Meeting Abstract
The beneficial association between squids in the family Sepiolidae (Mollusca: Cephalopoda) and bioluminescent bacteria in the family Vibrionaceae form a unique relationship that provides a model to study the interactions between animals and bacteria. Sepiolid squids from the Mediterranean Sea (genus Sepiola) are unique in that these squids serve as hosts for two bioluminescent bacterial species: Vibrio logei and Vibrio fischeri. Vibrio bacteria produce unique communication molecules known as acyl-homoserine lactones (AHLs) that used to modulate light via quorum sensing (QS). Since V. logei and V. fischeri differ in many of their physiological properties, we examined whether these species produce AHLs that could be “understood” by the other species, and whether the regulatory genes controlling AHL production and subsequently luminescence are genetically distinct. We created a null mutation on the response regulator gene luxO to determine whether mutations at this locus affect the ability of bacteria to communicate within and between both species during symbiosis. Additionally, we swapped luxO between the two species to measure how luminescence is regulated, and whether it effects the type of AHL being produced in sympatry. Our results demonstrate that luxO is required for luminescence production, but additional secondary regulatory genes are responsible for luxO regulation even in a different genetic background. By understanding how different species of bacteria communicate inside an animal host will provide insight as to how symbiotic bacteria evolve cooperative mechanisms in complex beneficial associations.
