The biofouling process: The science behind a valuable phenomenon for aquaculture

Biofouling, the biological process leading to the accumulation of microorganisms, has been promoted for over a decade in aquaculture, particularly in biofloc technology, biofilm-based systems and recently aquamimicry. However, the science behind biofouling is largely unknown in aquaculture. This document brings the science behind the biofouling process, reviews and analyses available information about the different phases of such a unique natural process. In aquatic or high humidity environments, substrata rapidly become colonized by microbes. After molecules form a thin film on any surface, bacterial adhesions occur and bacteria–bacteria, bacteria–eukaryotes and bacteria–substrate interactions take place; bacterial adhesion entails the production of adhesins and polysaccharides production. Coaggregation continues after irreversible adhesion, but the activated genes during the adhesion process associated with flagella and pili are suppressed in this stage. Throughout the process, bacteria communicate by excreting signalling or self-inducing molecules, and other bacteria recognize these molecules that serve as a sort of checkpoint associated with their accumulation. Thereafter, the maturation phase is achieved and usually characterized by a colony equilibrium; some bacteria and other microorganisms achieve prominence in the colony, and many of the members have their functions and contributions to the microbial community. Finally, the detachment involves a complex but coordinated process involving several environmental signals, signal transduction pathways and effectors, promoting biofilm or biofloc split and dispersal to start the process again. In conclusion, biofouling is a complex, multifaceted process, but a deeper understanding of it and its consequent regulation would benefit microorganism-based aquaculture.