Autoinducers are molecules that are small enough to diffuse through cell membranes, that initiate gene activation for functions necessary for cell populations that have reached a critical density. 

Autoinducers

1) Binding of the Autoinducer 
2) Gene Expression
3) Increase in Signaling Molecule Production 

Steps of Quorum Sensing

Signaling molecules exist in two categories: Gram-negative bacteria utilizing N-acylated homoserine lactones, or Gram-positive utilizing mostly small peptides. 

Signaling Molecules

Quorum sensing is how different cell species in biofilms can communicate with one another, specifically about cell density. This is an essential response to environmental stimuli facilitated by autoinducers. 

Biofilms are complex populations composed of many different types of microorganisms in a structured ecosystem. Biofilms provide the microbes with an advantageous growth circumstances where the waste product from one organism may be the nutrients for another. They can be found in various environments stuck to surfaces.

Biofilms

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Microbiology covers the scope and sequence requirements for a single-semester microbiology course for non-majors. The book presents the core concepts of microbiology with a focus on applications for careers in allied health. The pedagogical features of the text make the material interesting and accessible while maintaining the career-application focus and scientific rigor inherent in the subject matter. Microbiology’s art program enhances students’ understanding of concepts through clear and effective illustrations, diagrams, and photographs.

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The structure of biofilms are dependent on the environment in which they exist and nutrient availability. The collection of microorganisms within a biofilm are all embedded in an extracellular matrix with water channels. 

Structure of Biofilms

Quorum Sensing

Biofilms are prevalent inside of human bodies and on many of the devices we use. While few biofilms are helpful for example in our intestinal and respiratory tracts, many can be harmful to our health.

Applications of Biofilms to Human Health

Biofilm formation occurs in five stages:
1) Attachment of Planktonic Cells 
2) Colonizer Attachment
3) Microbial Growth
4) EPS Production and Formation
5) Secondary Colonizer Attachment and Microbial Dispersion

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