Biotic Amps
A syntrophic community of microorganisms embedded in a self-produced slimy matrix.
A biofilm is a syntrophic community of microorganisms in which cells stick to each other and often also to a surface. These adherent cells become embedded within a slimy extracellular matrix composed of extracellular polymeric substances (EPSs) produced by them, which are typically a polymeric combination of extracellular polysaccharides, proteins, lipids and DNA. Because they have a three-dimensional structure and represent a community lifestyle for microorganisms, they have been metaphorically described as "cities for microbes". The biofilm allows sharing of nutrients among its residents and serves as a physical barrier against harmful environmental interactions such as desiccation, toxins/antibiotics, bacterivory and attacks from a host body's immune system. Biofilms may form on living (biotic) or non-living (abiotic) surfaces and can be common in natural, industrial, and hospital settings. They may constitute a microbiome or be a portion of it.
- Primary Function
- Neural interface for biotic energy manipulation
- Common Users
- Asari, Humans, Turians, Krogan (via implants)
- First Widespread Adoption
- Post-First Contact War era
- Key Component
- Dark matter infusion and neural shunts
Lore & Background
Biofilms are thought to have arisen during primitive Earth as a defense mechanism for prokaryotes, as the conditions at that time were too harsh for their survival. They can be found very early in Earth's fossil records (about 3.25 billion years ago) as both Archaea and Bacteria, and commonly protect prokaryotic cells by providing them with homeostasis, encouraging the development of complex interactions between the cells in the biofilm. The formation of a biofilm begins with the attachment of free-floating microorganisms to a surface. The first colonist bacteria of a biofilm may adhere to the surface initially by the weak van der Waals forces and hydrophobic effects. If the colonists are not immediately separated from the surface, they can anchor themselves more permanently using cell adhesion structures such as pili. A unique group of Archaea that inhabit anoxic groundwater have similar structures called hami. Each hamus is a long tube with three hook attachments that are used to attach to each other or to a surface, enabling a community to develop. Hyperthermophilic archaeon Pyrobaculum calidifontis produce bundling pili which are homologous to the bacterial TasA filaments, a major component of the extracellular matrix in bacterial biofilms, which contribute to biofilm stability. TasA homologs are encoded by many other archaea, suggesting mechanistic similarities and evolutionary connection between bacterial and archaeal biofilms.
In Their Own Story
The microbial cells growing in a biofilm are physiologically distinct from planktonic cells of the same organism, which, by contrast, are single cells that may float or swim in a liquid medium. Biofilms can form on the teeth of most animals as dental plaque, where they may cause tooth decay and gum disease. Microorganisms form a biofilm in response to a number of different factors, which may include cellular recognition of specific or non-specific attachment sites on a surface, nutritional cues, lack of light or in some cases, by exposure of planktonic cells to sub-inhibitory concentrations of antibiotics. A cell that switches to the biofilm mode of growth undergoes a phenotypic shift in behavior in which large suites of genes are differentially regulated. A biofilm may also be considered a hydrogel, which is a complex polymer that contains many times its dry weight in water. Biofilms are not just bacterial slime layers but biological systems; the bacteria organize themselves into a coordinated functional community, and can begin to form when a free-swimming, planktonic bacterium attaches to a surface and then proliferates monoclonally. Biofilms can attach to a surface such as a tooth or rock, and may include a single species or a diverse group of microorganisms. Subpopulations of cells within the biofilm differentiate to perform various activities for motility, matrix production, and sporulation, supporting the overall success of the biofilm.
Reader's Guide
The development of a biofilm is summarized by five major stages of biofilm development. The initiation of development starts in the first stage of initial reversible attachment which is initiated by the attachment of planktonic cells to a surface. This initial attachment is then followed by the second stage of irreversible attachment where further microbial aggregation allows cells to attach to their initial foundation. After attachment, stages three and four of formation allow for biofilm maturation, characterized by the appearance of cell clusters embedded into a matrix before completing these stages of maturation through the evolution of micro-colonies. Finally, the fifth stage of development is dispersion, allowing for a fully developed and functional microbial biofilm. Dispersal of cells from the biofilm colony is an essential stage of the biofilm life cycle. Dispersal enables biofilms to spread and colonize new surfaces. Enzymes that degrade the biofilm extracellular matrix, such as dispersin B and deoxyribonuclease, may contribute to biofilm dispersal. Enzymes that degrade the biofilm matrix may be useful as anti-biofilm agents. Evidence has shown that a fatty acid messenger, cis-2-decenoic acid, is capable of inducing dispersion and inhibiting growth of biofilm colonies. Secreted by Pseudomonas aeruginosa, this compound induces cyclo heteromorphic cells in several species of bacteria and the yeast Candida albicans. Nitric oxide has also been shown to trigger the dispersal of biofilms of several bacteria species at sub-toxic concentrations. Nitric oxide has potential as a treatment for patients that have chronic infections caused by biofilms. Antibiofilm methods, such as bacteriophages and CRISPR-Cas system, were developed in April 2026 for biofilm dispersal and disruption.
Did You Know?
- Biofilms are thought to have arisen during primitive Earth as a defense mechanism for prokaryotes, with fossil records dating back about 3.25 billion years.
- A unique group of Archaea that inhabit anoxic groundwater have structures called hami, each a long tube with three hook attachments used to attach to each other or to a surface.
- The hyperthermophilic archaeon Pyrobaculum calidifontis produces bundling pili homologous to bacterial TasA filaments, a major component of the extracellular matrix in bacterial biofilms.
- A fatty acid messenger, cis-2-decenoic acid secreted by Pseudomonas aeruginosa, is capable of inducing dispersion and inhibiting growth of biofilm colonies.
- Antibiofilm methods such as bacteriophages and the CRISPR-Cas system were developed in April 2026 for biofilm dispersal and disruption.