A novel temperate phage from Alicyclobacillus : first evidence in this genus of genomic identity to a sigK -integrated prophage

The genus Alicyclobacillus remains a persistent problem for the fruit juice industry, as its thermoacidophilic nature leads to spoilage events that cause product recalls, loss of consumer confidence, and significant economic losses. Yet remarkably little is known about the phages infecting these bacteria, with only two described to date. This study reports the first infectious phage with genomic identity to a prophage in the genus, the Alicyclobacillus phage MMB025. This finding broadens the extremely limited record of Alicyclobacillus phages and reveals integration within the sporulation sigma factor sigK, suggesting a novel link between prophage activity and sporulation regulation in Alicyclobacillus. By combining stability assays, host range testing, and genome analysis, MMB025 represents both a valuable model for phage-spore-former biology and a genetic resource for candidate lysins with potential applications in food preservation.