Host Range of Bacteriophage Filtrates from Soil Targeting Xanthomonas vasicola pv. musacearum
Ritah Nakayinga
*
Department of Biological Sciences, Faculty of Science, Kyambogo University, Kampala, Uganda.
Phyllip Rukundo
Department of Biological Sciences, Faculty of Science, Kyambogo University, Kampala, Uganda.
Isaac Isabirye
Department of Biological Sciences, Faculty of Science, Kyambogo University, Kampala, Uganda.
*Author to whom correspondence should be addressed.
Abstract
Background: Xanthomonas vasicola pv. musacearum is a gram-negative bacterium that causes Banana Xanthomonas Wilt (BXW), a disease that severely affects banana crops. This results in reduced banana production, affects food security and the livelihoods of smallholder farmers. Despite the use of conventional management practices, the disease remains widespread and continues to affect banana plantations. The study aims to determine the host range of bacteriophage filtrates isolated from soils surrounding BXW-infected plants.
Methods: Xanthomonas vasicola pv. musacearum was isolated from exudates of infected BXW-banana plant pseudostems and cultured on agar containing yeast extract, peptone, glucose, cephalexin and cycloheximide (YPGA-CC). The bacterial strains were confirmed using polymerase chain reaction.
Soil samples were collected from three banana gardens affected byBXW. The soil-derived bacteriophage filtrates were enriched using double strength YPG broth while the host range was determined using the spot assay technique.
Results: Bacterial isolates obtained from the exudates of the infected banana plants formed yellowish mucoid colonies on YGPA-CC plates. Xanthomonas vasicola pv. musacearum strains were confirmed by PCR, which yielded a band of approximately 398 base pairs on agarose gel. The host range was between 81% and 86% when tested on 21 Xanthomonas vasicola pv. musacearum strains. No plaque formation was detected on non-Xanthomonas strains. The clear plaques observed on Xanthomonas vasicola pv. musacearum lawns indicate successful lytic infection of the bacteriophage filtrates against the bacteria.
Conclusions: The bacteriophage filtrates isolated from soil surrounding BXW-infected banana plants exhibited a broad host range against Xanthomonas vasicola pv. musacearum strains. These findings highlight their potential as biocontrol agents for managingBXW. To advance their application, further studies are required to isolate individual phage types from the filtrates and characterize them for potential use as biocontrol agents.
Keywords: Bacteriophages, bacteriophages filtrates, host range, soil, Xanthomonas vasicola pv. musacearum, Banana Xanthomonas Wilt