Endogenous Bacterial Contamination During In vitro Culture of Table Banana: Identification and Prevention

Abstract

The best medium for single shoot development to obtain contamination free culture of the table bananas Musa sapientum cv. chini champa and sagar was MS + 4.0 mg/l BAP + 1.0 mg/l Kn. Average time required for shoot development was 15- 21 days. The best medium for shoot multiplication was MS + 4.0 mg/l BAP + 2.0 mg/l IAA + 13 % CW and average time required for production of multiple shoots from single shoot was 40- 45 days. Half strength MS + 2.0 mg/l IBA was best for root induction in the regenerated shoots. Although initially surface sterilization was successful, microbial contamination at the base of the explant was observed within 7- 15 days after inoculation which eventually killed the explants. Endogenous microorganisms, mostly bacteria, were observed under microscope. Altogether seven bacterial strains were isolated from the contaminated culture. Four of them were found to be gram positive and the rest were gram negative. The gram positive strains were Cellulomonas uda, C. flavigena, Corynebacterium paurometabolum and Bacillus megaterium. The gram negative strains were identified as Klebsiella sp., Erwinia cypripedii and Pseudomonas sp. All the strains were found to be susceptible to gentamicin. Cent per cent contamination free cultures were obtained by soaking the explants in 160 mg/l gentamicin for one hr and 40 min.