Multidimensional interaction mechanisms and engineering applications of microalgae-fungal microorganism symbiotic systems.

The symbiotic system of microalgae and fungal microorganisms, such as filamentous fungi, yeasts, and lichen-forming fungi, holds great potential in the fields of environmental remediation and bioresource development. Yet, it faces bottlenecks, including unclear symbiotic mechanisms, high energy consumption for biomass harvesting, poor adaptability to complex wastewater, and insufficient system integration. In this review, we systematically summarized the research progress on microalgae-fungi symbiotic systems in terms of germplasm resource exploration, multifaceted interaction mechanisms, and engineering applications. In particular, we focused on the core advantages of fungal pellet-assisted bioflocculation technology in overcoming the energy bottleneck of biomass harvesting, as well as its optimization strategies. The comprehensive performance of this system in wastewater purification, bioenergy accumulation, and high-value metabolite production was also evaluated. By integrating fundamental mechanisms with engineering application outcomes, we aimed to provide theoretical support and technical guidance for the construction of efficient, stable, and sustainable microalgae-fungi biorefinery platforms. Furthermore, we seek to facilitate the translation of this technology from laboratory research to industrial application.