Batting Biofilms - Assignment Example

Scientific American Current Issues in Microbiology Article: “Battling Biofilms” Due 11:59 PM on Monday, February 6th Each question is worth 1pt. 1. Some bacteria produce toxins or diseases only when the bacteria are growing as part of a biofilm. Explain how bacteria might use signaling molecules to control the genes that code for virulence. Microbes are capable of causing may stubborn infectious diseases after arranging themselves into complex tenacious films called the biofilms that can be nearly impossible to eradicate with conventional antibiotics.

In the past few years, medical researchers have discovered that the microorganisms in biofilms depend critically on their ability to signal one another. Bacteria are known to adhere to the surface in order to form a biofilm and in the process they manufacture hundreds of proteins not found in free-floating cells. These proteins are also involved in the shuffle that bacterial cells undergo just after they settle on the surface but before they fix their positions. If genes which are responsible for the formation of these adhering protein molecules are deleted the bacteria are unable to form biofilms.

However, it is now proved that bacteria form biofilms after communicating with each other through signal molecules, for e.g. in P. aeruginosa the relevant signaling molecules are acylated homoserine lactones which each cell produces at a low level, when enough cells assemble the concentration of these compounds increases which in turn trigger the activation of certain genes, the mechanism is known as quorum sensing, which is critical for the formation of biofilms. Since biofilms formed by P. aeruginosa is responsible for causing cystic fibrosis pneumonia, i.e. they turn virulent (disease causing).

algC gene is responsible to synthesize alginate, the gelatinous polymer that makes extracellular matrix. Thus, signaling molecules to control the genes that code for virulence.2. Describe strategies scientists might employ to interfere with each of the five stages of biofilm formation.During stage 1 when the bacterial cells move or swim freely and arrange themselves in cluster in order to form a biofilm; Attack strategy is employed that coats the molecules and block or disrupt microbial arrangement or attachment.

During stage 2- when the collected cells begin producing a gooey matrix; Attack strategy is employed which coat the surfaces with substances that interfere with the matrix production so that film is not formed.During stage 3- when the cells signal one another to multiply and forma a microcolony; Attack strategy is employed which delivers signal blockers and abort the biofilm formation.During stage 4- when chemical gradient arise and promote the coexistence of diverse species and metabolic states; Attack strategy is employed which delivers multiple antibiotics or disinfectants to undermine the varied survival strategies of biofilm cells.

During Stage 5- some cells return to their free-living forms in order to form a new biofilm; Attack strategy is employed to induce cells to detach, then swamp them with antibiotics or antibodies.3. Scientists know that most bacteria in nature live in biofilms. Why did it take scientists almost 150 years to come to this understanding?Microbiologists took a very long time to size up the microbes in the biofilm. Since the establishment of germ theory, in the late 19th century by Robert Koch, bacteria were envisioned as single cells that float or swim through some kind of watery habitat, perhaps part of human body.

The concept of biofilm formation came from the investigations that examined microorganisms under special microscopes and when cultured cells were observed suspended in a fluid droplet. Since microbes are studied under laboratory conditions, which are quite different then natural environment it was difficult to formulate the concept of biofilms.4. How is it that regions within a biofilm can differ in chemical content?A biofilm is built of countless groupings of cells separated by a network of open water channels.

The fluid coursing through these tiny conduits bathes each congregation of microbes providing dissolved nutrients and removing waste products. The cells situated on the outside of a microcolony are well served by this plumbing system, but those in the interior are largely cutoff. The dense aggregation of cells surrounding them and the organic matrix that cements things together act as barriers to water flow. So the cells inside the colony behave in a different manner and supply of nutrients is not uniform in the biofilm, any substance will find tough to reach the center of the microcolony if it reacts with the matrix material.

Such chemical activity gives rise to small scale environmental changes within a biofilm. As oxygen concentration also varies in the microcolony, the physiological alteration in the cellular environment is observed which is responsible for variation in chemical content.5. Why is it that the red algae of Botany Bay do not get covered in a biofilm even though there are thousands of species of bacteria living in the same water? D. pulchra, a red algae of Botany Bay uses chemicals called substituted furanones to keep free of biofilms6.

What are some of the reasons why furanones may be used in the future to prevent biofilm production on human medical devices? D. pulchra, a red algae of Botany Bay uses chemicals called substituted furanones to keep free of biofilms. It is now launched by a company, Biosignal, to produce protective coatings that incorporate substituted furanones for application to ship hulls and aquaculture equipment. Furanones are nontoxic and stable in the body and therefore finds application in preventing biofilm development on human medical devices.7. Explain briefly the four steps involved in forming a biofilm.

Stage 1- bacterial cells move or swim freely and arrange themselves in cluster in order to form a biofilm.Stage 2- the collected cells begin producing a gooey matrix.Stage 3- the cells signal one another to multiply and forma a microcolony.Stage 4- a chemical gradient arise and promote the coexistence of diverse species and metabolic states.8. A scientist claims that cows eat bacteria not hay. Explain how the idea of biofilms confirms the scientist’s statement. A biofilm is formed on fodder after cows or other ruminants eat it.

These films are initially made up of organisms that digest the cellulose in plant matter and produce organic compounds called fattyacids. A feedback mechanism works when these cellulose-eating bacteria have generated enough fatty acids to inhibit their own growth, mobile cells or Treponema and other species invade the biofilm and begin using these very substances to fuel their own metabolism. The forage material gradually disappears, being converted into a mass of bacteria that the animal digests later on.

Thus Scientist has wisely said that the cows subsist on bacterial biofilms, not hay.