Synergism and Mutualistic Symbiosis Mechanism between Microalgae and Fungi in Fungi-Microalgae Symbiotic System

The interaction mechanism in the FMSS was explored using Aspergillus fumigatus and Synechocystis sp. PCC6803. SEM and TEM showed that microalgae can be fixed on the surface of fungal mycelium pellets because of the bridging effect of EPS on the surface of the fungal mycelium. Microalgae had good activity during the symbiotic process. Zeta analysis showed that there was electrostatic attraction between positive and negative charges during symbiosis between fungi and microalgae. FTIR and XPS results showed that amino, amide, phosphate, hydroxyl, and aldehyde groups played important roles in the symbiotic system. The N cycling and CO2-O2 cycling promoted the synthesis of amino acids and provided a guarantee for gas exchange in the FMSS, and the intermediate metabolites (CO32- and HCO3- /H2CO3 ) satisfied the metabolic activities of microalgae and fungi. The microalgae and fungi worked in coordination each other, which was the mutualistic symbiosis.