Marina Resendes de Sousa António
Graduate Student

E-mail

The main goal of my research is to characterize the microbial diversity and abundance present in Anderson Lake situated in Warner Valley, Oregon. The estimated age of Warner Valley is about 50 million years old, approximately the last glacial age. This lake in particular is a shallow environment (mud flat, 15-30cm of water in summer season that can reach a maximum of 1-2m in winter season). Available data indicate that this is an alkaline (8.8-9.2 pH) brackish/saline environment with high levels of arsenic (700-10070ppm). The high levels of arsenic are thought to derive from an arsenic mountain on the bottom of which the lake is located.

The peculiarities of this lake are of scientific interest because it is thought that it might mimic how early Earth and Mars could have looked like. An environment that never dried completely, but that did not have large amounts of water as is the case of larger lakes, rivers or oceans could very likely be prone to early life. Low water levels allow the concentration of nutrients, minerals and organic molecules, increasing the interaction chances between them. It is worth to mention that this environment was never studied before, and biodiversity present in it was hardly imaginable.

As a first approach to estimate biodiversity in Anderson Lake, a single sample collected at the offshore of the lake was analyzed through 16S rDNA approach. Over a 1,000 sequences (1,224) were analyzed in order to obtain a redundancy level of 70%. This number by itself represents an extremely high diversity, to which the finding of representatives from a large number of phyla is added. Out of these 1,224 sequences, 226 (18%) have =<95% similarity to their closest relative. Phylogenetic preliminary studies point out to the finding of new species, genus, family/order and even phylum candidates.

Further effort needs to be made in order to understand the biological complexity and uniqueness of this environment. Future approaches include a systematic sample collection across the lake and eventually in depth sampling, coupled to seasonal sampling. Abundance quantification, 16S rDNA classification and attempts to isolation and culture of typical and abundant microorganisms aside with specific probes to target particular microorganisms of interest as phylum candidates are desired.