The effects of salinity on the growth and biochemical properties of Chlamydomonas mexicana GU732420 cultivated in municipal wastewater

Abstract

A freshwater microalga Chlamydomonas mexicana was grown on municipal wastewater with different levels of salinity up to 400 mmol/L NaCl, and the biochemical properties were characterized after 10 days of cultivation. C. mexicana showed the higher specific growth rates for 100 and 200 mmol/L NaCl. Nitrogen was completely removed within 10 days as a result of algal growth promoted by the addition of 200–400 mmol/L NaCl. Phosphorus removal increased from 77–84% as the concentration of NaCl increased from 100 to 400 mmol/L. The highest removal of total inorganic carbon (66%) was obtained with the addition of 200 mmol/L NaCl. The lipid content increased from 17% to 38% as the concentration of NaCl increased from 0 to 400 mmol/L. The total fatty acid content and glycerol yield of C. mexicana increased 1.8- and 4-fold in wastewater amended with NaCl, respectively. Fatty acids accumulated in the algal biomass were mainly composed of palmitic (27–29%), γ-linolenic (27–30%), and linolelaidic acids (16–18%). The optimal condition for fatty acids production in C. mexicana was observed when the municipal wastewater was amended with 100–200 mmol/L NaCl with a simultaneous removal of nutrients.