Zain Abidin¹*, Subhadra Thampi², Polat Shakarov¹

¹Department of Biological Sciences, University of Maryland, Baltimore, USA

² Cooper Medical School, Rowan University, USA

*Corresponding address: Department of Biological Sciences, University of Maryland, Baltimore County, MD 21250, USA
Email: zainwildelake@gmail.com

Received: 11 August 2025 / Revised: 12 November 2025 / Accepted: 21 November 2025 / Available Online: 15
December 2025

DOI: https://doi.org/10.63137/jsteam.646531

ABSTRACT

Objective: This study aimed to isolate and characterize a novel bacteriophage, designated Infidel, that infects
Bacillus thuringiensis kurstaki (Btk), to enhance understanding of phage diversity, morphology, and host
phage interactions within the Bacillus cereus group.
Methods: Soil samples collected from the University of Maryland, Baltimore County, were enriched with Btk
cultures for phage isolation. Purified plaques were analyzed for morphology and lytic activity. Transmission
electron microscopy (TEM) was used to determine virion dimensions and structure. Phage DNA was extracted
for restriction digestion using seven enzymes and analyzed by agarose gel electrophoresis. Primer extension
assays were conducted to assess genomic distinctiveness. Host range was tested across multiple Bacillus species
to determine infectivity specificity.
Results: Infidel produced circular, slightly turbid plaques with clear centers averaging 3 mm in diameter. TEM
confirmed its classification as a Myoviridae phage, featuring an icosahedral head (98 × 89 nm) and a contractile
tail (250 × 15 nm). DNA was resistant to digestion by several enzymes, suggesting methylation or structural
modification. Only one primer set (3B) yielded two amplicons, indicating partial homology with conserved
Bacillus phage genes. Infidel infected Btk and select Bacillus strains, demonstrating a narrow host range.
Conclusion: Infidel represents a novel Myoviridae phage with distinct morphological and molecular features,
expanding the current understanding of Bacillus thuringiensis phage diversity. Its restricted host range and
unique DNA modification patterns suggest ecological specialization and potential relevance to the persistence
and performance of Btk in agricultural environments.
Keywords: DNA methylation; Electron microscopy; Soil microbiology; Viral host range; Genetic variation

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How to Cite: Abidin Z et al., Isolation and Characterization of Infidel, a Novel Bacteriophage Infecting Bacillus thuringiensis kurstaki (Btk). J Sci Technol Educ Art Med. 2025;2(2):35-43