The marine microalga Chlorella stigmatophora as a potential source of single cell protein: Enhancement of the protein content in response to nutrient enrichment

Abstract

Mass cultures of Chlorella stigmatophora were carried out in order to obtain maximum protein production and to study the chemical variations in function of the nutrient concentration. Cultures reached maximum cellular densities of 2.2·108 cells/ml, with a growth velocity between 0.49 and 0.55 doublings/day. Carbohydrate content in the stationary phase ranged between 2.23 and 2.74 pg/cell, RNA between 0.78 and 1.36 pg/cell and DNA between 0.013 and 0.016 pg/cell. The maximum value for chlorophyll a was 0.13 pg/cell. Maximum protein content was obtained with a nutrient concentration of 16 mM of NaNO3, giving 4.85 pg/cell and a protein concentration of 0.7 g/l. The protein content can be manipulated by changes in the nutrient concentration, showing differences up to a 9.2-fold increase. This characteristic makes Chlorella stigmatophora a suitable source of single cell protein.