Discovering the Molecular Determinants of Phaeobacter inhibens susceptibility to Phaeobacter phage MD18

Bacteriophage technologies have immense potential as antibiotic therapies and in genetic engineering. Understanding the mechanisms that bacteriophages implement to infect their hosts will allow researchers to manipulate these systems and adapt them to specific bacterial targets. Here, we isolated a bacteriophage capable of infecting the marine alphaproteobacterium and dissected its mechanism of infection. phage MD18, a novel species of bacteriophage isolated in Woods Hole, MA, exhibits potent lytic ability against and appears to be of the morphotype. Consistent with this finding, the sequence of the MD18 revealed significant similarity to another siphophage, the recently discovered phage DSS3P8. We incubated MD18 with a library of barcoded transposon insertion mutants and identified 22 genes that appear to be required for phage predation of this host. Network analysis of these genes using genomic position, GO term enrichment, and protein associations reveals that these genes are enriched for roles in assembly of a type IV pilus (T4P) and regulators of cellular morphology. Our results suggest that T4P serve as receptors for a novel marine virus that targets .