Fungal pellets as biotechnological tools for addressing environmental and industrial challenges: a comprehensive...

Pellets are ultrastructural configurations of filamentous fungal biomass that form during growth in submerged culture. This growth pattern offers advantages for controlling and stabilizing bioprocesses through biomass immobilization, reduced medium viscosity, and facilitated compound extraction. These benefits are particularly valuable for bioremediation, synergistic applications with biomaterials, and industrial metabolite production. However, fungal pellets also present challenges, such as limited oxygen diffusion to the pellet core, inconsistent pellet homogeneity, and decreased productivity. Factors such as electrostatic interactions, hydrophobicity, and culture conditions influence pellet formation. Currently, optimization efforts for pellet production focus on evaluating parameters, such as: pH range, agitation rate, pellet formation time, carbon source, additive agents, trace metals, and inoculum concentration, among others. Fungal pellets are increasingly recognized as promising platforms in emerging environmental biotechnology due to their versatility in pollutant removal and sustainable processing. Unlike previous reviews, this work provides an integrated and up-to-date perspective that combines the fundamentals of pellet formation with recent advances in their environmental and industrial applications, highlighting strategies for optimization and scalability. This review focuses on analyzing the most relevant aspects of fungal pellets, including their formation, optimization, and biotechnological applications. Given the growing importance of fungi in contemporary biotechnology, a state-of-the-art review of fungal pellets is warranted. This includes presenting an updated overview of processes for generating fungal biomass with enhanced handling, based on the use of fungal granules, an essential component for the implementation of efficient biotechnological processes using model fungal pellets with relevant industrial applications.