Mutational Analysis of c-di-GMP-Modulating Genes Reveals Complex Regulation of Motility.

The symbiont Vibrio fischeri uses motility to colonize its host. In numerous bacterial species, motility is negatively controlled by cyclic-di-GMP (c-di-GMP), which is produced by diguanylate cyclases (DGCs) with GGDEF domains and degraded by phosphodiesterases with either EAL or HD-GYP domains. To begin to decode the functions of the 50 Vibrio fischeri genes with GGDEF, EAL, and/or HD-GYP domains, we deleted each gene and assessed each mutant's migration through tryptone broth salt (TBS) soft agar medium containing or lacking magnesium (Mg) and calcium (Ca), which are known to influence V.

Quorum Sensing and Cyclic di-GMP Exert Control Over Motility of KB2B1.

Bacterial motility is critical for symbiotic colonization by of its host, the squid , facilitating movement from surface biofilms to spaces deep inside the symbiotic organ. While colonization has been studied traditionally using strain ES114, others, including KB2B1, can outcompete ES114 for colonization for a variety of reasons, including superior biofilm formation. We report here that KB2B1 also exhibits an unusual pattern of migration through a soft agar medium: whereas ES114 migrates rapidly and steadily, KB2B1 migrates slowly and then ceases migration.

Control of Competence in Vibrio fischeri.

species, including the squid symbiont , become competent to take up DNA under specific conditions. For example, becomes competent when grown in the presence of chitin oligosaccharides or upon overproduction of the competence regulatory factor TfoX. While little is known about the regulatory pathway(s) that controls competence, this microbe encodes homologs of factors that control competence in the well-studied To further develop as a genetically tractable organism, we evaluated the roles of some of these competence homologs.