Docosahexaenoic acid production of the marine microalga Isochrysis galbana cultivated on renewable substrates from food processing waste under CO2 enrichment

Abstract

Leftover dough is a starch-rich food processing waste of Chinese steamed bread. Leftover dough hydrolysates enriched with glucose and amino acids were used to cultivate the marine microalga Isochrysis galbana to produce docosahexaenoic acid (DHA) under CO2 enrichment. Isochrysis galbana could use mixed carbon sources (CO2, glucose, and amino acids) synchronously to grow and accumulate DHA. Cell growth, the uptake of glucose and amino acids, and DHA production were significantly affected by CO2 enrichment. The maximum biomass concentration of 3.85 g L−1 was achieved with 3 % CO2. And the maximum DHA yield was 65.5 mg L−1 d−1. To enhance DHA production, a two-stage cultivation strategy was successfully developed by this work. The maximum DHA yield of the two-stage culture was elevated by 2.3-fold. It is feasible to produce DHA by Isochrysis galbana using leftover dough under CO2 enrichment.