Background: Microalgae 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 the algal biomass productivity by using an effective CO 2 supplement.
Results: In 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 BG11 media During 12-day growth experiment, the 1% PE gave the highest biomass yield (3.2± 0.07gL -1 ), followed by 1%SE (2.75 ± 0.07 gL -1 ) and control (1.03±0.02 gL -1 ). The respective microalgal cell number measured using cell counter were (3.0 ± 0.21 x 10 6 cells ml -1 ), (2.4 ± 0.30 x 10 6 cells ml -1 ) and (1.34 ± 0.09 x 10 6 cells ml -1 ). Cell viability analysis using MTT assay showed that 1% PE also had higher viable cells (94%) compared to 1% SE (77%) and control (53%). The effective CO 2 absorption tendency of the emulsion was highlighted as the key mechanism for greater biomass production. On the biochemical characterization of the produced biomass, it was found that the nanoemulsion cultivated C. pyrenoidosa had increased lipid (1% PE=26.8%, 1% SE=23.6%) and carbohydrates (1% PE=17.2%, 1% SE=18.9%) content compared to the control (lipid=18.05%, carbohydrates=13.6%).
Conclusions: This study provides a novel nanoemulsion which acts as an effective CO 2 supplement for microalgal growth media which increase the growth of microalgal cells. Importantly, nanoemulsions cultivated microalgal biomass possess increment in lipid and carbohydrate content. This approach also provides high microalgal biomass productivity without alteration of morphological characteristics like cell shape and cell size.