Producción de substancias inhibitorias entre bacterias de biopelículas en substratos marinos

A study was made of antagonistic relations among benthic bacteria that form biofilms in different marine substrates. A total of 29 strains isolated from the seaweed Lessonia nigrescens and artificial substrates used for scallop (Argopecten purpuratus), and abalone (Haliotis discus hannai) larval settlement were examined for antagonistic activity against other bacteria isolated from the same substrates. Antibiosis assays of all isolates were carried out against a bacterium known to produce inhibitory substances (Vibrio C33). The results confirmed the occurrence of antagonistic interactions among microorganisms isolated from microbiota attached to the marine surfaces (20.7%). In the 329 inhibition tests, auto-inhibition activity among the selected morphotypes was not detected. L. nigrescens showed a stable bacterial population made up of four dominant strains, with one strain, a β-Proteobacteria (SL5) susceptible to the inhibitory substances produced in the same microhabitat. Inhibitory activity among the bacteria isolated from scallop collectors was observed only with one Vibrio sp. (7.7%). Evaluating the effect of strain Vibrio C33 against the 29 isolates, we detected a prominent antibacterial effect against 53.8% of the isolates from scallop settlement substrates. Inhibitory effects were not detected in antibiosis assays done on strains isolated from seaweed and abalone collectors. The phylogenetic analysis of the strains susceptible to C33 showed them all to be members of γ-Proteobacteria. Results indicate that production of inhibitory substances is a common phenomenon among bacteria isolated from bacterial biofilms, giving them a competitive advantage over other bacteria and playing an important controlling function in epiphytic microhabitats.