Kaplan, L. A. Stroud Water Research Center, lakaplan@stroudcenter.org

 
DISSOLVED ORGANIC MATTER METABOLISM AS A LINK TO HETEROGENEITY IN COMMUNITIES OF HETEROTROPHIC BACTERIA
 
Two central questions in aquatic sciences are: (1) what determines whether an organic molecule or compound is biodegradable, and (2) how cosmopolitan are the various species of microbiota? If different environments contain the same resource of available species then a reasonable hypothesis is that comparable community structure will develop in habitats when exposed to similar chemical and physical environments. Studies with biofilm communities from streams in diverse biomes showed that each community was able to metabolize 10 to 30% of the DOC present in the streamwater from which it was colonized. However, short-term (hours) and long-term (weeks) cross-feeding experiments with biofilms from one biome and DOC sources from another revealed an inability to metabolize the DOC. I suggest that community acclimation to "foreign" DOC sources occurs through a replacement of species rather than selection from within the indigenous microflora. I will describe the temporal and spatial dynamics of DOC within a stream ecosystem, and couple this with reports of bacterial community composition from different aquatic habitats to present a heuristic model of how DOC heterogenitiy and physical mixing can generate differences in bacterial community composition in habitats ranging from small streams to the open oceans.
 
Day: Thursday, Feb. 4
Time: 09:45 - 10:00am
Location: Sweeney Center
 
Code: SS33TH0945S