Microbial biomarkers in Nasikie Engida, a hypersaline alkaline lake in southern Kenya
Abstract
The field of astrobiology utilizes proxy environments on Earth as a means of looking at environments in the search for life on other planets, as well as the origins of life on Earth. One aspect of this is looking in all ecosystems on earth, with a special focus on extreme environments, for clear, unequivocal signs of life. Biosignatures are these signs of life, both past and present, that include indicators such as organic molecules. The organic molecules, such as bacteriohopanepolyols (BHPs) and intact polar lipids (IPLs), are part of the membranes of bacterial and archaeal microbes, which are ubiquitous in marine and freshwater habitats worldwide. Such molecules can be found in sediments and provide us with knowledge of what organisms inhabited niches therein. Here we examine the microbial biomarkers in a lake sediment core from Nasikie Engida, Kenya. This hypersaline alkaline lake is a potential analog for exoplanets with saline aqueous environments such as those found on Mars, and is presently a sodium-carbonate lake precipitating nahcolite and trona. The focus is the distribution of microbial biomarkers found in the top ~100 cm of a core representing approximately 1,000 years of deposition. Shifts in biomarker distributions through the core are indicative of changes to the environment, primarily based on hydrological budgets, and the resulting shifts in microbial communities inhabiting this evaporative basin. Understanding the relationships between microbial communities, their biomarkers, and environmental conditions is key to reconstructing ancient systems, as well as extrapolating to exoplanetary systems.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B53E2449C
- Keywords:
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- 0424 Biosignatures and proxies;
- BIOGEOSCIENCES;
- 0473 Paleoclimatology and paleoceanography;
- BIOGEOSCIENCES;
- 4912 Biogeochemical cycles;
- processes;
- and modeling;
- PALEOCEANOGRAPHY;
- 4924 Geochemical tracers;
- PALEOCEANOGRAPHY