Antimicrobial Compounds from Eukaryotic Microalgae against Human Pathogens and Diseases in Aquaculture

Abstract

The search for novel compounds of marine origin has increased in the last decades for their application in various areas such as pharmaceutical, human or animal nutrition, cosmetics or bioenergy. In this context of blue technology development, microalgae are of particular interest due to their immense biodiversity and their relatively simple growth needs. In this review, we discuss about the promising use of microalgae and microalgal compounds as sources of natural antibiotics against human pathogens but also about their potential to limit microbial infections in aquaculture. An alternative to conventional antibiotics is needed as the microbial resistance to these drugs is increasing in humans and animals. Furthermore, using natural antibiotics for livestock could meet the consumer demand to avoid chemicals in food, would support a sustainable aquaculture and present the advantage of being environmentally friendly. Using natural and renewable microalgal compounds is still in its early days, but considering the important research development and rapid improvement in culture, extraction and purification processes, the valorization of microalgae will surely extend in the future.

Disinfection and nutrient removal in laboratory‐scale photobioreactors for wastewater tertiary treatment

“…In the continuous growth test a positive correlation was observed between the E. coli LUR and algal density similarly to other studies conducted in eutrophic lake and in a continuous flow PBR fed on effluent from an up‐flow anaerobic sludge blanket reactor and operated with different dilution rates . As the pH of the PBR was controlled by CO 2 sparging, it could not contribute to the bacterial abatement, while the increase of dissolved oxygen concentration (up to 20 mg L −1 ) and the probable release of secondary metabolites such as such as fatty acids terpenoids, carbohydrates, peptides, polysaccharides and alkaloids by the microalgae might have an effect on the inactivation of E. coli . Even though these antimicrobial compounds were not analysed in the study, Chlorella sp.…”

“…and Scenedesmus sp., the dominant species detected in the PBR, are known to have potent antibacterial activity against both Gram-positive and Gram-negative bacteria. 33,35 The disinfection efficiency of the microalgae-based process was also confirmed by the PCR-based analyses, which demonstrated that the numbers of all tested pathogenic and faecal indicator strains were below the detection limit (2 log cell eq. 100 mL −1 ) in the samples collected from the microalgal suspensions.…”

“…Even though these antimicrobial compounds were not analysed in the study, Chlorella sp. and Scenedesmus sp., the dominant species detected in the PBR, are known to have potent antibacterial activity against both Gram‐positive and Gram‐negative bacteria …”

“…14,29 As the pH of the PBR was controlled by CO 2 sparging, it could not contribute to the bacterial abatement, while the increase of dissolved oxygen concentration (up to 20 mg L −1 ) and the probable release of secondary metabolites such as such as fatty acids terpenoids, carbohydrates, peptides, polysaccharides and alkaloids by the microalgae might have an effect on the inactivation of E. coli. 16,33,34 Even though these antimicrobial compounds were not analysed in the study, Chlorella sp. and Scenedesmus sp., the dominant species detected in the PBR, are known to have potent antibacterial activity against both Gram-positive and Gram-negative bacteria.…”

Tetraselmis suecica F&M‐M33 growth is influenced by its associated bacteria

“…Besides algae releasing stimulatory substances (Terekhova et al, 2009;Natrah et al, 2014), there are many able to produce bactericidal or bacteriostatic compounds . These latter are of huge biotechnological interest in the search for new antibiotics (Senhorinho et al, 2015;Falaise et al, 2016).…”