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

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 K2HPO4 (Pi), sodium tripolyphosphate (STPP), glucose-6-phosphate (G-6-P), beta-sodium glycerophosphate (beta-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 beta-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.

Automated summary

The study found that Chlorella pyrenoidosa can utilize different forms of phosphorus to sustain its growth and affect the synthesis of biochemical components. In mixotrophic cultivation, phosphorus is mainly stored in intracellular phosphorus pools, while in photoautotrophic cultivation, excess phosphorus is quickly absorbed and released. G-6-P enhances AKP activity and promotes organic phosphorus hydrolysis.