Marine sponges play a fundamental role in the proper functioning of the ecosystem by filtering organic matter and contributing to nutrient fluxes. These animals have been proposed as efficient bioremediators of microbiological contamination in various environmental conditions subjected by anthropogenic pressure. In the present study, the bioremediation potential of the demosponges Aplysina aerophoba and Geodia cydonium was analyzed ex situ. For this purpose, the viable count of an antibiotic-resistant bacterial strain belonging to the species Vibrio parahaemolyticus was assessed in presence of the selected sponge species. Although some sponge individuals showed closed oscula during the first hours of the experiment, A. aerophoba and G. cydonium reduced the bacterial load in the seawater up to five orders of magnitude in 72 h. In addition, they had high clearance rates and retention efficiencies, with almost complete removal of the tested bacteria. Low Vibrio concentrations were observed in all tanks after six days, suggesting no excretion of viable Vibrio from sponges. These results corroborate the usefulness of A. aerophoba and G. cydonium as bioremediators of bacteria and therefore appear to be ideal candidates for bioremediation purposes in anthropogenic environments, such as aquaculture facilities, where multidrug-resistant bacteria may play a role in the spread of antimicrobial resistance.
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