Effect of various substrate conditions on the microalgal production of lipid

Abstract

Globally, our demand for energy is ever increasing while the sources we have depended on the last few centuries have become scarcer and will get depleted in the near future. Developing new strategies for biofuel production as a renewable energy is gaining importance. Biodiesel is a non-toxic alternative fuel that is obtained from renewable sources. Microalgae as a feed stock for biofuels have obvious advantages such as rapid growth rate, high lipid content and also mitigation of CO2. Moreover, microalgae can efficiently uptake nitrogen and phosphorus, which offers an economic and eco-friendly approach of using wastewaters for microalgal cultivation with simultaneous removal of inorganic nutrients. Various factors such as nutrients and salinity affect the biochemical properties of algae. Algal cultures become depleted of nutrients, when they reach stationary stages of their growth, and an increase in the total lipid is observed at this stage. In the present study, effect of various micronutrients (Co, Mn, Zn and Cu) on biomass production and lipid productivity of Micractinium pusillum cultivated in the Bold Basal Media (BBM) was investigated. In the BBM control, M. pusillum showed a biomass production and lipid productivity of 0.79±0.05 and 0.32±0.02 g/L, respectively. The biomass production increased to 1.25±0.01 and 1.28±0.01 g /L while the lipid productivity to 0.45±0.04 and 0.47±0.05 g/L, when cultivated in BBM with 4X Mn and Cu. The effect of salinity (NaCl) on the nutrient removal, algal growth, lipid productivity of Chlamydomonas mexicana cultivated in municipal wastewater was also studied. Total Nitrogen was completely removed by the addition of 200-400 mmol/L NaCl. Phosphorus removal increased from 77 to 84% as the concentration of NaCl increased from 100 to 400 mmol/ L. 100 mmol/L concentration of NaCl showed a maximum microalgal biomass production and lipid productivity of 0.67± 0.03 and 0.185±0.03 g/L, respectively.