Fig. 2: Host range analysis of unevolved and evolved phages.

a Phylogenetic tree based on the core genes (3,667 of 19,556 genes) of the P. aeruginosa strain collection (80 strains) encompassing four genomic clusters (Cluster 1, black branch, 71.3%; Cluster 2, blue branch, 25.0%; Cluster 3, violet branch, 1.3%; Cluster 4, green branch, 2.5%). Classification of each strain according to its resistance profile (4MRGN, red lettering; 3MRGN, blue lettering; MRGN, multi-resistance Gram-negative). Strains marked with an asterisk were included in the experimental evolution. Activity determination of the unevolved (dark grey) and evolved (R15, blue; R30, green) phages against the bacterial collection by spot assay overlay (heat map). b Percentual (white lettering) and absolute (black lettering) infectivity of each phage among the bacterial collection. Vertical dotted line represents the percentage of bacterial strains susceptible to at least one phage (62.5%). 37.5% (30 strains) of bacterial strains were not susceptible to any phage (CRS, completely resistant strains). c Representation of the infectivity gains and losses of the evolved phages. An infectivity gain (yellow bar) is defined as the capability of an evolved phage to infect a bacterial strain that was initially not susceptible to the phage’s genomically closest unevolved progenitor phage. A loss of infectivity (red bar) occurred when a bacterial strain is susceptible to the unevolved ancestral phage but resistant to the corresponding evolved phage. d Representation of the cumulated infectivity gains of the evolved phages among the evolution strains (ES) or all strains (AS, excluding the ES and CRS). Among the ES (n = 8), three strains (stacked blue boxes, numbers at the side of the boxes indicate the infectivity gains on the according strain) resulted in 14 infectivity gains (Paer85, 8 gains; PAO1, 4 gains; Paer09, 2 gains). The 53 infectivity gains among AS (n = 42) correspond to gains on 22 strains (stacked grey boxes, numbers at the side of the boxes indicate the infectivity gains on the according strain). For direct comparability of the two strain populations (ES and AS), the cumulated values were divided by the number of strains in each group, resulting in averaged gains per strain (yellow circles).