Ubiquity of Bacteria

Topics: Bacteria, Eukaryote, Archaea Pages: 2 (545 words) Published: May 5, 2011

Bacteria can be found everywhere on the earth. Bacteria are single-celled organisms that lack a nucleus, mitochondria, and chloroplasts and are surrounded by a cell wall containing a peptidoglycan layer. They are defined by their small size and wide range of shapes.

In this experiment we separated organisms in a mixed culture to study the colony morphology and physical characteristics and determine which organism was present in higher numbers, as determined by a colony count. Sterile cotton swabs were used to sample the classroom telephone, light switch, cell phone, and a student’s tongue. After carefully swabbing each site, we inoculated separate Petri dishes and a test tube of nutrient broth. A blood agar plate was exposed to bacteria by coughing on it. The plates were then incubated at 37ºC for 48 hours.

The light switch and telephone were contaminated with both bacteria and mold which produced turbid tubes of broth. However, the sampling of the student’s tongue yielded a higher colony count with a more turbid tube of broth in comparison than the other places that were sampled. This caused a rejection of our hypothesis that the telephone and cell phone would contain the most bacteria.

Bacteria can be found everywhere. They are so widespread that they can be found in such extreme environments as the top of mountains, the bottom of oceans and even the surface of our skin. Bacteria are single-celled microorganisms that can exist as independent organisms or in conjunction with a host as a parasite. A bacterium lacks a nucleus, mitochondria, and chloroplasts; however, it still manages to carry out respiration and photosynthesis. Bacteria are defined by their cell structure and small size. Their cell wall is made up of peptidoglycan. Bacteria come in many different shapes including rods, spheres, and spirals.

Since bacteria do not exist in pure cultures in the environment, they need to...
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