Imaging the Microprocesses in Biofilm Matrices

Biofilms, which are aggregates of microorganisms and extracellular matrices, widely colonize natural water bodies, wastewater treatment systems, and body tissues, and have vital roles in water purification, biofouling, and infectious diseases. Recently, multiple imaging modalities have been developed to visualize the morphological structure and material distribution within biofilms and to probe the microprocesses in biofilm matrices, including biofilm formation, transfer and metabolism of substrates, and cell–cell communication. These technologies have improved our understanding of biofilm control and the fates of substrates in biofilms. In this review, we describe the principles of various imaging techniques and discuss the advantages and limitations of each approach to characterizing microprocesses in biofilm matrices. Various imaging techniques have been developed for visualizing microprocesses in biofilm matrices. Imaging the biofilm formation-related cell adhesion events, signal-sensing molecules, metabolites, and physiological states can help to control and utilize biofilms. The binding and transformation mechanisms of environmental pollutants within biofilms can be elucidated in depth by mapping the distributions of pollutants and their metabolites within biofilm matrices. Combinations of multiple analytical techniques, and reduced effects of labels on biofilm functions, are needed for more comprehensive and precise analysis of biofilm microprocesses.