title: Hydrogen production by the unicellular, diazotrophic cyanobacterium Cyanothece sp. strain ATCC 51142 under conditions of continuous light.
abstract: We report on the hydrogen production properties of the unicellular, diazotrophic cyanobacterium Cyanothece sp. strain ATCC 51142. This organism has a versatile metabolism and can grow in the presence or absence of combined nitrogen and can grow photosynthetically or mixotrophically and heterotrophically in the presence of glycerol. The strain produces a bidirectional hydrogenase (encoded by the hox genes), an uptake hydrogenase (hupLS), and nitrogenase (nifHDK). We demonstrated hydrogen production by both the hydrogenase and the nitrogenase under appropriate metabolic conditions. The highest rates of hydrogen production were produced under nitrogen-fixing conditions when cells were grown and incubated under continuous light conditions, in either the presence or absence of glycerol. Under such nitrogen-fixing conditions, we have achieved rates of 300 micromol H(2)/mg chloramphenicol (Chl)/hr during the first 24 h of incubation. The levels of H(2) measured were dependent upon the incubation conditions, such as sparging with argon, which generated anaerobic conditions. We demonstrated that the same conditions led to high levels of H(2) production and N(2) fixation, indicating that low-oxygen conditions favor nitrogenase activity for both processes. The levels of hydrogen produced by the hydrogenase are much lower, typically 5 to 10 micromol H(2)/mg Chl/hr. Hydrogenase activity was dependent upon electron transport through photosystem II (PS II), whereas nitrogenase activity was more dependent on PS I, as well as on respiration. Although cells do not double under the incubation conditions when sparged with argon to provide a low-oxygen environment, the cells are metabolically active, and hydrogen production can be inhibited by the addition of chloramphenicol to inhibit protein synthesis.
authors.affiliation: Purdue University, Department of Biological Sciences, 201 S. University St., West Lafayette, IN 47907, USA.
authors.forename: Hongtao
authors.initials: H
authors.lastname: Min
authors.forename: Louis A
authors.initials: LA
authors.lastname: Sherman
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D046889:Cyanothece / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology; D005990:Glycerol / Q000378:metabolism; D006859:Hydrogen / Q000378:metabolism*; D006864:Hydrogenase / Q000235:genetics / Q000378:metabolism; D008027:Light; D009584:Nitrogen / Q000378:metabolism; D009586:Nitrogen Fixation; D009591:Nitrogenase / Q000235:genetics / Q000378:metabolism; D010788:Photosynthesis; D014176:Protein Biosynthesis
chemical_list: D001426:Bacterial Proteins; D006859:Hydrogen; D006864:Hydrogenase; D009591:Nitrogenase; D009584:Nitrogen; D005990:Glycerol
references.citation: Photosynth Res. 2006 May;88(2):109-17
references.pmid: 16453059
references.citation: Chem Rev. 2007 Oct;107(10):4206-72
references.pmid: 17927159
references.citation: Planta. 1985 Aug;165(3):430-8
references.pmid: 24241150
references.citation: Appl Microbiol Biotechnol. 2006 Sep;72(3):442-9
references.pmid: 16896600
references.citation: Appl Environ Microbiol. 1996 Apr;62(4):1220-6
references.pmid: 16535288
references.citation: Biochim Biophys Acta. 2001 Apr 2;1504(2-3):409-22
references.pmid: 11245804
references.citation: Appl Environ Microbiol. 2008 Oct;74(19):6102-13
references.pmid: 18676712
references.citation: J Bacteriol. 1998 Feb;180(3):519-26
references.pmid: 9457853
references.citation: J Bacteriol. 1993 Mar;175(5):1284-92
references.pmid: 8444791
references.citation: J Bacteriol. 2008 Jun;190(11):3904-13
references.pmid: 18390663
references.citation: Plant Physiol. 1997 Nov;115(3):991-1000
references.pmid: 12223855
references.citation: Appl Environ Microbiol. 1977 Nov;34(5):478-83
references.pmid: 412467
references.citation: J Bacteriol. 1997 Jul;179(13):4319-27
references.pmid: 9209050
references.citation: Biotechnol Bioeng. 2008 Aug 1;100(5):902-10
references.pmid: 18383143
references.citation: Proc Natl Acad Sci U S A. 2008 Sep 30;105(39):15094-9
references.pmid: 18812508
references.citation: J Phycol. 2009 Jun;45(3):610-20
references.pmid: 27034037
references.citation: Microbiol Mol Biol Rev. 2002 Mar;66(1):1-20, table of contents
references.pmid: 11875125
references.citation: Arch Microbiol. 1997 Feb-Mar;167(2-3):89-98
references.pmid: 9133330
references.citation: Plant Physiol. 1998 Apr;116(4):1551-62
references.pmid: 9536074
references.citation: J Bacteriol. 1994 Mar;176(6):1586-97
references.pmid: 8132452
references.citation: Proc Natl Acad Sci U S A. 2008 Apr 22;105(16):6156-61
references.pmid: 18427117
references.citation: Mol Biol Evol. 2008 Mar;25(3):536-48
references.pmid: 18093994
references.citation: Microb Cell Fact. 2005 Dec 21;4:36
references.pmid: 16371161
references.citation: J Bacteriol. 2004 Mar;186(6):1737-46
references.pmid: 14996805
references.citation: Crit Rev Microbiol. 2005;31(1):19-31
references.pmid: 15839402
references.citation: Chem Soc Rev. 2009 Jan;38(1):52-61
references.pmid: 19088964
references.citation: Planta. 2004 Jan;218(3):350-9
references.pmid: 14564521
references.citation: Biochim Biophys Acta. 2000 Sep 29;1468(1-2):150-60
references.pmid: 11018660
references.citation: Annu Rev Plant Biol. 2007;58:71-91
references.pmid: 17150028
references.citation: Photosynth Res. 2009 Mar;99(3):205-16
references.pmid: 19137411
references.citation: FEMS Microbiol Rev. 2007 Nov;31(6):692-720
references.pmid: 17903205
references.citation: Biochemistry. 2008 Dec 9;47(49):12939-41
references.pmid: 18998707
references.citation: Biochim Biophys Acta. 2007 Feb;1767(2):161-9
references.pmid: 17274945