Cultivation of Chlorella pyrenoidosa with different phosphorus forms under photoautotrophic and mixotrophic modes: Biochemical component synthesis and phosphorus bioavailability appraisement

Abstract

Microalgae cultivation with wastewater could reduce the water pollution and relieve global energy crisis. Nowadays, there is few study on the bioavailability of phosphorus forms in wastewater for microalgae growth and biochemical component synthesis. In this study, Chlorella pyrenoidosa was cultivated under photoautotrophic and mixotrophic modes with five phosphorus forms, including K 2 HPO 4 (Pi), sodium tripolyphosphate (STPP), glucose-6-phosphate (G-6-P), β-sodium glycerophosphate (β-glycerol-P), and adenosine triphosphate (ATP). Results showed that Chlorella pyrenoidosa could utilize all phosphorus forms to sustain its growth. Pi was the preferred phosphorus form that could be absorbed directly, while monophosphates (G-6-P and β-glycerol-P) could promote the accumulation of carbohydrate, protein and chlorophyll- a . Regarding phosphorus absorption and utilization, most of phosphorus in mixotrophic bulk were transformed and stored in intracellular phosphorus pool, whereas photoautotrophic microalgae absorbed excess phosphorus in a short time and released subsequently. The G-6-P enhanced the AKP activity and improved organic phosphorus hydrolysis. Results will provide valuable information for mixotrophic microalgae cultivation with different phosphorus forms, and further for phosphorus recovery and high density microalgae cultivation in wastewater. • Effect of phosphorus forms on microalgae growth and intracellular component. • Different bioavailability and utilization strategy of phosphorus forms. • Mixotrophy improved the performance of phosphorus absorption and utilization. • G-6-P was more effective for protein and carbohydrate accumulation.