Bioatividade de extratos de algas frente à bactérias com fatores de virulência, resistentes a antimicrobianos

Abstract

Infection of aquatic organisms by Vibrios can lead to serious economic losses for farmers and expose consumers to serious health risks. Some Vibrio species carry factors of virulence making them potentially pathogenic to humans. The consequent widepread use of antibiotics by farmers has led to the selection of resistant strains in the environment. Due to the increasing incidence of bacteria resistant to antibiotics, much effort is currently invested in identifying natural products with bioactive potential. Macroalgae have been studied for their ample spectrum of biological, antioxidant, antifungal and agglutinating activities. The purpose of this study was to evaluate the antibacterial activity of hexane, methanol, acetone and ethanol-based extracts of Chlorophyta, Phaeophyta and Rhodophyta macroalgae against virulent víbrio strains resistant to antibiotics. The microorganisms used in the study included víbrio strains isolated from wild oysters purchased at a fish market, strains from shrimp hemolymph and the standard strains ATCC and IOC. The strains were challenged with extracts using the disk diffusion method. Ethanol was the most efficient solvent. Padina gymnospora inhibited the largest number of Vibrio species (57%) and produced the largest inhibition halos, followed by Ulva fasciata (40%) and Hypnea musciformes (30%). The smallest minimum inhibitory concentration was observed for ethanolic extracts of Padina gymnospora (512 μg/mL against Vibrio alginolyticus). The results suggest extracts of marine macroalgae may represent a potential source of natural biologically active products for use in the industry.