• Roth, John R (PI)

Project: Research project

Project Details


Vitamin B12 is an essential nutrient for humans, that is only synthesized
by microbes. Little is known about its biosynthesis or its physiological
importance to the microbes that produce it. The bacterium Salmonella
typhimurium is capable of a complete synthesis of B12, but does so only
under anaerobic conditions. Since sophisticated genetics can be done in
this bacterium, we propose a genetic approach to understanding the
biosynthesis of vitamin B12 in this organism. We will identify the genes
involved (probably an excess of thirty) and will pursue how this pathway is
regulated with special emphasis on how 02 is involved. The genetic and biochemical study of enteric bacteria has been done largely
under aerobic conditions. Relatively little is known about the details of
the anaerobic life-style of these organisms even though virtually all their
interactions with human hosts (colonization and pathogenesis) proceed in
the absence of oxygen. We suspect that production of B12 anaerobically
indicates the existence of a substantial body of metabolic activity that
occurs only anaerobically and is totally unknown. We propose to approach
these aspects of metabolism by studying the role of B12 in the anaerobic
life of Salmonella.
Effective start/end date7/1/858/31/05


  • National Institutes of Health: $315,850.00
  • National Institutes of Health: $78,224.00
  • National Institutes of Health: $398,121.00
  • National Institutes of Health: $385,084.00
  • National Institutes of Health: $105,283.00


  • Medicine(all)
  • Biochemistry, Genetics and Molecular Biology(all)


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