Growth Kinetic and Biodiesel Lipid Extraction of Nannochloropsis oculata Microalgae in a Photobioreactor under Varying Salinity Conditions

Abstract

Microalgae are microorganisms that have become protagonists in research in recent years because they are potential candidates for use in obtaining compounds of interest such as lipids, which may be transformed into bioenergy compounds like biodiesel. Nannochloropsis oculata is a marine microalga whose main characteristic is its high lipid content. In this work, the effect of salinity intensity on the growth of N. oculata was investigated in the photobioreactor batch cultures incubated with a salinity ranging from 20 to 40 ppt to analyze its growth profile and chlorophyll pigment to obtain dry biomass and biofuel produced as lipid extraction. The results indicated specific growth rate maximum values of 0.343 day-1, obtained at 35 ppt salinity. Chlorophyll pigment increases with salt concentration between 25 and 35 ppt. The total lipid extracted increases considerably at moderate salinities condition (25-35) ppt, the maximum dry biomass harvest and productivity, accomplished after the microalgae cultivation salinity at 30 ppt was 0.623 g/l and 62.3 mg/l respectively. The same applies to the maximum total lipid content and productivity, 221 mg/l and 22.1 mg/l. day, respectively. These findings show that various salinities support optimal biomass yield and biochemical composition in N. oculata cultivation. Salinity monitoring is crucial for successful cultivation. Furthermore, the advantages of N. oculata microalga, including its large cell size (facilitating harvest and grazer tolerance) and its salinity resilience, should be considered

Keywords

• biomass
• biofuel
• lipid production
• chlorophyll pigment
• specific growth