Thermal Biology Institute Seminar Series
- Monday, February 9, 2015 from 3:10pm to 4:00pm
- Plant Biosciences Building - view map
Please join the Thermal Biology Institute for our seminar on Monday, February 9th. Jake Beam, MSU Ph.D. candidate from the Bill Inskeep lab will present, "Assembly and Succession of Iron Oxide Microbial Mat Communities in Acidic Geothermal Springs" at 3:10pm in 108 Plant Bioscience Building.
Abstract: Iron oxide microbial mats are ubiquitous geobiological features on Earth and occur in extant acidic hot springs of Yellowstone National Park (YNP), WY, USA. Iron oxide mats in acidic geothermal springs form as a result of microbial processes, and the relative contribution of different organisms to the development of these mat ecosystems is of specific interest. We hypothesized that chemolithoautotrophic organisms contribute to the early development and production of Fe(III)-oxide mats, which could support later-colonizing heterotrophic microorganisms. Sterile glass slides were incubated in the outflow channels of two acidic geothermal springs in YNP, and spatiotemporal changes in Fe(III)-oxide accretion and abundance of relevant community members were measured. Lithoautotrophic Hydrogenobaculum spp. populations were early colonizers of glass surfaces and the most abundant taxa identified at early successional stages (< 7 days). Populations of M. yellowstonensis colonize after ~ 7 days, corresponding to visible Fe(III)-oxide accretion. Heterotrophic archaea colonize after 30 days of slide incubation and become the dominant populations in mature iron oxide mats (i.e., > 1 cm thick) that form after 70 - 100 days. First-order rate constants of iron oxide accretion (1.1 - 1.2 hr-1) were similar at two sites, but differences reflect the absolute amount of iron accreted. Micro- and macroscale microterracettes were identified during iron oxide mat development and suggest that a mass transfer boundary layer may limit oxygen diffusion. A steep gradient in oxygen consumption occurs at the aqueous-mat interface of ~ 1 mm, and indicate that O2 is diffusion-limited in these systems. The formation and succession of amorphous Fe(III)-oxide mat communities follows a predictable pattern of distinct stages and growth. The successional stages observed in these Fe(III)-oxide mat communities are relevant to other iron oxide mineralizing systems, and the biogeochemical and morphological signatures of these extant mats may be important for interpreting ancient iron oxide mineral deposits.
- Thermal Biology Institute