Fig 1.
Schematic diagram of the novel DHA production process using by-products for microalgal fermentation.
The rapeseed meal hydrolysate was obtained through the treatment of solid state fermentation followed by fungal autolysis. It was used as organic nitrogen source, and the hydrolyzed waste molasses was used as organic carbon source.
Fig 2.
Congo red staining of fungal strains with cellulolytic activity.
The fungal strains were grown on agar plate containing 1% (wt/vol) sodium carboxymethyl cellulose (CMC-Na) and 1.4% (wt/vol) agar. CMC hydrolysis was detected by the Congo red staining after being incubated for 3 d.
Fig 3.
Total nitrogen and sugar contents of the meal hydrolysates.
RMHs were obtained by fungal solid state fermentation (pre-treatment) followed by autolysis. Three fungal strains were used for solid state fermentation and autolysis individually. Data are means of three replicates, and error bars show standard deviations.
Fig 4.
The contents of free amino nitrogen and inorganic phosphorus in N. crassa derived hydrolysate.
The rapeseed meal was fermented with N. crassa J2 at 30°C and sampled at various time points for analytical experiments; Data are means and standard deviations from triplicate fermentations.
Fig 5.
Biomass concentration of C. cohnii grown on RMH supplemented with yeast extract.
The meal hydrolysates produced by individual fungal stains were supplemented with different levels of yeast extract. Data of biomass concentration are means of three replicates, and error bars show standard deviation.
Table 1.
Effect of supplemented yeast extract on lipid production by C. cohnii on individual RMH medium.
Fig 6.
Biomass concentration of C. cohnii grown on individual RMH supplemented with waste molasses.
The meal hydrolysates produced by individual fungal stains were supplemented with different levels of molasses. Data of biomass concentration are means of three replicates, and error bars show standard deviation.
Table 2.
Effect of supplemented waste molasses on lipid production by C. cohnii on individual RMH medium.
Fig 7.
Transmission electron micrograph of C. cohnii cells.
Microalga cells were grown on seawater based GYE containing glucose and yeast extract (A, B) or RMH-molasses medium composed of the meal hydrolysate and waste molasses (C, D) for 7 days.
Fig 8.
Biomass and lipid production by C. cohnii grown on RMH supplemented with different carbon sources.
(A) Effect of supplemented carbon sources on biomass concentration and DHA yield of C. cohnii grown on basal meal hydrolysate. Data are means of three replicates, and error bars show standard deviation; (B) Fatty acid composition of C. cohnii grown on the Penicillium sp.-produced RMH supplemented with different carbon sources.