Vibrio campbellii suppressor mutant strains isolated in minimal media

This study evaluated the role of quorum sensing genes in growth under varying nutrient conditions in the aquaculture pathogen Vibrio campbellii. Bacteria sense population density via the cell-cell communication system called quorum sensing (QS). Some QS-regulated phenotypes (e.g., secreted enzymes, chelators), are public goods exploitable by cells that stop producing them. We uncovered a phenomenon in which Vibrio cells optimize expression of the methionine and tetrahydrofolate (THF) synthesis genes via QS. Strains that are genetically 'locked' at high cell density grow slowly in minimal glucose media and suppressor mutants accumulate via inactivating mutations in metF (methylenetetrahydrofolate reductase) and luxR (the master QS transcriptional regulator).