Characterization and Biotechnological Potential of Two Native Marine Microalgae Isolated from the Tunisian Coast

Jamila Ben Mohamed,Maria Ángeles Esteban,Jihen Elleuch,Imen Fendri,Slim Abdelkafi,Philippe Michaud,Marwa Drira

doi:10.3390/app11115295

Abstract

Microalgae are attracting considerable interest worldwide. In the present study, two native microalgae strains isolated from Tunisian cost were identified as Chlamydomonas sp. and Navicula sp. We characterized their pigment and protein contents, as well as their carbohydrate and lipid productivity. The predominant fatty acids were found to be α-linolenic acid (C18:3n-3) and palmitoleic acid (C16:1n-7) for Chlamydomonas sp. and Navicula sp. strains respectively. Microalgae methanol extracts showed important in vitro antibacterial activity against all tested gram negative bacteria. Antioxidant activities of methanol extracts were investigated by determining radical scavenging activity according to DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) methods. MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay showed that the newly isolated microalgae were not toxic and have potential application in the fish feeds domain as a supplement in fish meal. Also, the biosorption of cadmium from aqueous solutions by microalgae living cells was evaluated. Large removal capacities were obtained with values ranging from 89.8% to 99.38%. These results are very promising as a starting point for a potential application of these new isolates for in situ bioremediation of heavy metals contaminating aqueous systems.

Highlights

Microalgae comprise a vast group of both marine and freshwater habitats organisms.Based on DNA sequence data, they have been classified into ten major phyta which are Glaucophyta, Euglenophyta, Cryptophyta, Haptophyta, Dinophyta, Heterocontophyta, Rhodophyta, Chlorophyta, and the prokaryotic Cyanophyta [1]
A focus has been shifted towards these organisms due to their diverse metabolic contents. They synthesize a large number of bioactive compounds, including pigments, sterols, polyphenols, fatty acids, proteins, vitamins, alkaloids, and sulfated polysaccharides with various chemical structures and biological activities [2,3]
Two microalgae strains MAa1 and MAn1 were isolated from seawater of Tunisia costs and molecularly identified as Chlamydomonas sp. and Navicula sp., respectively

Summary

Introduction

Microalgae comprise a vast group of both marine and freshwater habitats organisms.Based on DNA sequence data, they have been classified into ten major phyta which are Glaucophyta, Euglenophyta, Cryptophyta, Haptophyta, Dinophyta, Heterocontophyta (including diatoms), Rhodophyta, Chlorophyta, and the prokaryotic Cyanophyta (cyanobacteria) [1]. A focus has been shifted towards these organisms due to their diverse metabolic contents They synthesize a large number of bioactive compounds, including pigments, sterols, polyphenols, fatty acids, proteins, vitamins, alkaloids, and sulfated polysaccharides with various chemical structures and biological activities [2,3]. These biomolecules are useful for microalgal-based feed and food, nutraceutical, pharmaceutical, and cosmetic industries through their antioxidant, antifungal, antibacterial, antiviral, antienzymatic, anti-cancer, or anti-inflammatory activities [4,5,6,7]. Due to their rich nutritional properties, some Chlorophycae and diatoms genera have been widely used as dietary supplements for both humans and animals [10,11]

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