Biofilms in marine environments; implications for aquaculture, coral reefs, marine aquariums, and the human pathogen Vibrio cholerae – Part 1

INTRODUCTION
The lowly biofilm has generally been considered to have little significance to overall microbial pathogenesis. Basically a ball of mucus, it was believed to be simply an environmental survival strategy. However, recent study has shown biofilms to be a dynamic structure, allowing microbes to function nearly as a multicellular organism, even allowing for programmed cooperations between various species. It has only been recent years that microbial biofilms have been the subject of serious investigation, despite the importance of these structures in both pathogenesis and environmental survival. Previous study has focused on the study of microbes as unicellular individuals, rather that examining them as complex community organisms. An important advance in the study of biofilms arrived with the advent of confocal scanning laser microscopes (CSLM). Unlike scanning or transmission electron microscopy, which requires a dehydrated sample, CSLM’s allow the imaging of fully hydrated specimens. This instrument allows the visualization of the complex three-dimensional structures present in biofilms. Because the matrix assembling these structures consists primarily of exopolysaccharides, these structures are often lost in traditional electron microscopy.
Using confocal scanning laser microscopy, a generalized picture of biofilm structure has been produced. A biofilm consists of patchy aggregations of bacterial cells that are interspersed throughout a matrix of exopolysaccharides (EPS). This leads to tower-like structures with interspersed channels for the flow of water, nutrients and bodily fluids. These structures may be observed whether the biofilm is produced from a single species in laboratory culture, or is a complex mixture of species in natural biofilms.