The Richard Hay Lecture

High-temperature Chemotrophic Environments are Excellent
Model Systems for Understanding Microbial Controls

on Geochemical Cycling

Dr. Bill Inskeep
Montana State University

 

Abstract

Geothermal systems in Yellowstone National Park (YNP) are geochemically diverse, span pH values from approximately 2 to 10, and generally contain a plethora of reduced constituents that may serve as electron donors for chemotrophic microorganisms. One of our long-term goals has been to determine linkages between geochemical processes and the distribution and physiology of microbial populations in high-temperature environments, where geochemical conditions often constrain microbial community diversity. Although geochemical characteristics vary greatly across YNP, there exist key geochemical attributes that are likely most important for defining patterns in microbial distribution. Numerous geothermal systems in YNP are dominated by geochemical processes involving S, As, and or Fe. In such cases, we hypothesize that genetic diversity and functional gene content will link directly with habitat parameters. Several cases studies will be presented where pilot metagenomic data (random shotgun sequencing of environmental DNA) was used to identify key functional attributes and confirm that specific patterns of microbial distribution are indeed highly correlated with geochemical conditions. These highly-constrained environments are excellent systems for elucidating definitive linkages among S, As, and or Fe cycling, genomics and microbial regulation.