Chosen Bacteria

Here is some background on the bacteria chosen for the experiment (I have one more to add to the paper but did not finish in time for the blog post):

Escherichia coli. This bateria was chosen as a representative of normal intestinal flora. E. coli are described by Nanninga, 2001 as coliforms, gram-negative bacilli that are 0.8μm in width by 1.0 − 2.0μm in length. These bacteria are peritrichous, they have flagella that grow from many places on the cell surface, indicating their motility.

E.coli is comprised of a large and diverse group of bacteria that are found throughout the environment (CDC, 2020). Most strains are apathogenic and such strains will be used as the experiment will measure structural aspects of the bacteria not related to virulence or pathogenicity.

Pseudomonas aeruginosa. This bacteria was choose as a representative from the blood. Wu and Li, 2014 describe P. aeruginosa as an aerobic gram-negative bacillus (rod-shaped) 0.5 − 0.8μm in width by 1.5 − 3.0μm in length. These bacteria are motile and posses a single polar flagellum. Of note is that P. aeruginosa is believed to be one of the few true pathogens for plants, and as such the results will form a dual experimental role.

Regarding safety, Wu and Li, 2014 adds, P. aeruginosa is "the epitome of an opportunistic pathogen of humans", meaning that it takes advantage of host defence deficiencies (in the form of disease like cystic fibrosis) or breakdowns (burns and wounds). Any riks of infection can be controlled by observing proper isolation procedures, aseptic technique, and careful cleaning and monitoring of instruments and equipment used.

Staphylococcus epidermidis. This bacteria chosen as representative of normal skin flora. Detailed observations by Kloos and Schleifer, 1975 show S. epidermidis is an anerobic gram-positive cocci that is singly 0.5 − 1.0 μm in diameter but usually is found in pairs or tetrads. Colony growth is gray-white in color, circular, and raised with a smooth margin. Notably, S. epidermidis can be distinguished from other staphylococci primarily by its cell wall composition, colony morphology, growth on NaCl agar, and, to a lesser extent, on the type of lactic acid produced as well as growth in thioglycolate medium.

Additionally, this species was chosen as, in contrast to Staphylococcus aureus, the virulence properties associated with S. epidermidis are few (Fey & Olson, 2010). So standard microbiological aseptic techniques will be sufficient for the safe handling of the bacteria.