Abstract
BackgroundMicroalgae are well-established feedstocks for applications ranging from biofuels to valuable pigments and therapeutic proteins. However, the low biomass productivity using commercially available growth mediums is a roadblock for its mass production. This work describes a strategy to boost algal biomass productivity by using an effective CO2 supplement.ResultsIn the present study, a novel nanoemulsion-based media has been tested for the growth of freshwater microalgae strain Chlorella pyrenoidosa. Two different nanoemulsion-based media were developed using 1% silicone oil nanoemulsion (1% SE) and 1% paraffin oil nanoemulsion (1% PE) supplemented in Blue-green 11 media (BG11). After 12 days of cultivation, biomass yield was found highest in 1% PE followed by 1% SE and control, i.e., 3.20, 2.75, and 1.03 g L−1, respectively. The chlorophyll-a synthesis was improved by 76% in 1% SE and 53% in 1% PE compared with control. The respective microalgal cell numbers for 1% PE, 1% SE and control measured using the cell counter were 3.00 × 106, 2.40 × 106, and 1.34 × 106 cells mL−1. The effective CO2 absorption tendency of the emulsion was highlighted as the key mechanism for enhanced algal growth and biomass production. On the biochemical characterization of the produced biomass, it was found that the nanoemulsion-cultivated C. pyrenoidosa had increased lipid (1% PE = 26.80%, 1% SE = 23.60%) and carbohydrates (1% PE = 17.20%, 1% SE = 18.90%) content compared to the control (lipid = 18.05%, carbohydrates = 13.60%).ConclusionsThis study describes a novel nanoemulsion which potentially acts as an effective CO2 supplement for microalgal growth media thereby increasing the growth of microalgal cells. Further, nanoemulsion-cultivated microalgal biomass depicts an increase in lipid and carbohydrate content. The approach provides high microalgal biomass productivity without altering morphological characteristics like cell shape and size as revealed by field emission scanning electron microscope (FESEM) images.Graphical abstract
Highlights
Microalgae are well-established feedstocks for applications ranging from biofuels to valuable pigments and therapeutic proteins
The average droplet size observed in 1% 1% Silicone oil nanoemulsion (SE) was in the range of ~ 244 nm to 285 nm and ~ 164 nm to 297 nm in 1% 1% Paraffin oil nanoemulsion (PE)
The result indicated that the larger droplet size, greater than a micron has been separated from the emulsion
Summary
Microalgae are well-established feedstocks for applications ranging from biofuels to valuable pigments and therapeutic proteins. The low biomass productivity using commercially available growth mediums is a roadblock for its mass production. This work describes a strategy to boost algal biomass productivity by using an effective CO2 supplement. There have been various attempts to enhance algal biomass production and specific biomolecule content by providing algal growth supplements, phytohormones or optimizing the N/P ratio [3, 4]. Renuka et al [7] studied the effect of exogenous cytokinins on microalgae under nitrogen stress and obtained high biomass (176.79 mg L−1 d−1) as well as lipid productivity (63.14 mg L−1 d−1) of Acutodesmus obliquus on the addition of zeatin. The biomass and lipid productivities were enhanced by 23.4% and 60%, respectively, compared with conventional BG11
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