Morphological Heterogeneity and Attachment of <i>Phaeobacter inhibens</i>

<div><p>The Roseobacter clade is a key group of bacteria in the ocean exhibiting diverse metabolic repertoires and a wide range of symbiotic life-styles. Many Roseobacters possess remarkable capabilities of attachment to both biotic and abiotic surfaces. When attached to each other, these bacteria form multi-cellular structures called rosettes. <i>Phaeobacter inhibens</i>, a well-studied Roseobacter, exhibits various cell sizes and morphologies that are either associated with rosettes or occur as single cells. Here we describe the distribution of <i>P</i>. <i>inhibens</i> morphologies and rosettes within a population. We detect an N-acetylglucosamine-containing polysaccharide on the poles of some cells and at the center of all rosettes. We demonstrate that rosettes are formed by the attachment of individual cells at the polysaccharide-containing pole rather than by cell division. Finally, we show that <i>P</i>. <i>inhibens</i> attachment to abiotic surfaces is hindered by the presence of DNA from itself, but not from other bacteria. Taken together, our findings demonstrate that cell adhesiveness is likely to play a significant role in the life cycle of <i>P</i>. <i>inhibens</i> as well as other Roseobacters.</p>