Phaeobacter species are a major component of the marine bacteria and
produce an antibiotic tropodithietic acid (TDA). These bacteria also
exhibit a biphasic lifestyle alternating between a motile (by flagella)
planktonic phase and a non-motile biofilm-forming phase. Some species
exhibit probiotic activity – they block the activity of disease-causing
organisms to protect host organisms from disease. We have isolated a
Phaeobacter species that protects oysters from infection by the
bacterium Vibrio tubiashii. We are investigating the molecular basis for
probiotic activity, which may be due to TDA production and/or biofilm
formation. We have constructed several mutants that block TDA production
and others that target putative biofilm-related genes. We propose to
characterize these mutants with regard to their ability to produce TDA,
form biofilm, and protect oysters from infection from V. tubiashii. This
study will enable us to bett er understand the interactions between
probiotic, pathogenic, and host organisms.
