Genomic and functional characterization of Bacillus phage BCE1 targeting a key gut bacterium in Aedes albopictus...

Vector-borne diseases remain a major global health challenge, underscoring the need for innovative and ecologically sustainable control strategies. Targeted manipulation of the gut microbiota is emerging as a promising next-generation vector control approach. In our previous study, we demonstrated an innovative bacteriophage-mediated strategy for depletion of an essential gut symbiont (Bacillus cereus) to dissect host-microbe interaction mechanism and to disrupt mosquito larval development in a gnotobiotic Aedes albopictus model. Here we present a detailed characterization of the bacteriophage vB_BceS-BCE1 (BCE1) used in the previous work. Host range, adsorption and replication kinetics, effective multiplicity of infection (MOI), environmental stability, virion morphology, and complete genome architecture were analyzed following contemporary standards. BCE1 exhibited siphovirus morphology and strictly lytic activity against B. cereus, with rapid adsorption rate (∼65% adsorption within 15 min), a short latency period (∼20 min), a moderate burst size (∼60 PFU per infected cell), and strong bacteriolytic activity even at a low initial MOI (0.01). Stability assays showed that BCE1 retained substantial infectivity (∼60%) under highly alkaline conditions (pH 11), consistent with the hyperalkaline ionic milieu of mosquito larval midgut. The 42.1-kb dsDNA genome encoded at least 55 coding sequences and lacked antimicrobial resistance genes, toxin genes, integrase-related genes, and tRNAs, supporting its suitability for field applications. Phylogenetic analyses suggested a close affiliation of BCE1 with the recently described genus Layangavirus, representing a novel species and a novel genus. Together, these findings outline a broader framework for the bacteriophage attributes essential to developing gut microbiota modulation-based vector control strategies in future.