bisc lab report #2 example Bacteria_paper_2007

bisc lab report #2 example Bacteria_paper_2007 - 1 The...

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The colonization and metabolic patterns of airborne and oral bacteria Introduction Domain Bacteria, which consists of autotrophic photosynthetic cyanobacteria and heterotrophic eubacteria includes the most ancient and diverse life forms on earth. These prokaryotic organisms have evolved from 3.5 billion years ago (Campbell and Reece, 2005). It has been hypothesized that Bacteria domain has given rise to Eukarya domain through endosymbiosis of mitochrondria and chloroplast. Together with Archaea domain, these three domains encompass all past and existing life forms on earth. Bacteria reproduce asexually through the process of binary fission, in which the parent cell divides into two daughter cells, which can undergo further divisions. Escherichia coli , the fastest reproducing bacteria, can complete 1 cycle of division within 20 minutes. If provided with unlimited nutrients, a single bacterium can divide continuously and form colonies with ~10 9 cells. In this study, we attempt to observe the patterns of colonization of two groups of eubacteria, oral and airborne bacteria. Human oral cavity is inhabited by the lactic acid bacteria, which are Gram-positive anaerobic bacteria that convert lactose and other sugars to lactic acid through fermentation. Besides being found in our mouth, Lactobacillus acidophilus is commonly found in gastrointestinal and vaginal tract as well. Another common species in the mouth is Streptococcus mutans . These microbes readily colonize and form “indigenous microbiota”, or natural flora, on the surface tissues (skin and mucous membrane) of the host organisms. Under most circumstances, the mixtures of these microorganisms that form natural flora establish commensal, or harmless, relationship with the host. In some cases, they benefit the hosts by maintaining certain conditions that inhibit the growth of pathogens (Lum et al., 2007). In the case of Streptococcus and Lactobacillus, they form natural flora in our oral cavity. By producing lactic acid from sugars, Lactobacilli establish an acidic environment that deters harmful pathogens. However, because of the excess lactic acid produced, they are also responsible for the formation of dental plaque and cavities. The second group of bacteria observed in this study is airborne bacteria, which include any bacteria that are capable of traveling from host to host and surface to host by means of air or physical contact. One of major airborne bacterial clade is the Streptococcus genus. S. pneumoniae , a well- 1
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recognized disease pathogen, is the primary cause of bacterial pneumonia, otitis media and meningitis. S. pneumoniae is often found in the nasopharynx lining and can be transmitted from person to person by saliva droplets through the air. Another common airborne bacteria is Staphylococcus aureus, or golden staph. This notorious spherical grape-like bacterium causes a wide range of skin infections.
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