Adhesion ability to coral mucus of isolated bacteria from Pocillopora sp. and Porites panamensis of California Gulf southeast

Abstract

El estudio de la microbiota en corales es de fundamental importancia para un mejor entendimiento de los procesos que determinan su asociación con el holobionte, sin embargo, aún se conoce poco acerca de los mecanismos básicos de dicha asociación. En esta investigación el objetivo fue aislar a partir de corales sin signos aparentes de enfermedad, las bacterias predominantes de la comunidad, determinar su capacidad de adhesión al moco producido por Pocillopora sp. e identificarlas molecularmente. Se recolectaron corales de los géneros Pocillopora sp. y P. panamensis, se cuantificó la población de cuatro grupos de microorganismos (expresados como Log de UFC g-1): bacterias mesófilas aerobias (4.7 - 6.4), bacterias ácido lácticas (˂1.0-5.8), bacterias del género Vibrio (˂1.0-4.5), así como hongos y levaduras (˂1.0-3.6). Se aislaron 156 cepas bacterianas del holobionte homogeneizado y se seleccionaron aquellas con mayor crecimiento a las 24 h para el ensayo de adhesión, que consistió en 25 cepas de Pocillopora sp. y 27 de Porites panamensis. El ensayo de adhesión al extracto crudo de moco de Pocillopora sp., marcado enzimáticamente con HRP mostró que el 82 % de las cepas se adhieren. Se extrajo ADN de todas las cepas, sin embargo, con los oligonucleótidos universales utilizados se obtuvieron productos de PCR solo de 32. Se identificaron molecularmente 14 de Pocillopora sp. y 18 de P. panamensis con base en la secuenciación y análisis del gen 16S DNAr. Las cepas identificadas correspondieron a 17 especies, donde predominó el género Bacillus, con 64 % en Pocillopora sp. y 44 % en P. panamensis. Las especies de bacterias que comparten estos corales son B. subtilis y Staphylococcus hominis. Se sugiere que las especies identificadas adherentes tienen la capacidad de colonizar el moco del coral, son comensales y potencialmente benéficas, debido a que fueron aisladas de corales aparentemente sanos. Adhesion ability to coral mucus of isolated bacteria from Pocillopora sp. and Porites panamensis of California Gulf southeast ABSTRACT. The study of coral microbiota is of fundamental importance for a better understanding of the processes that determine its association with the holobiont, however, little is known about the basic mechanisms of this association. In this research, the objective was to isolate from corals without apparent signs of disease, the predominant bacteria of the community, determine their ability to adhere to the mucus produced by Pocillopora sp. and identify them molecularly. Corals of the genera Pocillopora sp. and Porites panamensis were recollected, the population of four groups of microorganisms (expressed as Log of CFU g-1) was quantified. Results indicated aerobic mesophilic bacteria (4.7 - 6.4), lactic acid bacteria (˂1.0-5.8), bacteria of the Vibrio genus (˂ 1.0-4.5), as well as fungi and yeasts (˂1.0-3.6). 156 bacterial strains of the homogenized holobiont were isolated and those with the highest growth at 24 h were selected for the adhesion test, which consisted of 25 strains of Pocillopora sp. and 27 of P. panamensis. The adhesion test to the enzymatically labeled with HRP crude mucus extract of Pocillopora sp., showed that 82% of the strains adhere. DNA was extracted from all strains, however, with the universal oligonucleotides used, only 32 PCR products were obtained. 14 strains from Pocillopora sp. and 18 from P. panamensis were molecularly identified based on the sequencing and analysis of the 16S DNAr gene. The strains identified corresponded to 17 species, where the genus Bacillus predominated, with 64% in Pocillopora sp. and 44% in P. panamensis. The species of bacteria that share these corals are B. subtilis and Staphylococcus hominis. It is suggested that the identified adherent species have the ability to colonize coral mucus, are commensal and potentially beneficial, because they were isolated from apparently healthy corals.