Contamination or Brilliant Accident? Isolation of a Polyethylene Degrading Microorganism

After reading the article “Biodegradability of polyethylene by bacteria and fungi from Dandora dumpsite NairobiKenya”by Muhonja and colleagues, you were inspired to try a similar experiment in the lab. You generated a
stock solution of artificial media, as described in the paper. Briefly, the media was prepared using 0.1%
(NH4)2SO4, 0.1% NaNO3, 0.1% K2HPO4, 0.1% KCl, 0.02% MgSO4,and 0.001% yeast extract in 1000ml of
distilled water. To make the stock solution easier to use in the lab, you added in the sheets of polyethylene and
then stored the media on the lab bench. After several weeks, you took down the stock solution to add a mixture
of bacteria and noticed that the solution had become contaminated and turbid, while the amount of
polyethylene appeared to have decreased. Use this described scenario to answer the following questions.
1.How would you characterize the artificial media? Is it complex, rich, minimal, defined, enriched, selective,
differential? Does the characterization change once the polyethylene is added?
2.What method will you use to determine the number of cells in the turbid media?
3.Since the stock solution of polyethylene artificial media is contaminated, how could you attempt to isolate a
polyethylene-degrading microorganism from the stock solution?
4.Once you isolate the organism, you might perform a growth assay to generate a growth curve for that
organism. Sketch a typical growth curve and label what occurs at each stage of the growth curve.
5.Assuming the microorganism can also grow in Luria Bertani media (see Table 4.1in the textbook), how might
that growth curve differ from the one you sketched above? What might be causing the difference in the
generation times for growth on polyethylene artificial media versus Luria Bertani media?
NOTE:
1) The question is related specifically to set up experiments. Hence, while reading the citation focus on the
materials and methods rather than discussion. Also, do not miss reading the abstract and introduction of
citation.
2) Make sure you answer each question separately and not as a paragraph.
Citation: Muhonja,Christabel N., Huxley Makond, Gabriel Magoma, and Mabel Imbuga.2018. Biodegradability
of polyethylene by bacteria and fungi from Dandora dumpsite Nairobi-Kenya. PLoS
One13(7):e0198446.https://doi.org/10.1371/journal.pone.0198446
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6034791/