Characterization of Bacillus thuringiensis bacteriophages: morphogenesis, lytic potentials & inter-simple sequence repeat (ISSR) analysis

Abstract

Background Insecticidal crystal proteins (ICPs) produced by Bacillus thuringiensis exhibit strong toxicity. Soil bacteriophages destroy the ICPs in nature. Also, environmental pH, temperature, and ultraviolet (UV) radiation shorten the ICP's validity and infectivity. To Enhance the validity of B. thuringiensis insecticidal (ICPs) the soil Bt phages & the environmental parameters such as soil pH, temperature, and UV should be subjected to continuous evaluation. Result In this study, five B. thuringiensis bacteriophages were isolated, characterized, and named BtØ3, BtØ5, BtØ7, BtØ9, BtØ11. Electron microscopy investigation showed that the five phages have an icosahedral head and a long contractile tail. In addition, the restriction endonuclease BamHI enzyme cleaves the phage genomic DNA suggesting that all five phages have double-stranded DNA (dsDNA) belonging to the order Caudovirales. The various ISSR restriction patterns suggested that the five phages genetically are not similar, and similarity metrics analysis placed the five phages into two clusters. The reported lytic activity of phages against B. thuringiensis was as follows BtØ7 (100%), BtØ9 (100%), BtØ3(83%), BtØ5(83%), and BtØ11(75%). Moreover, the phages were 17% more effective in lysing B. thuringiensis than the commercial antibiotics. Conclusion B. thuringiensis phages isolated from this study highlighted the importance of regular assessment of soil conditions and the lytic potentials of naturally occurring Bt phages to protect B. thuringiensis sp, from being attacked or destroyed, and to calculate the exact Bt dose concentration of successful application in pest control, this will enhance the environmental health, food security, and crop safety.