Exploring the remarkable diversity of Escherichia coli Phages in the Danish Wastewater Environment, Including 91 Novel Phage Species

Phages drive bacterial diversity - profoundly influencing diverse microbial communities, from microbiomes to the drivers of global biogeochemical cycling. The vast genomic diversity of phages is gradually being uncovered as >8000 phage genomes have now been sequenced. Aiming to broaden our understanding of Escherichia coli (MG1655, K-12) phages, we screened 188 Danish wastewater samples (0.5 ml) and identified 136 phages of which 104 are unique phage species and 91 represent novel species, including several novel lineages. These phages are estimated to represent roughly a third of the true diversity of Escherichia phages in Danish wastewater. The novel phages are remarkably diverse and represent four different families Myoviridae, Siphoviridae, Podoviridae and Microviridae. They group into 14 distinct clusters and nine singletons without any substantial similarity to other phages in the dataset. Their genomes vary drastically in length from merely 5 342 bp to 170 817 kb, with an impressive span of GC contents ranging from 35.3% to 60.0%. Hence, even for a model host bacterium, in the go-to source for phages, substantial diversity remains to be uncovered. These results expand and underlines the range of Escherichia phage diversity and demonstrate how far we are from fully disclosing phage diversity and ecology.