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BACKGROUND In recent years, mixotrophic culture of algal cells has been gaining increasing interest, largely because it offers an efficient means of commercial production of lipids and other value‐added products. In this work, the impacts of glucose addition on the biomass production, chemical composition and fatty acid profiles of Chlorella kessleri were investigated to exploit the relationships between extra organic carbon and changes in the distribution of chemical compositions in algal cells. RESULTS Results showed that C. kessleri grew fast in the mixotrophic cultures with a maximum algal biomass and specific growth rate of 4.46 g L−1 and 1.27 day−1, respectively. Glucose in the cultures was absorbed and utilized effectively by this alga, whose uptake efficiencies ranged from 88.2% to 98.3%, but it had a negative impact on the synthesis of photosynthetic pigments. Additionally, the culture's pH and chemical composition, including pigments, carbohydrate, protein and lipids, in this alga varied with the change of glucose concentrations in the cultures. The fatty acid profiles of this alga indicated that its biomass could be used as live feeds in aquaculture or a good‐quality feedstock for biodiesel production. CONCLUSIONS These results suggested that adding an extra organic carbon source (glucose) to a photoautotrophic culture was a potentially effective way to improve the performance in mixotrophically culture of microalgae, for example in terms of higher biomass and lipid production. © 2018 Society of Chemical Industry

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BACKGROUND: Previous studies have documented that searching for wastewaters with appropriate nutrient profiles to cultivate microalgae directly was an effective measure to reduce the cost of algae cultivation. In this work, wastewaters collected from different processing units of the silk industry were used to cultivate Chlorella sorokiniana directly or after preliminary pretreatment for producing algal biomass and removing nutrients. RESULTS:The data showed that C. sorokiniana could grow on reeling wastewater and cooking cocoon wastewater with a maximum biomass of 0.26 and 0.49 g L −1 , respectively, but could not grow on frigon wastewater because of high salinity and turbidity. Furthermore, the binary mixed wastewaters were used to cultivate this alga, which were mixed according to the algal nutritional requirements. Results indicated that the highest algal biomass (0.56 g L −1 ), and total nitrogen and phosphorus removal efficiencies (71.7% and 97.1%) were obtained when frigon wastewater was diluted with reeling wastewater (v/v) at a dilution multiple of eight, which was used as the algal culture media. Additionally, contents of protein, lipids, carbohydrates, and pigments in the algal cells varied with the changes in nutrient profiles of wastewaters. CONCLUSIONS: It is concluded that (i) reeling wastewater and cooking cocoon wastewater were rich in nutrients for the growth of C. sorokiniana, which could be used as algal culture medium directly; and (ii) growing C. sorokiniana on mixed wastewaters could enhance biomass production and nutrient removal. Thus, the silk industry wastewaters could be considered as suitable media to cultivate microalgae directly or by simply mixing. Figure 4. Variations in the concentrations of nutrients and the culture's pH when Chlorella sorokiniana grew on the mixed silk industry wastewater (SIW) for 7 days. (a) Total nitorgen (TN) removal; (b) total phosphorus (TP) removal; (c) chemical oxygen demand (COD) removal; and (d) pH variation. Each point represents the mean of three replicates, and the error bars represent the standard deviation.wileyonlinelibrary.com/jctb