1% glucose and 0.5% yeast extract.
Bacteria have been recovered from 4.5% of the 500 tested accessions.
Over 60% of the contaminants are identified as Bacillus spp.
Culture of 1mm sized meristem tips, isolated from contaminated in vitro cultures, proves to be effective for the elimination of bacteria but risks losing explants (33%) due to establishment failure.
However, up to 100% of the growing meristem tips tested negative for bacteria.
In another experiment a range of antibacterial agents i.e. rifampicin, tetracyclin, streptomycin, trimethoprim, penicillin and bacitracin were tested for their ability to control Bacillus pumilis in banana shoot tips.
Their phytotoxicity was also examined.
Treatment of shoot tips with rifampicin at 100mg.l-1 during 1 month resulted in 100% bacteria-free explants without any phytotoxicity.
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