Control of Endophytic Contamination in Passion Fruit Tissue Culture using Kanamycin

Objective Endophytic contamination severely hinders the successive proliferation of passion fruit tissue culture seedlings. This study aimed to isolate, purify, and identify the endophytic bacteria and determine the types and concentrations of antibiotics that can inhibit their growth, providing a basis for effectively controlling endophytic contamination in passion fruit tissue propagation.

Methods Endophytic bacteria were isolated and purified on agar plates. Strain S4814 was identified through homology analysis of the 16S rDNA sequence. Antibiotic sensitivity screening was carried out using the paper disc diffusion method (K-B method) to identify antibiotics with strong resistance. Subsequently, the growth status of passion fruit tissue culture seedlings was observed in antibiotic culture media with different concentrations to determine the types and concentrations of antibiotics that achieve the best antibacterial effect.

Results Morphological characteristics and 16S rDNA sequencing analysis indicated that the S4814 strain had the highest homology (98.23%) with Frateuria Defendens (Frd) and belonged to the same branch in the evolutionary tree. The K-B method revealed that kanamycin (Kan), cefotaxime sodium (Cef), and carbenicillin (Carb) exhibited strong resistance. The best growth performance of passion fruit tissue culture seedlings was observed in the culture medium supplemented with 50 mg/L kanamycin, with the highest number of new leaf sprouts after 14 days.

Conclusion Strain S4814 was identified as Frd, and the culture medium containing 50 mg/L Kan exhibited the best antibacterial effect, resulting in optimal growth of passion fruit tissue culture seedlings. These findings provide a basis for effectively controlling endophytic contamination in passion fruit tissue propagation.