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Appl Environ Microbiol. 2015 Jul;81(13):4507-16. doi: 10.1128/AEM.00679-15. Epub 2015 Apr 24.

Aerobic Hydrogen Production via Nitrogenase in Azotobacter vinelandii CA6.

Author information

1
Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, USA.
2
USDA ARS-NCSU, Raleigh, North Carolina, USA.
3
Department of Automatic and Systems Engineering, Polytechnic University of Valencia, Valencia, Spain.
4
Department of Biological Sciences, North Carolina State University, Raleigh, North Carolina, USA.
5
Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North Carolina, USA jbbarcen@ncsu.edu.

Abstract

The diazotroph Azotobacter vinelandii possesses three distinct nitrogenase isoenzymes, all of which produce molecular hydrogen as a by-product. In batch cultures, A. vinelandii strain CA6, a mutant of strain CA, displays multiple phenotypes distinct from its parent: tolerance to tungstate, impaired growth and molybdate transport, and increased hydrogen evolution. Determining and comparing the genomic sequences of strains CA and CA6 revealed a large deletion in CA6's genome, encompassing genes related to molybdate and iron transport and hydrogen reoxidation. A series of iron uptake analyses and chemostat culture experiments confirmed iron transport impairment and showed that the addition of fixed nitrogen (ammonia) resulted in cessation of hydrogen production. Additional chemostat experiments compared the hydrogen-producing parameters of different strains: in iron-sufficient, tungstate-free conditions, strain CA6's yields were identical to those of a strain lacking only a single hydrogenase gene. However, in the presence of tungstate, CA6 produced several times more hydrogen. A. vinelandii may hold promise for developing a novel strategy for production of hydrogen as an energy compound.

PMID:
25911479
PMCID:
PMC4475890
DOI:
10.1128/AEM.00679-15
[Indexed for MEDLINE]
Free PMC Article

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