Meeting Abstract

111-3  Sunday, Jan. 7 08:45 – 09:00  Bacterial induction of metamorphosis of Hydroides elegans (Polychaeta): A new twist in the tailocin tale NEDVED, BT*; FRECKELTON, ML; HADFIELD, MG; Kewalo Marine Laboratory, University of Hawaiʻi at Mānoa; Kewalo Marine Laboratory, University of Hawaiʻi at Mānoa; Kewalo Marine Laboratory, University of Hawaiʻi at Mānoa nedved@hawaii.edu

Phage-tail bacteriocins (tailocins) produced by the marine bacterium Pseudoalteromonas luteoviolacea, are encoded by a cassette of ten genes within the bacterial genome, and bacteria expressing these proteins rapidly induce larvae of the serpulid polychaete Hydroides elegans to metamorphose. Extensive research has demonstrated that six of these genes are required to generate an inductive cue by the HI1 strain of P. luteoviolacea. These genes (macS, macT1, macT2, MacB, ORF2, and ORF3) are also present in the genomes of several other strains of P. luteoviolacea, including the type strain (ATCC 3492). Further, we have used rtPCR to demonstrate that phage-tail bacteriocins are also expressed by the ATTC strain under normal culture conditions. However, monospecific biofilms of this strain do not induce metamorphosis of H. elegans. These data suggest that more than tailocins are necessary to induce metamorphosis. New experimental data indicate that outer membrane vesicles (OMVs) are also involved. Other species of inductive bacteria produce OMVs but not tailocins. We have used gradient ultracentrifugation to isolate and purify OMVs from P. luteoviolacea (strain HI) and found that they induce metamorphosis. It is now clear that the mechanism for induction of metamorphosis from P. luteoviolacea is not as straightforward as originally thought. It appears that OMVs form a second, concurrent mechanism of induction by HI1 strain.