title: Enhanced lipid and biomass production by a newly isolated and identified marine microalga.
abstract: BACKGROUND
  The increasing demand for microalgae lipids as an alternative to fish has encouraged researchers to explore oleaginous microalgae for food uses. In this context, optimization of growth and lipid production by the marine oleaginous V2-strain-microalgae is of great interest as it contains large amounts of mono-unsaturated (MUFAs) and poly-unsaturated fatty acids (PUFAs).
  
  
  METHODS
  In this study, the isolated V2strain was identified based on 23S rRNA gene. Growth and lipid production conditions were optimized by using the response surface methodology in order to maximize its cell growth and lipid content that was quantified by both flow cytometry and the gravimetric method. The intracellular lipid bodies were detected after staining with Nile red by epifluorescence microscopy. The fatty acid profile of optimal culture conditions was determined by gas chromatography coupled to a flame ionization detector.
  
  
  RESULTS
  The phenotypic and phylogenetic analyses showed that the strain V2was affiliated to Tetraselmis genus. The marine microalga is known as an interesting oleaginous species according to its high lipid production and its fatty acid composition. The optimization process showed that maximum cell abundance was achieved under the following conditions: pH: 7, salinity: 30 and photosynthetic light intensity (PAR): 133 μmol photons.m-2.s-1. In addition, the highest lipid content (49 ± 2.1% dry weight) was obtained at pH: 7, salinity: 37.23 and photosynthetic light intensity (PAR): 188 μmol photons.m-2.s-1. The fatty acid profile revealed the presence of 39.2% and 16.1% of total fatty acids of mono-unsaturated fatty acids (MUFAs) and poly-unsaturated fatty acids (PUFAs), respectively. Omega 3 (ω3), omega 6 (ω6) and omega 9 (ω9) represented 5.28%, 8.12% and 32.8% of total fatty acids, respectively.
  
  
  CONCLUSIONS
  This study showed the successful optimization of salinity, light intensity and pH for highest growth, lipid production and a good fatty acid composition, making strain V2highly suitable for food and nutraceutical applications.
authors.affiliation: Biotechnologie des Algues, Biological Engineering Department, National School of Engineers of Sfax, University of Sfax, Sfax, Tunisia.
authors.forename: Mouna
authors.initials: M
authors.lastname: Dammak
authors.affiliation: Institute of Horticultural Production Systems, Section Biosystems Engineering, Leibniz University Hannover, Herrenhauser Str. 2, 30419, Hannover, Germany.
authors.forename: Sandra Mareike
authors.initials: SM
authors.lastname: Haase
authors.affiliation: Biotechnologie des Algues, Biological Engineering Department, National School of Engineers of Sfax, University of Sfax, Sfax, Tunisia.
authors.forename: Ramzi
authors.initials: R
authors.lastname: Miladi
authors.affiliation: Biotechnologie des Algues, Biological Engineering Department, National School of Engineers of Sfax, University of Sfax, Sfax, Tunisia.
authors.forename: Faten
authors.initials: F
authors.lastname: Ben Amor
authors.affiliation: Biotechnologie des Algues, Biological Engineering Department, National School of Engineers of Sfax, University of Sfax, Sfax, Tunisia.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Barkallah
authors.affiliation: Center for Molecular Biophysics (CBM), CNRS UPR4301, Orléans, France.
authors.forename: David
authors.initials: D
authors.lastname: Gosset
authors.affiliation: Center for Molecular Biophysics (CBM), CNRS UPR4301, Orléans, France.
authors.forename: Chantal
authors.initials: C
authors.lastname: Pichon
authors.affiliation: Institute of Botany, Leibniz Universitaet Hannover, Herrenhauser Str. 2, 30419, Hannover, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Huchzermeyer
authors.affiliation: Unit Research of Toxicology-Microbiology Environmental and Health UR11ES70, Faculty of Sciences of Sfax, University of Sfax, Sfax, Tunisia.
authors.forename: Imen
authors.initials: I
authors.lastname: Fendri
authors.affiliation: Aix Marseille Université, Université de Toulon, CNRS/INSU, IRD, Institut Méditerranéen d'Océanologie (MIO), 163 avenue de Luminy, Case 901, 13288, Marseille Cedex 09, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Denis
authors.affiliation: Biotechnologie des Algues, Biological Engineering Department, National School of Engineers of Sfax, University of Sfax, Sfax, Tunisia. slim.abdelkafi@enis.tn.
authors.forename: Slim
authors.initials: S
authors.lastname: Abdelkafi
mesh_terms: D018533:Biomass; D000460:Chlorophyta / Q000737:chemistry*; D005227:Fatty Acids / Q000032:analysis / Q000302:isolation & purification*; D005410:Flame Ionization; D058086:Microalgae / Q000737:chemistry
chemical_list: D005227:Fatty Acids
keywords: Flow cytometry; Lipids; Microalgae; Poly-unsaturated fatty acids; Response surface methodology; Tetraselmis sp.