The interactions of an algae–fungi symbiotic system influence nutrient removal from synthetic wastewater

Abstract BACKGROUND Algae–bacteria symbiotic system has attracted much attention in the fields of nutrients removal from wastewater. Fungi has also been demonstrated to promote the cultivation of microalgae. However, capability and mechanism of algae–fungi symbiotic system for nutrient removal remains unclear. RESULTS This study assessed the removal efficiencies of an algae–fungi symbiotic system of Chlorella variabilis NC64A and Ganoderma lucidum for chemical oxygen demand (COD cr ), total nitrogen (TN), total phosphorus (TP), and ammonia nitrogen (NH 3 ‐N) from synthetic wastewater. The highest levels of dry cell weight (DCW), chlorophyll‐a (Chl‐a), and enzyme activity in the algae–fungi symbiotic system were obtained at an algae–fungi mass ratio of 1:3. At this ratio, the system on the tenth day removed 75.5%, 76.7%, 74.7%, and 90.0% of COD cr , TN, TP, and NH 3 ‐N, respectively. Maximum values of both DCW (0.89 g L −1 ) and Chl‐a (2885 mg L −1 ) were achieved on day 6. Chlorella variabilis NC64A and G. lucidum coexisted as an algae–fungi consortium, in which G. lucidum exerted pressure on C. variabilis NC64A via enzymatic hydrolysis of cellulose in algal cell walls. CONCLUSION Algae–fungi interactions have the tendency to establish symbiosis and a fully autotrophic system without the need for an additional carbon source. © 2019 Society of Chemical Industry