Seaweed produces metabolites aiding in the protection against different environmental stresses. These compounds show antiviral, antiprotozoal, antifungal, and antibacterial properties. Macroalgae can be cultured in high volumes and would represent an attractive source of potential compounds useful for unconventional drugs able to control new diseases or multiresistant strains of pathogenic microorganisms. The substances isolated from green, brown and red algae showing potent antimicrobial activity belong to polysaccharides, fatty acids, phlorotannins, pigments, lectins, alkaloids, terpenoids and halogenated compounds. This review presents the major compounds found in macroalga showing antimicrobial activities and their most promising applications.

Aim: The aim of the present study was to clarify the taxonomic status of Vibrio strains isolated from an aquaculture system and to compare the results of the identifications made by phenotypic and mo...

The aim of this study was to evaluate the survival responses of two strains of Vibrio splendidus, both in natural and in defined media. For this purpose, freshwater and defined media containing different salinities (3·3–0·9 %) and nutrient concentrations (17–0·005 mg l⁻¹) were assayed. The incubation temperatures were established at 4, 10 and 22 °C. The acridine orange staining technique was used for total cell enumeration and the number of viable cells was determined using two direct assays, nalidixic acid and tetrazolium salt reduction and plate spreading. Resuscitation assays of viable but non-culturable (VBNC) cells were conducted. According to the counting procedures employed, at least four different subpopulations were found: (i) active (positive response in both nalidixic acid and tetrazolium assays) culturable cells; (ii) active non-culturable cells; (iii) tetrazolium-salt-responsive non-culturable cells and (iv) non-active (responsive to none of the direct viable assays) non-culturable cells. Long-term survival was found at salinities and nutrient concentrations of seawater environments (3·3 % and 5 mg l⁻¹ or 1 g l⁻¹), whereas the strains entered a VBNC state in freshwater and in brackish (0·9 or 1·6 % salinities) or high nutrient content (17 g l⁻¹) defined medium. The recovery of VBNC cells was not achieved.