Chapter 9: Biofilms

Approximately __% of microorganisms live in biofilms, as long as there is at least a minimal amount of _______ and _______

Approximately 95% of microorganisms live in biofilms, as long as there is at least a minimal amount of water and nutrients

What are some surfaces that biofilms can grow on?

biodiesal tanks human body rocks Biofilms form on a wide variety of surfaces, including living tissues, indwelling medical devices, natural, and industrial systems

Enzyme retention

biofilm benefit external digestion system cells put a lot of energy into making enzymes. This matrix makes a shell for bacteria to trap enzymes in place. Reduce the number of enzymes they need to produce works with quorum sensing with autoinducers getting stuck

Void

can be full of water or waste products if all nutrients are absorbed on the outside, nothing gets to this middle anyway

the architecture of a biofilm

channels and grooves in biofilm increase surface area to volume ratio to allow more nutrients to diffuse (like lungs) Support the transport of nutrients (C) Biofilm after injection of an aqueous solution containing a mixture of fluorescent beads reveals the connectivity of the channels. (D) SEM image of a wrinkle cross-section. (E) SEM image of the underside of a biofilm

competition

continuous regeneration

Planktonic bacteria

free flowing bacterial cells that are suspended

Biofilms provide

habitat diversity/localized gradient facilitate resource captures promote community interconnectivity protect cells from environmental hazards sorption Enzyme retention Cooperation competition Tolerance and resistance

Infections among hospitalized patients are often related to the presence of a medical device in the patient. Which conditions favor the formation of biofilms on in-dwelling catheters and prostheses?

in-dwelling catheters because it is warm, nutrient rich environment with good flow -Cells in the deep layers of a biofilm are metabolically inactive and may be less susceptible to the action of antibiotics that disrupt metabolic activities.-Phenotypic changes may also contribute to the increased resistance exhibited by bacterial cells in biofilms.- biofilms provide an ideal environment for the exchange of extrachromosomal DNA, which often includes genes that confer antibiotic resistance.

What are the Benefits of Biofilms to microbes?

like an incubator/habitat for microbes that allow them to thrive -support, nutrients, habitate diversity, and protect cells from environmental hazards

Streamer

loosely connected mucus streamer that hangs off the end of the biofilm that has a lot of surface area and has access to a lot of nutrients

persister cells

microbes with genetic characteristics allowing for their survival when exposed to an antibiotic kinda dormant but can come back into action any time

Opsonization

process of an antibody binding to an antigen one of the way our body helps fight off infection

localized gradient

provided by biofilm Some bacteria prefer nutrient rich environments. Some bacteria use the waste products of the these bacteria the gradient allows these different bacteria to find their preferred environment in the gradient Little habitats to fit the organisms niche

cooperation

synergistic micro-consortia quorum sensing-virulence factors or genes

Tolerance and resistance

the biofilm as a fortress antibiotics and chemical disinfectants

channel

underneath or above the colony allowing water to flow through allowing nutrients to diffuse faster via increased surface area to volume ratio

microcolonies

(clusters of up to 50 cells)

Many variables are important to cell attachment, biofilm formation, and development

-temperature: must be at a temp that microorganisms like -Adhesion to surface: texture or roughness, hydophobicity, surface chemistry, charge, conditioning film Bulk fluid: flow velocity, pH, temperature, cations, presence of antimicrobial products, nutrient availability Cell: cells surface hydrophobicity, extracellular appendages, extracellular polymeric substances, signalling molecules example: painted stainless steel affected biofilm formation. Added VC-18 with copper or TBTF or alone. VC-18 helps slow biofilm formation

features of biofilm

-tends to be negatively charged b/c the high concentration of cells inside and proteins embedded are often negatively charged too -oxygen and nutrients flow in --some bacteria form toward the outside to get as much oxygen as possible. They produce waste which goes toward the middle FAST --aerotolerant or obligate anerobic form in the middle where there is little to no oxygen and few nutrients. Use waste from outer growing SLOW -Genetic diversity: cell lyses but genetic material is consumed or absorbed -Quorum sensing -persister cells: kinda dormant but not like spores

How does a biofilm form? biofilm formation

1. Organic and inorganic molecules and ions pre-condition the surface making conditioning layer. Molecules and ions may also be used as: nutrients, electron acceptors, electron cofactors, and trace elements 2. Planktonic cells reversibly adhere to the surface reversibly 3. After a critical residence time, cells irreversibly attach to the surface 4. Irreversibly attached cells begin to replicate and produce substantial EPM --- Quorum sensing is the production of chemical signal molecules that increase in concentration as cell density increase 5. Secondary colonizers attach and water channels form between adjacent microcolonies 6. External parts of the biofilm may detac

. Order the following stages of the development of a biofilm from the earliest to the last step. 1. secretion of EPS 2. reversible attachment 3. dispersal 4. formation of water channels 5. irreversible attachment

2. reversible attachment 5. irreversible attachment 1. secretion of EPS 4. formation of water channels 3. dispersal

biofilms

A biofilm is a community of microbial cells that are attached to a surface by an extracellular polymeric matrix (EPM)

Planktonic cells reversibly adhere to the surface reversible attachment

Bacteria approach a surface using flagella Initial attachment is held by van der Waals interactions Tighter contact through pili or fimbriae Attachment is still reversible at this point adsorption

Biofilms and wastewater

Bacteria growing in biofilms help remove dissolved organics from wastewater take water and spray over bed rock with biofilm. Water trickles through and bacteria take some of the harmful stuff off.

biofilms and industrial systems

Biofilms can cause industrial systems to fail example: took metal coupons into the biofuel storage tanks. Biofilms can cause localized corrosion in fuel storage tanks. Work same as plaque

Where can biofilms form?

Biofilms form on a wide variety of surfaces, including living tissues, indwelling medical devices, natural, and industrial systems Biofilm growing on streambed rocks in High Ore Creek, MT Biofilms can create daily variations in dissolved nutrients in stream waters

Where do biofilms form?

Biofilms form on a wide variety of surfaces, including living tissues, indwelling medical devices, natural, and industrial systems example: dental plaque> 600 different species of bacteria have been detected in dental plaque, the majority of which are unculturable -inside use anereobic fementation that produce acids that degrade teeth example: Catheter Methicillin-resistant Staphylococcus aureus biofilm growing on a catheter The NIH estimates that 80% of infections are caused by microorganisms growing in a biofilm

biofilms and the immune system

Biofilms protect pathogens from the immune response -opsonization: can't bind to cell -Leukocyte phagocytosis: trying to eat a McDonalds building vs a hamburger If immune response starts being very active, the bacteria can leave biofilm and migrate to other areas of the body causing bacteremia or sepsis

Which is a reason for antimicrobial resistance being higher in a biofilm than in free-floating bacterial cells? A. The EPS allows faster diffusion of chemicals in the biofilm. B. Cells are more metabolically active at the base of a biofilm. C. Cells are metabolically inactive at the base of a biofilm. D. The structure of a biofilm favors the survival of antibiotic resistant cells.

C. Cells are metabolically inactive at the base of a biofilm.

Cells growing in a biofilm are ___________x more resistant to antibiotics than planktonic cells. Why?

Cells growing in a biofilm are 100-1000x more resistant to antibiotics than planktonic cells -Physical barrier -Charged matrix (positive charge is repelled an negative can be deactivated) -Horizontal gene transfer (antibiotic resistance kicked out and are there for all cells to be picked up) -Degradation of antibiotics (extracellular enzymes can neutralize antibiotics and can shield those who don't produce them) -Persister cells (chilling and antibiotic kinda need them to be active) -Diversity (a lot of bacteria won't grow in pure cultures in the lab)

What are the types of architecture in a biofilm

Channel Void Streamer Bulk fluid Cell cluster

Extracellular polymeric matrix

EPM 97% water attach biofilm to a surface has polysaccharides, protiens etc to make it viscous and sticky

After a critical residence time, cells irreversibly attach to the surface irreversible attachement

Extended surface contact triggers the production/secretion of adhesive extracellular polymeric matrix (EPM) Matrix consists of proteins (1-2%), polysaccharides (1-2%), nucleic acids (< 1%) and water (~97%) Binding is irreversible at this point only in that it would have to invest a lot of energy to get away

Predict how abiotic variables affect biofilm formation

Many variables are important to cell attachment, biofilm formation, and development

conditioning layer

Organic and inorganic molecules and ions pre-condition the surface allows planktonic cells to initially stick. These molecules and ions may also be used as: nutrients electron acceptors enzymatic cofactors trace elements Change the surface charge for bacteria to stick

Why is quorum sensing important in a biofilm?

Quorum sensing is the production of chemical signal molecules that increase in concentration as cell density increases When the concentration of signaling molecules is high enough, the bacteria alter gene expression creation and some functions of a biofilm are quorum sensing mediated

External parts of the biofilm may detach

Quorum sensing mediated: needed to increase surface area to volume, not enough nutrients Mechanical shearing: brushing your teeth

Irreversibly attached cells begin to replicate and produce substantial EPM

Quorum sensing molecules trigger cells to bind to the substrate and to each other, creating microcolonies (clusters of up to 50 cells) developing of our biofilm rapid growth and division and the production of the signal molecules that bacteria to grow more and faster and make EPM

Secondary colonizers attach and water channels form between adjacent microcolonies

Secondary colonizers partition the biofilm into niches along nutrient gradients and nutrient species quorum sensing tells them to come in channels are quorum sensing mediated bc if they are too close, the cells will starve. Trigger cells on the outside to stop producing too much EPM or to break off and float away

The NIH estimates that ___% of infections are caused by microorganisms growing in a biofilm

The NIH estimates that 80% of infections are caused by microorganisms growing in a biofilm

critical residence time

amount of time bacteria require to turn on enzyme systems to start producing that extracellular polymeric matrix (EPM)

biofilm formation long version

The first components associated with the surface or interface are not the microorganisms but organic molecules, salts in solution and solvated ions—that might be used as nutrients, electron acceptors, enzymatic cofactors, trace elements, etc.—are transported from the bulk electrolyte to the surface (e.g. metals) where they become adsorbed and subsequently retained by the heterogeneous structure of the surface. Almost immediately after a clean surface comes into contact with water, a complex layer or organic and inorganic deposits layer is formed [Mittelman M. W., 1985; Dreeszen P. H., 2003]. These compounds form a conditioning layer, which neutralize the surface charge (double layer) and the surface free energy. 2. Some planktonic (free living) cells are transported from the bulk electrolyte to the preconditioned surface. These pioneer cells become entrained within the boundary layer due to electrostatic attraction and physical forces, but no chemical binds take place [Dreeszen P. H., 2003]. 3. A fraction of the transported cells becomes adsorbed onto the preconditioned surface for a finite time and later desorbs (reversible adsorption). 4. Later on, desorption occurs. Desorption is mainly controlled by the shear stress caused by a flowing electrolyte; however there are other physical, chemical and biological factors, that independently or collectively may influence the separation process, such as the quorum sensing phenomenon (detection of critical cell density) related to cell-cell communication processes [Allison D. G. et al., 1999; Costerton J. W. et al., 1999; Dominguez-Benetton X., 2004]. 5. The microbial fraction that is able to remain adsorbed onto the surface becomes an irreversibly adsorbed film after a critical residence time. 6. The cells that became irreversibly adsorbed start to develop and replicate using nutrients from both the electrolyte and the metallic surface, increasing progressively the number of sessile cells, and hence the biofilm thickness and density. A substantial production of EPM promotes the biofilm cohesion. 7. New cells and matter attach into the developed biofilm (secondary colonizers) as it reaches a mature state. These secondary colonizers might metabolize wastes from the primary colonizers as well as produce their own waste which other cells may use. 8. External parts of a biofilm detach and return to the bulk electrolyte (mainly quorum sensing mediated). The detached cells might elsewhere reattach to a new surface or interface to develop a new biofilm or become incorporated in a previously established one [Videla H. A. 1996].

. Why are some obligate anaerobes able to grow in tissues (e.g., gum pockets) that are not completely free of oxygen?

They have some aerobes that produce waste they use as nutrients There are another type of obligate anaerobes that are encountered in the human body and are gram-positive, rod-shaped Clostridium spp. Their ability to form endospores allows them to survive in the presence of oxygen.

sorption

benefit of biofilms resource capture as bulk fluid flows over cell, some resources might stick to surface and enter the biofilm