Table 1.

Examples of phage specificity from natural populations. Habitat refers to the environment from which the samples were selected, and host to the bacterial species used to first visualize the phage. For each study, the number of phages tested is reported and the host range of these phages is described depending on whether the phages were able to infect bacteria from multiple species and/or multiple genera. Finally, we report whether there was variability in phage infectivity on different strains/genotypes within a single bacterial species. In all cases, “n/a” is reported when the phages were not tested in a way that allowed for a given comparison. Two cases show both within-species specificity and an ability to infect multiple species, and these are highlighted in bold to emphasize the difficulty in describing a given phage as “generalist” versus “specialist.” Note that this table is for illustrative purposes and is not exhaustive. For a formal meta-analysis of bacteria-phage infection networks, see recent review by Flores and coauthors [60].

			Host range
Habitat	Host	# Phages tested	Multi-species	Multi-genus	Within-species specificity	Reference
Rhizosphere	Pseudomonas	5	4	0	n/a	Campbell et al. 1995 [61]
Sewage	Multiple hosts	11	n/a	11	n/a	Jensen et al. 1998 [62]
Industrial	Leuconostoc	6	0	0	Yes	Barrangou et al. 2002 [63]
Marine	Vibrio	13	10	n/a	Yes	Comeau et al. 2005 [64]
Soil	Burkholderia	6	6	n/a	Yes	Seed and Dennis 2005 [65]
Effluent	Salmonella	66	n/a	0	Yes	McLaughlin et al. 2006 [66]
Marine	Cellulophaga	46	0	0	Yes	Holmfeldt et al. 2007 [67]