Meeting Abstract
Larvae of the serpulid polychaete Hydroides elegans can be induced to metamorphose by monospecific biofilms of a number of bacterial species. Detailed investigations into the nature of the settlement cue produced by the bacterium Pseudoalteromonas luteoviolacea have established bacteriocin aggregates (or MACs) as the metamorphic cue by this bacterium. In our study, three additional inductive bacterial species, Cellulophaga lytica, Bacillus aquimarus and Staphylococcus warneri, were investigated to determine if they produce similar products. Genomic comparisons of these bacteria revealed that their metamorphic activities are not due to the presence of the same genetic machinery as P. luteoviolacea. Active biofilm cell densities differed between the strains and metamorphic activity was found in the 0.22 μm filtrate in direct contrast to MACs of P. luteoviolacea. In C. lytica, negatively stained TEM images confirmed the lack of MAC structures and instead revealed the presence of vesicles. Further TEM imaging confirmed that these vesicles budded from the surface of C. lytica in a manner consistent with outer membrane vesicles. Equivalent TEM analyses of S. warneri, however, did not reveal the presence of either MACs or vesicles. It is likely that the ability of H. elegans to respond to multiple bacterial biofilm products greatly increases its larva’s ability to find and settle on appropriate surfaces with differing bacterial communities.
