Why is there so much microbial diversity in NJ and Beyond?
Rutgers University, Lee Kerkhof
Institute of Marine and Coastal Sciences
Thursday, March 29, 12
Overview of the seminar
•Background on how we do oceanography and a small lecture
•Measurements of the coast of New Jersey •Assessment of active bacteria in the Orinoco River Plume
•Determination of active bacteria in the subsurface
Then, I get to revisit these sites again with a different methodology
Thursday, March 29, 12
TextText
Winch and “A” frame
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Niskin Bottles to collect water samples at depth
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Look at all the hard hats and safety gear
Floats for equipment going over the side
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Inside the ship in the science labs. All the space is used.
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ASM workshop--2000
Why study bacteria in the ocean?
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How biologists understood the tree of life in 1866.
3 main groups of organismsBased primarily upon morphology
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Anoxic hypolimnion sample
Microbial Life-’02 Perry et al.Thursday, March 29, 12
Electron micrograph of bacteria collected off the coast of Hawaii
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Viable counting of bacteria by serial dilution and plate count
Microbial Life-’02 Perry et al.
Thursday, March 29, 12
Counting the number of viable cells by serial dilution and plate count
Microbial Life-’02 Perry et al.Thursday, March 29, 12
Jannasch & Jones, 1959
Results of bacterial counts with 6 methods
Thursday, March 29, 12
What is Meant by Molecular Ecology?
Using methodology that identifies specific molecules in a complex mixture to identify
specific groups of microorganisms to address ecological questions
Target molecules can be:•Unique pigments or 2o metabolites•Lipids•Proteins•Nucleic Acids
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What biomolecules can we work with?
Microbial Life-’02 Perry et al.
Thursday, March 29, 12
Traditional Clone and Sequence Method
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UniversalAncestor
BacteriaArchaea
Eukarya
Pyrodictium
Thermoproteus Thermococcus
Methanococcus
MethanobacteriumHalobacterium
Thermoplasma
Methanopyrus
Aquifex
Thermotoga
Flavobacteria
Cyanobacteria
ProteobacteriaGram-Positive Bacteria Entamoebae
Slime MoldsAnimals
Fungi
Plants
Ciliates
Flagellates
MicrosporidiaDiplomonads
Archaeoglobus
Green Non-Sulfur Bacteria
Sulfolobus
Ignicoccus
The Ribosomal RNA SSU tree of life
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Problem
Why are there so many bacterial species in the ocean [or anywhere else] ?
There should be competitive exclusion, i.e. the best adapted
organism out competes all the others.
Hardin 1960
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The solution to the Paradox of the PlanktonHutchinson 1961
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The solution to the Paradox of the PlanktonHutchinson 1961
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Stable Co-existence--resource partitioning
Chesson 2000
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Stable Co-existence--resource partitioning
Chesson 2000
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Stable Co-existence- [selective predation]
Chesson 2000
Hutchinson 1961
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Interesting question
Do bacteria in the coastal ocean of New Jersey experience rapidly changing patchy niches that could account for
microbial diversity?
Thursday, March 29, 12
Interesting question
Do bacteria in the coastal ocean of New Jersey experience rapidly changing patchy niches that could account for
microbial diversity?
Test this with activity measurements of bacteria in the water column on a diel
cycle.
Thursday, March 29, 12
Results from the GRIST Experiment
The GRIST study aimed to target the active bacteria in the coastal ocean and assess the relationship between traditional rate measurements and gene-based methodologies for linking processes from the molecular to the global scale.
LEO-15
1
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Almost-diel study times indicated by the 2 orange boxes
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Five approaches using RNA/DNA based methods to determine activity
1. mRNA analysis2. MICROFISH analysis3. BrDU incorporation4. Ribosome fingerprinting5. Stable Isotope incorporation
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What biomolecules can we work with?
Microbial Life-’02 Perry et al.
Thursday, March 29, 12
Universal Ribosomal rRNA content vs. Growth Rate
2.01.51.00.50.00
3
6
9
12
Specific Growth Rate (h-1)
RN
A/D
NA
Kerkhof and Ward, 1993Thursday, March 29, 12
What can we predict?
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How does Terminal Restriction Fragment Length Polymorphism work?
Restriction Enzyme Digest
ABI Software AnalysisOnly labeled fragments appear as peaks
PCR with fluorescent primers
Gene 1
Gene 2
Gene 3
Gene 4
Gene n
Gene n+ 1
Size separate on automated sequencer
A B
Sample
Purify DNA
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Ribosomal RNA fingerprints during the GRIST experiment
TRFLP Size (in base pairs)
Sign
al S
treng
th
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Incorporation of stable isotopes into DNA and separation by ultracentrifugation
4
Radajewski et al 2000, Nature 403: 646–649Thursday, March 29, 12
Semi-conservative replication of DNA
Meselson and Stahl 1958, PNAS 44: 671-–649
generations15N
14NThursday, March 29, 12
Map of Sample Sites
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TRFLP fingerprints of nosZ genes from benzoate fed slurries from Norfolk and LEO
Gallagher et al., 2005 AEM 71:5192-5196 TRFLP Size (in base pairs)
Sign
al S
treng
th
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Increase in TRFLP peak areas through time for LEO-15 and Norfolk incubations
Gallagher et al., 2005 AEM 71:5192-5196 Thursday, March 29, 12
Venezuela
Caribbean Basin
Trinidad Tobago
St. Lucia
Puerto Rico
Guadalupe
Satellite surface Chla
5-10 mg/m3
2-5 mg/m3
0.5-1.5 mg/m3
15o N
65o W
10o N
60o W
Orinoco River Plume7
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Enrichment culture/ resource partitioning
Wawrik et al., 2005Thursday, March 29, 12
13C amino acid uptake 13C Pigment uptake
112 bp85 bp 140 bp
13C protein uptakeStation 12
Carbon utilization patterns of bacteria in the plumeL. Kerkhof, C. Ferraro, L. McGuinness
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Far Plume Site
L. Kerkhof, C. Ferraro, L. McGuinness
Nitrogen utilization patterns of bacteria in the plume
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First Conclusions
1) Ribosome fingerprinting can distinguish active from resident bacteria.
2) Not every bacterial group is behaving uniformly in the field. But, there are some repeating patterns indicating non-randomness.
3) Roughly 25-50% of the microbial population are not growing in the Mid-Atlantic Bight and the Orinoco River Plume (i.e. DNA signal, no RNA signal).
4) So far, little correlation to measured environmental parameters.
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Conclusions
A) Whether there is resource partitioning among bacteria depends on your environment.
B) The role of predation in structuring the community plays a more important role than typically appreciated.
C) Elucidating the microbial food web using molecular tools is just in its infancy. There is so much more to learn!
Thursday, March 29, 12