Post on 25-Feb-2016
description
Genetic Profiling of Oncoid Stromatolites from the Phosphorus-
Limited Rio Mesquites in Cuatro Cienegas, MX
Alisa GlukhovaNASA Space Grant Symposium
April 21st 2012Mentors: Amisha Poret-Petterson
&Ariel Anbar
Introduction• Phosphorus (P) is an essential element for all
organisms • P is an important component of biological
molecules and often a limiting nutrient
DNA RNA ATP Phospholipids
Introduction
• Stromatolites are layered microbial mats
• Biological growth and mineral deposition
• Interaction between microbial growth, calcification, and P availability
Introduction• Rio Mesquites stromatolites
live in an environment with the lowest P content (0.6 mmol L-1) reported in continental waters
• Stromatolites thrive in Rio Mesquites because P limitation has decreased the population of snails and other grazers
Hypotheses 1. The microbial community is P-
limited and will remain the same, but increase in size due to growth (alleviation of P-limitation)
2. The microbes are adapted to low P conditions and a species composition change may occur with addition of P.
3. There could also be a combination of both.
Original Community
1 2
3
MethodsTreatments: • Control (no addition) • Low Phosphorus (5 µM N2HPO4) • High Phosphorus (10 µM N2HPO4) • Carbon (53 µM acetate + 53 µM glucose) • Low P + Carbon • High P + Carbon
Methods
• PCR (8FFAM/1492R)• Restriction Digest of PCR
Products• Capillary Electrophoresis
• T-RFLP
Microbial Community Fingerprint
T-RF
Fluo
resc
ence
Results
ResultsControl
LP
HP
CLP
CHP
• T-RFs become more complex with C addition
• Growth ofheterotrophic bacteria
Summary & Future Directions• PCR-amplified and restricted bacterial 16S rRNA
genes from oncoid stromatolites incubated with additions of C and P
• Most complex T-RF patterns were obtained with organic C addition, suggesting that the population of heterotrophic microbes in stromatolites increased.
• Perform a detailed analysis of these T-RF profiles to confirm these initial findings
• Compare T-RFLP patterns to stromatolite chemical compostion data (C, N, and P)
Acknowledgements• Jessica Corman• James Elser• Ariel Anbar• Christie Sabin• Zuri Martinez