Transcript PROTECTION OF MESOPORE-ADSORBED TYROSINE FROM

PROTECTION OF MESOPORE-ADSORBED TYROSINE FROM MICROBIAL
DEGRADATION BY PSEUDOMONAS AERUGINOSA
1
Stewart* ,
1
Daly ,
1
Thomsen ,
2
Zimmerman ,
1
1
Mathur ( York
Benjamin C.
Susanne
Ronna
Andrew R.
and Carolyn F.
College of
2
Pennsylvania, Department of Biological Sciences and University of Florida, Department of Geological Sciences)
PA was grown with different
combinations of mesoporous
and non-mesoporous alumina
with tyrosine (0.6-2.0 mM), and
placed within well culture plates
containing a calcium chloride
buffer (10ml) using the protocol
in Fig. 4.
A
1
2
3
Fraunhofer-Gesellschaft
Fig. 1 Molecular view of mesopores
0.2g MP-Al
1.0g NP-Al
0.2g NP-Al
B
C
0.2g MP-Al
0.2g MP-Al
+ PA
+tyr +PA
1.0g NP-Al
1.0g NP-Al
+PA
+tyr +PA
0.2g NP-Al
0.2g NP-Al
+PA
+tyr +PA
Fig. 4 Well plate setup.
MP-Al = mesoporous alumina;
NP-Al = nonporous alumina;
+tyr = with adsorbed tyrosine;
+Pa = with Pa
Conclusions
Biofilm
0.6
0.4
0.2
0
1/A 1/B 1/C
Planktonic Cells
Planktonic cells were harvested
from the wells using a pipette.
The remaining, attached biofilm
cells were stained with crystal
violet, excess stain washed, and
the remaining stain eluted with
ethanol.
The presence of planktonic and
biofilm cells was measured
spectrophotometrically.
Biofilm Cells
Fig. 3 Planktonic cells are free- floating and
biofilm cells are attached to surfaces
Relative absorbances were
compared to indicate Pa growth
under the different experimental
conditions.
3/A 3/B 3/C
Planktonic
Wells were incubated at 30 C,
and shaken at 50 rpm 7 days.
Fig. 2 Tyrosine structure
2/A 2/B 2/C
• Fig. Biofilm growth was only present in wells
containing non-porous minerals and tyrosine (2C and
3C).
• No biofilm formation occurred in wells containing
mesoporous minerals, both with & without tyrosine. *
0.6
Absorbance
• Mesopores are nanometersized pores found in soils and
sedimentary rocks.
• Organic materials can be
adsorbed into mesopores
• Adsorption of organic
material to mesoporous rocks
is better than adsorption to
non-porous rocks.
(Zimmerman)
• Sequestration of petroleum
products into mesopores
could be a mechanism to
prevent natural microbial
degradation of this vital
energy source.
• The bacterium Pseudomonas
aeruginosa (Pa) can grow in
the presence of a single
amino acid (such as tyrosine)
as an energy source.
(Thompson, Daly)
• Pa can grow as both
planktonic (suspended cells)
and biofilm (attached)
cultures.
• Tyrosine has an aromatic
structure that can adsorb to
mesoporous alumina
(Zimmerman).
• Alumina is a common mineral
in soils and rocks.
• The “Mesopore Exclusion
Hypothesis” states that
mesopores sequester organic
compounds from microbial
attack.
• In order to determine if
mesopore-adsorbed organic
material can be prevented
from supporting microbial
growth, we developed a
microbe-nutrient model using
Pa and tyrosine.
Pseudomonas
aeruginosa can not
utilize the nutrient
tyrosine for growth
when it is adsorbed
into mesoporous
alumina.
Results
Absorbance
Introduction
Methods
Hypothesis
• Pa can grow as both
planktonic and
biofilm cultures with
tyrosine as the sole
energy source.
• Pa does not grow as
planktonic or biofilm
cultures when
tyrosine is adsorbed
into mesoporous
alumina.
• Pa does grow as
both planktonic and
biofilm cultures
when tyrosine is
adsorbed to nonmesoporous
alumina.
• These observations
support our
hypothesis and the
mesopore exclusion
hypothesis.
0.4
Literature Cited
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1/A 1/B 1/C
2/A 2/B 2/C
3/A 3/B 3/C
• Fig. Planktonic growth occurred in the high
concentration(2C), nonporous wells containing Pa
and tyrosine, and (2B) containing Pa with no tyrosine.
• There was also significant growth in the NP low
concentration (3C) wells, containing Pa and tyrosine.
• No planktonic growth occurred in wells containing
mesoporous minerals, both with & without tyrosine. *
* See Legend in Figure 4
• Lewis, K. 2001. Mini Review: Riddle of
Biofilm Resistance. Antimicrobial
Agents and Chemotherapy. 45: 9991006.
• Mayer, L., et al. 2004. Organic Matter in
Small Mesopores in sediments and
Soils. Geochemica et Cosmochimica
Acta. 68: 3863-3872.
• Nam, K. and Alexander, M. 1998. Role of
Nanoporosity and Hydrophobicity in
Sequestration and Bioavailability: Tests
with Model Solids. Environmental
Science & Technology. 32: 71-74.
• Zimmerman, A.R., et al. 2003. The Effect
of Mineral Mesopores on Organic Matter
Adsorption. For Submission to: Organic
Geochemistry