Complex Relationships between the Blue Pigment Marennine and Marine Bacteria of the Genus Vibrio

Abstract

Marennine, the water-soluble blue pigment produced by the marine diatom Haslea ostrearia, is known to display antibacterial activities. Previous studies have demonstrated a prophylactic effect of marennine on bivalve larvae challenged with a pathogenic Vibrio splendidus, suggesting that the blue Haslea is a good candidate for applications in aquaculture as a source of a natural antimicrobial agent. Indeed, the genus Vibrio is ubiquitous in aquaculture ecosystems, and regular events of pathogenic invasion cause some of the biggest losses worldwide. To better characterize the effects of marennine on Vibrios, a panel of 30 Vibrio strains belonging to 10 different species was tested, including bivalve pathogenic species (e.g., Vibrio crassostreae and Vibrio harveyi). Vibrio strains were first exposed to 10 and 25 µg mL−1 of Blue Water (BW), a concentrated culture supernatant of H. ostrearia containing marennine. This screening evidenced a great diversity in responses, from growth stimulation to a total inhibition, at both the interspecific or intraspecific level. In a second series of experiments, 10 Vibrio strains were exposed to BW at concentrations ranging from 5 to 80 µg mL−1. The highest concentrations of BW did not systematically result in the highest growth inhibition as hormetic responses—opposite effects regarding the concentration—were occasionally evidenced. The relationships between marennine and Vibrio strains appear more complex than expected and justify further study—in particular, on the mechanisms of action—before considering applications as a natural prophylactic or antibiotic agent in aquaculture.

Haslea silbo, A Novel Cosmopolitan Species of Blue Diatoms

“…Marennine is responsible for the greening of oyster gills in Western Europe [ 4 , 5 , 6 , 7 ]. Marennine and marennine-like pigments also display several biological activities (e.g., antibacterial, antiviral, or antioxidant) qualifying them for putative use in aquaculture and biotechnology [ 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 ].…”

Ecological and Biotechnological Aspects of Pigmented Microbes: A Way Forward in Development of Food and Pharmaceutical Grade Pigments

“…Carotenoids of archaea [ 100 ], yeasts [ 101 , 102 ], cyanobacteria, and algae [ 103 ] also function as photoprotectants. Marennine, a blue pigment produced by diatom Haslea is involved in greening on oysters [ 104 ], and displayed a prophylactic effect [ 105 , 106 ]. Food colorants, drug, dye, and other biotechnological applications of microbial pigments are detailed in the section below.…”

Electrochromic Properties and Electrochemical Behavior of Marennine, a Bioactive Blue-Green Pigment Produced by the Marine Diatom Haslea ostrearia

“…Marennine can also be considered a toxic compound for reproduction and larval stages of different marine invertebrates, but not for adults [ 13 , 14 ]. Furthermore, significant strain- and species-dependent activities against Vibrio bacteria have been evidenced [ 15 ], with possible application in aquaculture as an anti-pathogen agent [ 16 ].…”

“…The work herein presented is also linked to ongoing experiments on blue Haslea cells carried out to have a better understanding of the microalgae physiology. These results will help in clarifying the role of the pigment and the reasons why Haslea cells produce it, as there is still a debate about its intrinsic utility for self-defense because of the allelopathic [ 8 , 11 ], antiviral, and antibacterial properties [ 10 , 15 ], or for a “sunscreen” protection against solar radiation due to UV absorption.…”