The Gene and Linda Voiland School of Chemical Engineering and Bioengineering department at Washington State University is pleased to invite you to our upcoming seminar Monday, November 9, at 12:10 p.m. in Todd 311.
Steve Lindemann completed his bachelor’s degree at Purdue University and his Ph.D. work at the University of Iowa. He went on to post-doctoral training with Jim Fredrickson at Pacific Northwest National Lab studying interspecies interactions in microbial communities, where he now is on staff as a senior research scientist focusing on linkages between carbon and nitrogen cycles in microbial communities.
Division of labor in microbial communities: perspectives from phototrophic mats and consortial biofilms
Phototrophic microbial mats are communities in which the activities of disparate members generate sharp physicochemical gradients that, in turn, impose spatial structure where metabolic functions are localized. In these communities, entire biogeochemical cycles can take place within a millimeters-thick structure of interacting microbes, which each perform key biotransformations. As such, microbial mats are excellent model systems in which to study microbial interactions that permit division of metabolic labor. One required community function is
acquisition of the nitrogen required for growth. In phototrophic consortia derived from the Hot Lake microbial mat, acquisition of nitrate is functionally compartmentalized by species whereas acquisition of ammonium is not. Despite the increased energetic cost of nitrate reduction over ammonium assimilation, phototrophic biofilms grown in nitrate displayed increased net biomass productivity and stability despite smaller cell biovolume compared with biofilms grown in ammonium. Stable isotope probing linked with proteomics and nanoSIMS revealed that when nitrate is the sole nitrogen source, carbon is quickly shared with heterotrophs as photosynthate where heterotrophs consume polymeric carbon when ammonium is present. This suggests that increased biomass productivity from metabolic division of labor arises from accumulation of exopolymeric
carbon (likely polysaccharides) rather than cell biomass and that these polymers accumulate due to imbalance in the rates of community nitrogen and carbon acquisition.
