Coupled effect of silicate and nickel on the growth and lipid production in the diatom Nitzschia perspicua

Abstract

The object of this study was to determine the growth rate and biochemical composition of the diatom Nitzschia perspicua cultivated with five Si and two Ni concentrations (which we will refer to as treatments) during a “growth” and “lipid” phase (GP and LP). The studies multi-factorial experimental design will provide information on the biochemistry of lipid accumulation under Si-replete and Si-deficient conditions in media and with high and low Ni concentrations. Growth rates ranged from 0.14 to 0.24 day−1 during GP; they were higher in the low rather than high Ni treatments but did not vary in response to Si between 0.2 and 10.6 mmol m−3. Dry weights were higher when N. perspicua was grown in the LP than those in the GP (irrespective of Ni or Si treatment; with two exceptions). When comparing the same Si treatment, high Ni cultures had higher biomass (C% of dry weight (DW)) than low Ni cultures. High Si treatments generally had significantly lower N% content in both GP and LP. Fourier transform infrared spectroscopy revealed that high Ni in the medium induced higher lipid, protein, and polysaccharide contents regardless of the Si concentration during the GP. After being transferred to LP, cultures grown in lower Si concentrations generally accumulated more lipids than those grown at higher Si, consistent with findings from the oil index. The work described herein provides a better understanding of the biochemistry of lipid accumulation of a representative diatom, N. perspicua, with a range of Si and Ni concentrations.