Inflammatory Response

A Small Proportion of Bacteria Found in the Human Body

Bacteria In Pond Water

Final Product Ideas

For the rest of my ISP, I am planning on synthesizing the information I have gathered on bacteria in an essay no more than 4000 words, possibly in the form of a thesis. Here is a short snippet from my essay so far:

The diversity of bacteria is sustained by their short generation span. Constantly adapting to changing environments, they have the ability to have an omnipresent impact on human life, as well as on the lives of other animals.

The intestinal bacterium E. coli is the epitome of such diversity. Through extensive studies, E. coli has presented most of the information we now know about bacteria. The double-stranded, circular DNA molecule is important to the bacterial genome: it is tightly packed in a region called the nucleoid and does not contain a binding membrane. Another characteristic that sets bacteria apart from eukaryotic organisms is that they contain several plasmids that are not necessary for survival, but may be beneficial in harsh environments—another factor that adds to the malleability of these microbes.

Bacteria, including E. coli, are also extremely successful because of their ability to proliferate so rapidly through asexual reproduction. It has been calculated that approximately nine million E. coli genes are mutated through this process per day per human host. This data supports the conclusion that bacteria can adapt to an environment through genetic mutation; those that survive will go on to reproduce. Though mutations are a major source of variation within a bacterial population, a process called genetic recombination can add more diversity to a population.

One study involving E. coli proves this. Wild-type E. coli (non-mutant) can survive only on a medium of glucose. However, two mutant strains, one of which cannot produce tryptophan, and the other that cannot synthesize arganine. When both the strains were mixed together and incubated on a minimal medium, growth occurs, showing that genetic recombination has occurred, making the two individual strains successful in an environment containing a minimal nutrition source.

In addition to being so versatile independently, bacteria can be used by scientists to exemplify certain genes present in non-bacterial organisms. A certain gene of interest (from any cell, including eukaryotic ones) can be isolated and inserted into a plasmid from a bacterial cell. The plasmid containing the gene of interest can be placed back into the bacterial cell, which is then cloned. When the bacteria reproduce, only some express the gene of interest. This strain of the bacteria can then be used for a variety of things, such as pest resistance for plants, or the treatment of stunted growth in animals.

Another piece of evidence showing that bacteria are extremely successful on earth is that bacteria were some of the first organisms to appear on the planet, about three thousand five hundred million years ago. The fact that these seemingly simple organisms have kept their genus intact for 3500 million years is undeniable proof of their complexity. As proof of their diversity, about five thousand species are currently known. These species may differ in their shape (coccus, bacillus, helical), motility (flagella, spirochetes), function, and nutritional or metabolic diversity.

            Though popular culture has lead us to associate the term bacteria with harm, many bacteria are actually quite useful. E. coli, a previously mentioned example, is useful in research, but is also found in the human intestine... (Note: I am not completely done with this paragraph yet…)

            These deceptively simple creatures have immensely complex ways of communication as well. Bacteria secrete autoinducers (chemical signal molecules) in order to communicate. These molecules can regulate gene expression and behavior by detecting the concentration of a certain autoinducer. This method of communication can allow bacteria to act like multicellular organisms. For example, on study conducted by Bonnie Basselor and her peers…(Note: I am not completely done with this paragraph yet…)

            At this point, my study of bacteria appeared somewhat broad, so I attempted to narrow my focus from the diversity of bacteria to developing methods of preventing harmful bacteria from entering human systems. Previously, an antimicrobial by the name of Triclosan, or Microban was used. Triclosan proved to be effective, but there were soon rising concerns about the toxicity of triclosan because it is a possible carcinogen, and is closely related to dioxin. Over the years, the use of this antimicrobial declined.

            However, this brief study of antimicrobials introduced me to another of the wonders of bacteria: triclosan also brought up concerns because bacteria easily gained antibiotic resistance to it. The concern that they adapted so easily, in just a few generations, amazed me and uncovered a whole new layer of versatility in the world of bacteria.

Please note that the above fragment is only a small part of my entire essay. The full essay is much more detailed, but I do not want to release the entire paper all at once. 

More Research

I really want to contact this professor: http://www.jhsph.edu/faculty/directory/profile/3936/Halden/Rolf_U. That would just be amazing... I could learn so much!

Other Antimicrobials

I discussed triclosan in the previous post... I also found some other substances that are associated with antimicrobial properties:
Australian tea tree oil
Grapefruit seed extract
Pine oil
Thyme oil (thymol)
H2Orange2 (a combination of hydrogen peroxide and orange oil)
Activated Triclosan (supposedly more efficient than the "traditional" version)

The Controversy over Triclosan

Triclosan is an antimicrobial agent used in many household antibacterial products. A controversy presides over the use of this agent, however.

First, I would like to address the issues associated with Triclosan, and its function in our bodies. Triclosan blocks the active site of the enoyl-acyl carrier protein reductase enzyme. This enzyme is an essential enzyme required for the fatty acid synthesis in bacteria, and when Triclosan is present, it acts as a competitive inhibitor for the active site. As a result, the bacteria is prevented from producing the fatty acids needed for growth and reproduction, which in turn kills the bacteria. To many, this would make Triclosan a reasonable antimicrobial agent. However, some studies show that when exposed to water and UV rays, they are transformed into a potential carcinogen, Dioxin. I will need to conduct more research on this in order to understand how this occurs.

Also, this is a mental note to remember to look up the chemical structure of Triclosan and Dioxin and compare them...