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Title: N 2 gas is an effective fertilizer for bioethanol production by Zymomonas mobilis

A nascent cellulosic ethanol industry is struggling to become cost-competitive against corn ethanol and gasoline. Millions of dollars are spent on nitrogen supplements to make up for the low nitrogen content of the cellulosic feedstock. In this paper, we show for the first time to our knowledge that the ethanol-producing bacterium, Zymomonas mobilis, can use N 2 gas in lieu of traditional nitrogen supplements. Despite being an electron-intensive process, N 2 fixation by Z. mobilis did not divert electrons away from ethanol production, as the ethanol yield was greater than 97% of the theoretical maximum. In a defined medium, Z. mobilis produced ethanol 50% faster per cell and generated half the unwanted biomass when supplied N 2 instead of ammonium. In a cellulosic feedstock-derived medium, Z. mobilis achieved a similar cell density and a slightly higher ethanol yield when supplied N 2 instead of the industrial nitrogen supplement, corn steep liquor. Finally, we estimate that N 2-utilizing Z. mobilis could save a cellulosic ethanol production facility more than $1 million/y.
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  1. Indiana Univ., Bloomington, IN (United States)
Publication Date:
Grant/Contract Number:
Published Article
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 112; Journal Issue: 7; Journal ID: ISSN 0027-8424
National Academy of Sciences, Washington, DC (United States)
Research Org:
Indiana Univ., Bloomington, IN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
Country of Publication:
United States
59 BASIC BIOLOGICAL SCIENCES; 09 BIOMASS FUELS; Zymomonas mobilis; nitrogenase; ethanol; cellulosic; biofuel
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1348418