Binder, B. J. Dept. Marine Sciences, University of Georgia, bbinder@arches.uga.edu
Liu, Y. Dept. Marine Sciences, University of Georgia, ycliu@arches.uga.edu

 
INFLUENCE OF DIFFERENT GROWTH-LIMITING FACTORS ON THE RELATIONSHIP BETWEEN MACROMOLECULAR COMPOSITION AND GROWTH RATE IN A MARINE SYNECHOCOCCUS SPP.
 
The strong correlation between macromolecular composition and growth rate in E. coli and other well-studied prokaryotes supports the suggestion that cellular composition might be used to assess in situ growth rates of natural microbial populations. Successful application of this approach requires knowledge of the relationships between macromolecular composition and growth rate in the organisms of interest, and of the influence of environmental factors on these relationships. We have previously reported on growth rate-regulated changes in macromolecular composition of single cells of marine Synechococcus WH8101 growing under light-limitation. Here we extend those results to include nutrient-limited growth. DNA and cell biomass varied with growth rate in approximately the same manner under N-limitation as under light-limitation, although at the highest growth rates, N-limited cells were slightly smaller and had slightly less DNA than did light-limited cells. In contrast, at all growth rates examined N-limitation resulted in significantly less cellular rRNA as compared with light-limitation. These observations suggest that notwithstanding the widely accepted (E. coli-based) prokaryotic model, the relationship between macromolecular composition and growth rate in marine Synechococcus can be influenced by the nature of the growth-limiting factor. Composition-based estimates of in situ growth rate must take into account this influence.
 
Day: Tuesday, Feb. 2
Time:
Location: Sweeney Center
 
Code: SS41TU0470S