Implementation of uranium bioremediation requires methods for monitoring the 
membership and activities of the subsurface microbial communities that are 
responsible for reduction of soluble U(VI) to insoluble U(IV). Here, we report a 
proteomics-based approach for simultaneously documenting the strain membership 
and microbial physiology of the dominant Geobacter community members during in 
situ acetate amendment of the U-contaminated Rifle, CO, aquifer. Three 
planktonic Geobacter-dominated samples were obtained from two wells 
down-gradient of acetate addition. Over 2,500 proteins from each of these 
samples were identified by matching liquid chromatography-tandem mass 
spectrometry spectra to peptides predicted from seven isolate Geobacter genomes. 
Genome-specific peptides indicate early proliferation of multiple M21 and 
Geobacter bemidjiensis-like strains and later possible emergence of M21 and G. 
bemidjiensis-like strains more closely related to Geobacter lovleyi. Throughout 
biostimulation, the proteome is dominated by enzymes that convert acetate to 
acetyl-coenzyme A and pyruvate for central metabolism, while abundant peptides 
matching tricarboxylic acid cycle proteins and ATP synthase subunits were also 
detected, indicating the importance of energy generation during the period of 
rapid growth following the start of biostimulation. Evolving Geobacter strain 
composition may be linked to changes in protein abundance over the course of 
biostimulation and may reflect changes in metabolic functioning. Thus, 
metagenomics-independent community proteogenomics can be used to diagnose the 
status of the subsurface consortia upon which remediation biotechnology relies.