Table 1. Examples of inter-strain variability in the production of signal molecules^a in different species.

Species	Signal Molecule	ΔActivity (Fold)b	nc	References
Aeromonas hydrophila	BHL and HHLg	1.6	4	[33]
Aeromonas salmonicida	BHL and HHLg	1.4	7d	[33]
Agrobacterium vitis	long-chain AHLs	15.8	12	[34]
Burkholderia vietnamiensis	HHLg	2.5	5	[35]
Erwinia amylovora	AI-2	2.5	7	[36]
Fusobacterium nucleatum	AI-2	9.4	4	[37]
Photobacterium phosphoreum	OH-OHLg	1.8	3	[38]
Porphyromonas gingivalis	AI-2	2.1	6e	[37]
Prevotella intermedia	AI-2	1.4	7d	[37]
Pseudomonas aeruginosa	OdDHLg	65.5	28f	[39]
Vibrio campbellii	CAI-1	2.3	7	[40]
	AI-2	2.3	7
	OH-BHLg	2.3	7
Vibrio harveyi	CAI-1	2.0	5	[40]
	AI-2	3.1	5
	OH-BHLg	4.1	5
Vibrio salmonicida	AHL	1.7	8	[33]
Vibrio vulnificus	AI-2	5.5	16	[41]

^aZone of induction on agar plate or TLC, or level of induction in liquid assays of a signal molecule reporter strain.

^bRatio between strain-producing maximal and minimal levels, respectively.

^cNumber of signal-producing strains considered in the calculation.

^dTwo additional strains were non-producers.

^eThree additional strains were non-producers.

^fEight additional strains were non-producers.

^gBHL, N-butanoyl-L-homoserine lactone; HHL, N-hexanoyl-L-homoserine lactone; OH-OHL, N-(3-hydroxyoctanoyl)-L-homoserine lactone; OdDHL, N-(3-oxododecanoyl)-L-homoserine lactone; OH-BHL, N-(3-hydroxybutanoyl)-L-homoserine lactone.