Table 1. V. fischeri strains used in the study. All strains were the SM morphotype. The strains were described in previous works [18, 24].

Strain	Source	Niche	Location	Squid host colonization phenotype
SA1G	Sepiola affinis	Squid host	Banyuls sur Mer, France	Wild-type
SR5	Sepiola robusta	Squid host	Banyuls sur Mer, France	Wild-type
SI1D	Sepiola intermedia	Squid host	Banyuls sur Mer, France	Wild-type
ES114	Euprymna scolopes	Squid host	Kaneohe Bay, Hawaii, USA	Wild-type
EM17	Euprymna morsei	Squid host	Tokyo Bay, Japan	Wild-type
EB12	Euprymna berryi	Squid host	Tosa Bay, Japan	Wild-type
ET00-3-20	Euprymna tasmanica	Squid host	Sydney, New South Wales, Australia	Wild-type
ET00-7-1	Euprymna tasmanica	Squid host	Sydney, New South Wales, Australia	Wild-type
ATCC 7744	Dead squid	Saprophyte	Coast of Massachusetts, USA	Acute infection, slower growth, increased venting with slower regrowth, lower stationary phase
CG101	Cleidopus gloriamaris	Fish host	Townsville, Queensland, Australia	Chronic infection (persistence), lower stationary phase
MJ1	Monocentris japonicus	Fish host	Southeastern coast of Tokyo, Japan	Acute infection, lower stationary phase, no regrowth after venting
MDR7	Seawater	Bacterioplankton	Marina del Rey, California, USA	No colonization
WH4	Seawater	Bacterioplankton	Woods Hole, Massachusetts, USA	Acute infection, slower growth, increased venting slower regrowth, lower stationary phase