Chapter2: Aquatic Plants And Animals
Section: Chapter Questions
Problem 2KA
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Transcribed Image Text:You have found media that support growth of pure cultures of ETPUM in your laboratory. The recipes for
these media are shown below:
Table 2
Medium #1
Medium #2
5 g yeast extract
10.5 g K HΡΟ4
20 g tryptone extract
4-5 g KH2PO4
I g MgSO4
10 g polyurethane
Il H20
0.5 g NaCl
3.6 g glucose
Il H20
Growth in these media:
Table 3
Growth
Medium #1
Medium #2
ETPUM growth-aerobic
+
ETPUM growth-anaerobic
E.coli growth-aerobic
+
E.coli growth-anaerobic
You are excited because, in Medium #2, ETPUM utilizes polyurethane as its energy source and its sole
source of carbon and nitrogen, a finding that raises the possibility that ETPUM could be a useful tool for
bioremediation of polyurethane-containing wastes (in landfills, etc.). You have also made some progress in
characterizing the central metabolic pathways and related biochemical activities of ETPUM. In particular,
you have discovered that:
• ETPUM secretes an enzyme (polyurethanase) that catalyzes degradation of polyurethane, generating
citric acid (citrate) as a product.
• The cytoplasmic membrane of ETPUM contains an ABC transport system capable of transporting
citrate across the membrane at the expense of 4 ATP molecules (hydrolyzed to form ADP and
phosphate) per molecule of citrate transported.
• The cytoplasm of this organism contains all of the enzymes required for glycolysis, and for the TCA cycle.
• The cytoplasmic membrane of ETPUM contains proteins that form a functional electron-transport
pathway (that uses O2 as the terminal electron acceptor).
Transcribed Image Text:Questions
1. Which medium would you consider to be "complex" and which "defined"? Which is "rich" and which
is “minimal"? Explain your answers.
2. Given that polyurethane is a huge polymer (MW >>100,000 Daltons), why is it important that the
polyurethanase is a secreted enzyme? If we assume that the polyurethane is the source of energy for the
"ELVIS Meltdown!" by Stewart, Smith and Shields
Page 7
organism, how can material (carbon atoms) from it find its way into the central metabolic pathways of
this microbe? What is the "entry point"? What happens after its entry into the metabolic pathway?
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