Bacteria are able to metabolize an enormous amount of different compounds for
energy, due both to their physiological and genealogical adaptations.
can be very useful for a variety of purposes, including dissimilatory metal reduction, soil
enhancement, and for this experiment, biodegradation.
Microbes are capable of breaking
down many environmental toxins, using their carbon as an energy source for their own
The organic toxin used in this experiment was 2,4 Dichlorophenoxyacetic
Acid (2,4-D), an herbicide.
By growing a culture in a medium containing 2,4-D,
microbes can be enriched to grow in a medium with the toxin as the sole carbon source,
therefore also enriching the breakdown of 2,4-D in the medium.
The ability to utilize a number of compounds as energy sources and to survive
many different types of environments takes constant evolution, and microbes are set up to
evolve their DNA sequences through horizontal gene transfer.
Bacteria are able to easily
accept and exchange genes from and with their environment, through processes of
conjugation, transduction, and plasmid and transposon integration.
Another type of
genetic sharing involves triparental mating.
Triparental mating involves three different
strains of cells: the selected recipient strain, a strain with a mobilizable plasmid, and a
strain containing a self-transmissible plasmid.
The mobilizable plasmid, p1062a,
contains the Tn5 transposon, containing the desirable trait of kanamycin resistance.
plasmid is not capable of transferring itself, but it can be transferred by another plasmid
in the same cell.
The self-transmissible plasmid pRK2014 was used in this experiment,
and it does mobilize the p1062a plasmid, we can assume the two share an