THE INFLUENCE OF ENVIRONMENTAL DISTURBANCE ON PHYCOSPHERE-ASSOCIATED BACTERIA FROM ANTARCTIC LAKES

The phycosphere is the interface for complex networks of interactions between algae and their bacterial partners. These interactions primarily involve the exchange of metabolites. Algae commonly share fixed organic carbon in the form of small metabolites with their bacterial counterparts, often in exchange for compounds benefiting algal growth (e.g. phytohormones, vitamins, micronutrients). The phycosphere is also a site of negative interactions: for example, production of algicidal or antibacterial compounds under nutrient limiting conditions. Lakes within the McMurdo Dry Valleys (MDV), Antarctica, represent some of the last perennially ice-covered lakes on the planet. Algae-bacteria interactions within the water column of the MDV lakes are of high interest: the food web is entirely microbial and fixed carbon is almost entirely autochthonous. The lack of external inputs into these lakes places a greater importance on the photosynthetic algae within them as major organic carbon producers. In this project, we first developed cultures from East Lake Bonney and Lake Fryxell using defined autotrophic growth media to enrich algae-bacteria interactions. Then we tested the impact of nutrient deprivation on the stability of algae-bacteria interactions using size fractionation filtration followed by 16S and 18S rRNA sequencing. Our preliminary findings indicate that while there are specific bacterial taxa associated with MDV phytoplankton, MDV algae-bacteria interactions are not significantly impacted by nutrient status.

Primary Presenter: Bradley Krzysiak, Miami University (krzysibm@miamioh.edu)

Authors:

Bradley Krzysiak, Miami University  (krzysibm@miamioh.edu)

Rachael Morgan-Kiss, Miami University  (morganr2@miamioh.edu)