EXAMINING THE RESPONSE OF WIDESPREAD SEDIMENT ASSOCIATED CABLE BACTERIA ACTIVITY TO A LABORATORY MANIPULATION

Cable bacteria are long filamentous sediment-associated microbes, found in marine and freshwater environments, capable of electron transport along their filaments from sulfide to oxygen. Their activity is often responsible for a majority of the oxygen consumption and sulfide depletion in sediments. Cable bacteria have an important role in biogeochemical cycles and have the potential to abate toxicity of pollutants in the environment. Cable bacteria serve as electron acceptors where oxygen is not available, potentially stimulating the activity of other beneficial microbes in the sediment environment. To test how cable bacteria interact with other bacteria in sediments, we need a means to interrupt their activity. A previous experiment suggested there may be enhanced activity of cable bacteria following an experimental cutting treatment. Over time, cable bacteria are able to re-orient their position to 'plug' back into oxygen. The objective of this study was to test if the activity of cable bacteria is stimulated by cutting their access from oxygen. My approach was to conduct a time series incubation experiment. In a container, I mixed the upper 20 cm of the sediment cores collected from the main channel in the Chesapeake Bay with artificial sea water; this was then sealed to asphyxiate and subsequently remove macrofauna. Then, I incubated the sediment in core liners with pre-cut slits and hose clamps, pushed up by a few millimeters with a silicone stopper, under oxygenated conditions in aquaria, to stimulate the growth of cable bacteria. Once cable bacteria were growing, in a subset of experimental sediment cores, I performed a 'cutting treatment' by passing a fishing line horizontally through the sediments. I then continued to follow the activity of cable bacteria over time in the intact sediments and in the 'cut treatment' sediments. The activity of cable bacteria was tracked using microsensor profiling. My hypothesis was that the cutting treatment would enhance the activity of cable bacteria, by driving the filaments to reconnect with oxygen. Here, using pH and electric potential microsensors, I assessed the activity of cable bacteria before and after manipulating the sediment to directly observe if cable bacteria activity may be stimulated by a cutting treatment. In this contribution I will discuss how various manipulations impacted the activity of cable bacteria.

Presentation Preference: Poster

Primary Presenter: Liz Collazo, University of Puerto Rico at Humacao (lizcoll04@gmail.com)

Authors:

Liz Collazo Pagán, University of Puerto Rico at Humacao  (liz.collazo1@upr.edu)

Carol Kim, Horn Point Laboratory, University of Maryland Center for Environmental Science  (ckim@umces.edu)

Sairah Malkin, Horn Point Laboratory, University of Maryland Center for Environmental Science  (smalkin@umces.edu)