Biofilm: Introduction, Composition, Application, and Keynotes

Introduction

Biofilm refers to a complex community of microorganisms, such as bacteria, fungi, or algae, that adhere to surfaces and are encased within a self-produced matrix of extracellular polymeric substances (EPS). These microorganisms form a structured, organized, and protective community within the biofilm.

Key points about it include:

  1. Formation: They are formed through a series of steps. Initially, planktonic microorganisms attach to a surface, after which they start to multiply and produce EPS, creating a protective matrix. This matrix helps in the adhesion of additional microorganisms, leading to the growth and maturation of the it.
  2. Composition: They consist of microorganisms embedded in the EPS, which is primarily composed of polysaccharides, proteins, nucleic acids, and lipids. The composition of EPS varies depending on the microorganisms and environmental conditions.
  3. Structure: Biofilms exhibit a complex three-dimensional structure with channels and voids that allow for the exchange of nutrients, waste products, and signaling molecules. This structure provides protection to the microorganisms within the biofilm, making them more resistant to antimicrobial agents and immune responses.
  4. Persistence and Adaptability: They are highly persistent and can colonize various surfaces, including medical devices, pipes, teeth, and natural environments like rocks and water surfaces. Microorganisms within biofilms can adapt to changing conditions and exhibit increased resistance to antibiotics and host defenses.
  5. Role in Infections: They play a significant role in many chronic and recurrent infections. They can form on tissues, implants, or medical devices, leading to infections that are difficult to treat. Biofilms provide a protected environment for microorganisms, making them more resistant to antimicrobial agents and immune clearance.
  6. Impact on Industries: Theycan cause biofouling and corrosion in industrial settings, leading to reduced efficiency and increased maintenance costs. They can form in water systems, pipelines, food processing equipment, and other industrial surfaces.
  7. Study and Control: Understanding biofilm formation, structure, and interactions is important for developing strategies to control and manage biofilm-related issues. Research focuses on developing antimicrobial agents, surface modifications, and biofilm-disrupting techniques to prevent or remove them.

Composition


The composition of biofilm can vary depending on the type of microorganisms involved, the environment in which the biofilm forms, and the stage of its development. However, the general composition of it includes the following components:

Biofilm- Introduction, Composition, Application, and Keynotes
Fig. Biofilm of Klebsiella pneumoniae
  1. Microorganisms: They are comprised of various microorganisms, such as bacteria, fungi, algae, or a combination of these. The specific species and their relative abundance can vary, but multiple species often coexist within a biofilm.
  2. Extracellular Polymeric Substances (EPS): EPS is a key component of biofilm structure and function. It is produced by the microorganisms within it and forms a matrix that surrounds and protects the microbial cells. EPS is primarily composed of:
    • Polysaccharides: These include various sugars, such as glucose, mannose, and fructose. Polysaccharides provide structural integrity to the biofilm and play a role in adhesion to surfaces.
    • Proteins: Biofilm-associated proteins (Bap) and other proteins are present in the EPS matrix. They contribute to its stability, adhesion, and interactions with the environment.
    • Nucleic Acids: Extracellular DNA (eDNA) is a significant component of EPS. It can be released by the microorganisms within the biofilm or derived from lysed cells. eDNA helps in biofilm structure, stability, and gene transfer.
    • Lipids: Lipids, including fatty acids and lipopolysaccharides, can be found in the EPS matrix. They contribute to biofilm stability and protection.
  3. Water Channels: Biofilms contain a network of water channels that facilitate the transport of nutrients, waste products, and signaling molecules within the biofilm. These channels also allow for gas exchange and support the metabolic activity of the microorganisms.
  4. Inorganic Materials: In some cases, biofilms may incorporate inorganic materials from the environment or host surfaces. For example, biofilms in dental plaque can mineralize and incorporate calcium and phosphate ions, leading to the formation of dental calculus or tartar.

It’s important to note that the composition of biofilms can be heterogeneous, with variations in the distribution and organization of different components throughout the biofilm structure. Additionally, the composition can change dynamically as the biofilm develops and interacts with its environment.

Application


Biofilms have diverse applications across various fields due to their unique properties and complex structure. Here are some notable applications of them:

  1. Wastewater Treatment: They play a vital role in wastewater treatment processes. They are used in biofilm reactors, such as trickling filters and rotating biological contactors, to break down organic matter and remove pollutants. Biofilms enhance the efficiency of wastewater treatment by providing a large surface area for microbial attachment and enabling the degradation of contaminants.
  2. Bioremediation: They are employed in bioremediation processes to clean up contaminated environments. Microorganisms within biofilms can degrade or transform pollutants, such as hydrocarbons, heavy metals, and pesticides, making them useful for the restoration of polluted soil, water, and air.
  3. Biocorrosion Control: They formed on metal surfaces can lead to corrosion. However, understanding and controlling biofilm formation can help mitigate biocorrosion issues. By studying the interactions between biofilms and metal surfaces, strategies can be developed to prevent or manage corrosion in industrial settings, such as pipelines, ships, and oil rigs.
  4. Medical Device Coatings: Its formation on medical devices, such as catheters and implants, can lead to infections and complications. Researchers are exploring the use of biofilm-resistant coatings for medical devices to prevent biofilm attachment and colonization. These coatings may incorporate antimicrobial agents or surface modifications to discourage biofilm formation.
  5. Agriculture and Crop Protection: They can be used in agriculture for various purposes. For example, biofilm-forming bacteria can be applied to plant surfaces to enhance nutrient uptake and improve plant health. Additionally, biofilms can be harnessed for the biocontrol of plant diseases by introducing beneficial microorganisms that form biofilms and compete with or antagonize pathogens.
  6. Biotechnology and Bioprocessing: They have applications in biotechnological processes, such as wastewater treatment, biofuel production, and bioreactor systems. Biofilm reactors provide a favorable environment for the growth of microorganisms and can enhance productivity and efficiency in bioprocessing.
  7. Sensor Development: They can be used as a sensing element in biosensors. They can be engineered to respond to specific molecules or environmental conditions, enabling the detection and monitoring of analytes or changes in their surroundings. Biofilm-based sensors have potential applications in environmental monitoring, healthcare diagnostics, and food safety.
  8. Food Industry: They can form on food processing equipment and surfaces, leading to contamination and spoilage. Understanding biofilm formation and control strategies is crucial for maintaining food safety and preventing biofilm-related issues in food processing facilities.

Keynotes

Here are some keynotes on biofilms:

  1. Biofilms are complex communities of microorganisms that adhere to surfaces and are encased within a self-produced matrix of extracellular polymeric substances (EPS).
  2. They can be formed by bacteria, fungi, algae, or a combination of these microorganisms.
  3. The EPS matrix provides structural integrity to the biofilm and protects the microbial cells from external stresses, such as antimicrobial agents and immune responses.
  4. They have a three-dimensional structure with water channels that allow for nutrient and waste exchange, as well as communication among the microorganisms.
  5. They can form on various surfaces, including natural and artificial environments, such as rocks, pipes, medical devices, and teeth.
  6. They play a role in several beneficial and harmful processes. They contribute to wastewater treatment, bioremediation, nutrient cycling, and symbiotic interactions. However, they can also cause biofouling, biocorrosion, and chronic infections.
  7. They exhibit enhanced resistance to antimicrobial agents compared to their planktonic counterparts. This resistance is attributed to the protective matrix, reduced penetration of antimicrobials, altered microbial physiology, and gene expression.
  8. Biofilm-related infections can be challenging to treat and often require targeted strategies to disrupt or remove the biofilm, along with appropriate antimicrobial therapy.
  9. Understanding the formation, structure, and interactions within biofilms is crucial for developing strategies to control and manage biofilm-related problems.
  10. Research on biofilms focuses on various aspects, including biofilm formation mechanisms, quorum sensing, biofilm dispersal, biofilm engineering, and biofilm-based technologies.
  11. They have applications in wastewater treatment, bioremediation, medical device coatings, agriculture, biotechnology, sensor development, and the food industry.
  12. Developing strategies to prevent or control biofilms involves studying biofilm formation processes, identifying biofilm-specific targets, and exploring antimicrobial and biofilm-disrupting agents.
  13. The study of them is an interdisciplinary field, involving microbiology, biochemistry, engineering, ecology, and medical sciences.
  14. Ongoing research in biofilm science aims to uncover new insights into biofilm formation, function, and control, with the goal of improving human health, environmental sustainability, and industrial processes.

Further Readings

  1. Flemming, H.-C., Wingender, J., & Szewzyk, U. (2016). Biofilms: An emergent form of bacterial life. Nature Reviews Microbiology, 14(9), 563-575. doi: 10.1038/nrmicro.2016.94
  2. Donlan, R. M. (2002). Biofilms: Microbial life on surfaces. Emerging Infectious Diseases, 8(9), 881-890. doi: 10.3201/eid0809.020063
  3. Hall-Stoodley, L., Costerton, J. W., & Stoodley, P. (2004). Bacterial biofilms: From the natural environment to infectious diseases. Nature Reviews Microbiology, 2(2), 95-108. doi: 10.1038/nrmicro821
  4. Flemming, H.-C., & Wingender, J. (2010). The biofilm matrix. Nature Reviews Microbiology, 8(9), 623-633. doi: 10.1038/nrmicro2415
  5. Stewart, P. S., & Costerton, J. W. (2001). Antibiotic resistance of bacteria in biofilms. The Lancet, 358(9276), 135-138. doi: 10.1016/S0140-6736(01)05321-1
  6. Parsek, M. R., & Singh, P. K. (2003). Bacterial biofilms: An emerging link to disease pathogenesis. Annual Review of Microbiology, 57, 677-701. doi: 10.1146/annurev.micro.57.030502.090720
  7. Høiby, N., Bjarnsholt, T., Givskov, M., Molin, S., & Ciofu, O. (2010). Antibiotic resistance of bacterial biofilms. International Journal of Antimicrobial Agents, 35(4), 322-332. doi: 10.1016/j.ijantimicag.2009.12.011
  8. Sutherland, I. W. (2001). The biofilm matrix—an immobilized but dynamic microbial environment. Trends in Microbiology, 9(5), 222-227. doi: 10.1016/S0966-842X(01)02012-1
  9. Ciofu, O., Rojo-Molinero, E., & Macia, M. D. (2017). Oliver A. Antibiotic treatment of biofilm infections. APMIS, 125(4), 304-319. doi: 10.1111/apm.12699
  10. Flemming, H.-C., & Wuertz, S. (2019). Bacteria and archaea on Earth and their abundance in biofilms. Nature Reviews Microbiology, 17(4), 247-260. doi: 10.1038/s41579-019-0158-9

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