Investigating Interactions between Lignin and Marine Microbes Connor Stonesifer Mentor: Natasha...
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Transcript of Investigating Interactions between Lignin and Marine Microbes Connor Stonesifer Mentor: Natasha...
Investigating Interactions between Lignin and Marine
Microbes
Connor StonesiferMentor: Natasha McDonald
C.D.O.M• CDOM= large factor in regulating the
underwater light field– Absorbs light
• Problem: We don’t really know what it’s comprised of!
• Problem: We don’t really know how microbes interact with it!
• Clue: Lignin is a constituent of CDOM
Lignin• Phenolic organic polymer
– Aromatic and a constituent of CDOM
• Derived from cell walls of woody vascular plants (terrestrial origin)
• 9 standard phenol monomers, no standard composition
• Found in all natural waters (including open ocean)
Experimental Questions
• Can lignin persist in a marine microbial environment?
• Can lignin be used a nutrient source by marine microbes in oligotrophic waters?
• How does lignin’s molecular complexity affect its ability to be degraded by marine microbes?
• Are the by-products of lignin degradation more or less labile than the by-products of the metabolism of simpler nutrients?
Experiment 2 Set Up
Control: 70/30 Mix Filtered and Unfiltered Seawater
GNP: + Glucose (10uM C)
+ NH4Cl (1 uM)+ K2HPO4 (0.1 uM)
LNP: + Lignin+ NH4Cl (1 uM)+ K2HPO4 (0.1 uM)
Lignin: + Lignin (10 uM carbon)
Experiment 2 SamplingControl
GNP
Lignin
LNP
CDOM Lignin Concentrations (T0, 10 days, and 30 days)Bacterial Abundance DOC FISH probes DNAEEMS
Experiment 2 Results: Plot of Control/GNP
Plot 2: Lignin and LNP1
ligmean = 0.5542; ligstd = 0.1290; lnpmean = 0.5808; lnpstd = 0.1199
Changing Absorption Spectra of Lignin Over Time: T4 (45 hours)
Changing Absorption Spectra of Lignin Over Time : T5 (62 Hours)
Changing Absorption Spectra of Lignin Over Time : T7 (86 Hours)
Changing Absorption Spectra of Lignin Over Time : T8 (93 Hours)
Changing Absorption Spectra of Lignin Over Time: T9 (110 Hours)
What do we know now?
• We now know lignin is being removed by some process from the absorbance spectrum
Now it’s time to look at what bacteria are doing...
16
0 2 4 6 8 10 120.0E+00
2.0E+05
4.0E+05
6.0E+05
8.0E+05
1.0E+06
1.2E+06
1.4E+06
1.6E+06
CDOM14-2 (Lignin Experiment 2) Bacterioplankton Counts
C1C2L1L2LNP1LNP2GNP1GNP2
Time (Days)
Bact
eria
/mL
Standard error bars represent standard deviation (N=2)
GNP showed ~8x increase
LNP showed ~3-3.5x increase
Lignin showed ~2.5x increase
Controls showed ~1.5x increase
Conclusion
• Our preliminary studies strongly suggest that marine bacteria can use lignin as a nutrient source.– Lignin therefore may be a carbon source for
bacteria in oligotrophic waters.
• Nitrogen and phosphorus are not an important nutrient amendment for bacterial metabolism of lignin, a complex nutrient substrate.
• Future analysis should examine the by-products of lignin metabolism, the bacterial communities involved, and the mechanism for degradation
THANK YOU!