Exam 4: A Survey of Prokaryotic Cells and Microorganisms

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Biofilms are complex communities of microorganisms, primarily bacteria, that adhere to surfaces and are embedded in a self-produced extracellular matrix of polymeric substances. They are formed through a process called biofilm formation, which involves the initial attachment of bacteria to a surface, followed by the production of extracellular polymeric substances that help to anchor the bacteria and protect them from environmental stresses.

One of the unique properties of biofilms is their resistance to antimicrobial agents and the immune system. This is due to the protective nature of the extracellular matrix, which acts as a physical barrier and also helps to sequester nutrients and signaling molecules. Additionally, the close proximity of bacteria within the biofilm allows for the exchange of genetic material, leading to increased genetic diversity and the potential for the development of antibiotic resistance.

In the environment, biofilms play a significant role in various processes such as nutrient cycling, bioremediation, and the degradation of organic matter. They also contribute to the formation of dental plaque, which can lead to oral diseases such as cavities and gum disease. In the human body, biofilms are associated with chronic infections, such as those related to medical devices like catheters and implants, as well as chronic wounds and cystic fibrosis.

A biofilm differs from a typical bacterial colony growing on a nutrient agar medium in several ways. While both involve the growth of bacteria, a biofilm is a more complex and structured community, whereas a bacterial colony on agar is a simple aggregation of cells. Additionally, the extracellular matrix present in biofilms is absent in bacterial colonies on agar, making biofilms more resistant to environmental stresses and antimicrobial agents. Furthermore, the close proximity of bacteria within a biofilm allows for the exchange of genetic material, leading to increased genetic diversity and the potential for the development of antibiotic resistance, which is not typically seen in bacterial colonies on agar.