Simultaneous production assessment of riacylaglycerols for biodiesel and exopolysaccharides as valuable co-products in Navicula cincta

CECILIA A. POPOVICH; LUCAS A. MARTIN; GUADALUPE BARNECH BIELSA; ANA M. MARTÍNEZ; PATRICIA I. LEONARDI; MARIA CECILIA RODRÍGUEZ; MARÍA C, MATULEWICZ

Algal Research

Elsevier B:V:

Año: 2016 vol. 15 p. 120 - 128

The marine benthic diatom Naviculacincta was cultured in order to evaluate its capacity to produce bothneutral lipid-triacylglycerols (TAG) for biodiesel, and exopolysaccharides(EPS), as valuable co-products, under the same environmental conditions. Thespecies was cultured without applying stress conditions, except for the onesnaturally created by the culture age. Peaks of neutral lipid accumulation wereestimated by fluorimetry by Nile Red. Consequently, lipids were extracted andfractionated into neutral and polar fractions and the fatty acid profile of eachfraction analysed by GC. The stationary phase began on day 6, when phosphateand silicate reached limiting values for diatom growth. Total lipids and lipidfractions did not show differences between harvesting time points, reachingtotal lipid up to 41% of ash-free dry weight (AFDW) and TAG the dominantfraction (ca. 90%of total lipids). Particularly noticeable was the storage ofpalmitoleic acid (ca. 54% of total fatty acidmethyl esters) and a lower levelof polyunsaturated fatty acids, which may impart overall favourable propertiesto a biodiesel fuel, especially cold flow and oxidative stability. The maximumconcentrations of EPS corresponded to soluble fraction, which was most significantwhen the cultures reached the stationary phase and when the medium was almostphosphate and silicate depleted. The characterization of soluble EPS indicatedthe presence of N-glycopeptides. According to the present results, a hypotheticalscheme of demonstrative cultures under a biorefinery approach is proposed for N. cincta.