Combining glucose and sodium acetate improves the growth of Neochloris oleoabundans under mixotrophic conditions.

Helder Rodrigues Silva,Diva Souza Andrade,Victor Hugo De Mello,Freddy Zambrano,Cesar Augusto Tischer,Cassio Egidio Cavenaghi Prete

doi:10.1186/s13568-016-0180-5

Abstract

Mixotrophic cultivation is a potential approach to produce microalgal biomass that can be used as raw materials for renewable biofuels and animal feed, although using a suitable, cost-effective organic carbon source is crucial. Here, we used a Box–Behnken design with three factors, the glucose and sodium acetate concentrations, and the percentage of Bold’s basal medium (BBM), to evaluate the effects of different carbon sources on biomass productivity and the protein and lipid contents of Neochloris oleoabundans (UTEX#1185). When grow at optimal levels of these factors, 100 % BBM plus 7.5 g L−1 each of glucose and sodium acetate, N. oleoabundans yielded 1.75 g L−1 of dry biomass, with 4.88 ± 0.09 % N, 24.01 ± 0.29–30.5 ± 0.38 % protein, and 34.4 % ± 0.81 lipids. A nuclear magnetic resonance spectrum (1H-NMR) of a lipid extract showed that the free fatty acid content was 11.25 %. Thus, combining glucose and sodium acetate during the mixotrophic cultivation of N. oleoabundans can yield greater amounts of biomass, proteins, and lipids for biofuel production.

Highlights

Increasing use of oil-derived energy has generated negative environmental effects such as pollution and greenhouse gas emissions
The variables studied had significant (p < 0.01) effects on the dry biomass of N. oleoabundans, and the highest value was 1.4 g L−1, which was obtained on day 10 of cultivation (Fig. 1a, b)
The analysis of the means of dry biomass production (g L−1) assayed on d 10 of cultivation was influenced by a combination of the concentrations of glucose and sodium acetate in the medium, as well as by the % Bold’s basal medium (BBM) (Fig. 1a)

Summary

Introduction

Increasing use of oil-derived energy has generated negative environmental effects such as pollution and greenhouse gas emissions. In addition to their great potential for bioenergy production, some species of microalgae are already used in aquaculture, the production of food supplements, and the pharmaceutical industry to extract high-value compounds (Gatenby et al 2003), as well as in bioremediation and biofertilization. A mixotrophic system combines the advantages of phototrophic and heterotrophic cultures (Li et al 2014), and obtains energy from organic and inorganic carbon sources, as well as light. Microalgal cultures produce more biomass (Babuskin et al 2014), including higher amounts of pigments and fatty acids, than phototrophic systems (Alkhamis and Qin 2015)

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