Abstract
BackgroundThis study aimed to maximize biomass concentration, biomass productivity and biochemical composition of the marine microalga Tetraselmis sp.MethodsIn the current study, Box-Behnken Design was used to model the effect of NaNO3, NaH2PO4, metals and vitamins in the F/2 medium on the growth, total chlorophylls, carotenoids and starch contents. The total chlorophylls content was quantified by spectrophotometry. The FT-IR spectroscopy was used to estimate the biochemical compositions of Tetraselmis sp. grown under both optimized medium culture for starch production and standard culture medium.ResultsFinalized NaNO3 (1.76 mM), NaH2PO4 (0.018 mM), metals (1500 μL.L−1) and vitamins (312.5 μL.L−1) concentrations, generated an increase in biomass concentration up to 5.72 g.L−1 which contributed to an increase about 2.4-fold than that of the standard conditions of biomass productivity (408.57 mg.L−1.day−1). The maximum value of carotenoids content (0.3 mg.g DW−1) was achieved at the highest level of all factors. The total chlorophylls content reached also its maximum (5.18 mg.g DW−1) at high nitrate (1.76 mM), phosphate (0.054 mM), metals and vitamins concentrations, while the maximum starch content (42% DW) was achieved with low nitrate and phosphate concentrations (0.58 mM and 0.027 mM) and with metals and vitamins limitations. Thus, the nitrogen, phosphorus, metals and vitamins limitations led to divert the metabolism for the starch biosynthesis.ConclusionsThe high biomass concentration productivity and starch production make Tetraselmis sp. strain a good candidate for biotechnological applications.
Highlights
This study aimed to maximize biomass concentration, biomass productivity and biochemical composition of the marine microalga Tetraselmis sp
No special attention has been given yet to optimize the photoautotrophic culture of this strain for biomass, production and metabolites biosynthesis using the Response Surface Methodology (RSM)
Was obtained when the concentrations of NaNO3 and NaH2PO4 decreased from 1.76 mM to 0.58 mM and from 0.054 mM to 0.027 mM, respectively, and when the volume of metal and vitamin solutions decreased from 1500 μL.L-1 to 1000 μL.L-1 and from 500 μL.L-1 to 250 μL.L-1, respectively. These results suggest that the highest starch content in Tetraselmis sp. strain V2 was obtained under nitrogen, phosphorus, metals and vitamins limitations
Summary
This study aimed to maximize biomass concentration, biomass productivity and biochemical composition of the marine microalga Tetraselmis sp. The rising crude oil prices, scarcity of fossil fuels, increasing environmental pollution due to CO2 and NOx emissions and increasing energy demand have led to look for renewable energy sources such as bioethanol, biodiesel and biohydrogen [1] In this context, microalgae were considered as one of the important sources of biofuels enjoying the advantage of accumulation of lipids (20–50% DW) and other compounds. Nutrients limitation essentially phosphorus (P) and nitrogen (N) reduces cells growth and protein synthesis and increases starch or lipid production [4]. The improvement of cultivation factors can reduce the cost of microalgae culture by reducing their nutrients consumption and maximizing their biomass and starch productions. The relationship of these products was studied under different conditions
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