Exploring the microbe-mediated soil H² sink : a lab-based study of the physiology and related H² consumption of isolates from the Harvard Forest LTER

Atmospheric hydrogen (H²) is a secondary greenhouse gas that attenuates the removal of methane (CH⁴) from the atmosphere. The largest and least understood term in the H² biogeochemical cycle, microbe-mediated soil uptake, is responsible for about 80% of Earth's tropospheric H² sink. A recent discovery of the first H²-oxidizing soil microorganism (Streptomyces sp. PCB7) containing a low-threshold, high-affinity NiFe-hydrogenase functional at ambient H² levels (approx. 530 ppb) made it possible to identify a model organism to characterize microbial H²-uptake behavior. In the present research, several strains of Streptomyces containing the high-affinity NiFe-hydrogenase were isolated from the Harvard Forest LTER and used to characterize H² uptake alongside analysis of their life cycles. It was found that containing the gene encoding for the specific hydrogenase predicted H² uptake behavior in the wild Streptomyces strains and also in more distantly related organisms that contained the gene. The H² uptake rates were correlated with the microorganisms' life cycles, reaching a maximal uptake corresponding with spore formation. Understanding how environmental conditions, organismal life cycle, and H² uptake are connected can help reduce the uncertainty in atmospheric models. With the rise of H²-based energy sources and a potential change in the tropospheric concentration of H² , understanding the sources and sinks of this trace gas is important for the future.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2012

Author dc:creator

• Rao, Deepa,Ph.D.Massachusetts Institute of Technology.

Advisor dc:contributor.advisor

• Laura Meredith and Ron Prinn.

• Earth, Atmospheric, and Planetary Sciences.

Statement dc:rights

• MIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/114352

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/114352