RICO-MORA , R.; CARPIZO-ITUARTE, E.; PARES-SIERRA, G.; SALAS-GARZA, A.; ESCOBAR-FERNADEZ, R.; DE-LA-ROSA-VELEZ, R.; FLORES-BARRILLAS, L.; Fac. de Ciencias Marinas. UABC; Inst. de Inv. Ocean. UABC; Inst. de Inv Ocean. UABC; Inst. de Inv. Ocean. UABC; Inst. de Inv. Ocean. UABC; Fac. de Ciencias Marinas. UABC; Inst. de Inv. Ocean. UABC; : Induction to metamorphosis of two species of sea urchins in the presence microbial biofilms

It is known that different invertebrates, including echinoderms are induced to metamorphosis in the presence of microbial biofilms, presumably indicating good conditions for the new settlers. However, other than the inductive effect, little is known about the biofilm composition or its dynamic. Laboratory assays were conducted to evaluate the effect of bacterial biofilms on induction to metamorphosis of larvae of the sea urchins Strongylocentrotus purpuratus and ,Lytechinus pictus, as an initial approach to isolate the inductive bacterial strains. Biofilms used were generated by keeping multiwell plates submerged form different periods in tanks were adults of the corresponding sea urchin species were kept. The response to these biofilms was compared to biofilms generated in tanks where other invertebrates but no sea urchins were present. Induction with KCl and filtered seawater were included as positive and negative controls. Biofilms generated in the presence of adult urchins of the corresponding species were more effective, with percentages of metamorphosis as high as 95% for S. purpuratus and 91% for L. pictus. Biofilms 5 days or older were the most effective. Bacterial biofilms younger than 5 days had decreasing percentages of metamorphosis. So far, fourteen bacterial strains have been isolated from inductive biofilms. In an initial characterization all of them were gram negative and 13 with bacillus shape. Two of them fermented glucose, 64 % were oxidase positive, 78 % presented motility and 71 % need NaCl to grow.