The colonization and metabolic patterns of airborne and oral bacteria
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.
, 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
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,
is commonly found in gastrointestinal and vaginal tract as
well. Another common species in the mouth is
. 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
they form natural flora in our oral cavity. By producing lactic acid from
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
, a well-