Improvement of biohydrogen production by genetic manipulations in rhodobacter sphaeroides O.U.001

Kars, Gökhan
Rhodobacter sphaeroides O.U.001 is a purple non-sulphur bacterium producing hydrogen under photoheterotrophic, nitrogen limited conditions. Hydrogen is produced by Mo-nitrogenase but substantial amount of H2 is reoxidized by a membrane bound uptake hydrogenase. In this study, hydrogen production and the expression of structural nitrogenase genes were investigated by varying molybdenum and iron ion concentrations. These two elements are found in the structure of Mo-nitrogenase and they are important for functioning of the enzyme. The results showed that hydrogen production and nifD gene expression increased upon increase in molybdenum concentration. Increasing iron concentration had also positive effect on hydrogen production and nifK gene expression. To improve the hydrogen producing capacity of R. sphaeroides O.U.001, hupSL genes encoding uptake hydrogenase were disrupted in two different methods. In the first method, hup genes were disrupted by gentamicin resistance gene insertion. In the second method, part of the hup gene was deleted without using antibiotic resistance gene. The wild type and the hup- mutant cells showed similar growth patterns but substantially more hydrogen was produced by the mutant cells. The genes coding for hox1 hydrogenase of Thiocapsa roseopersicina was aimed to be expressed in R. sphaeroides O.U.001 to produce H2 under nitrogenase repressed and mixotrophic conditions. The hox1 hydrogenase genes of T. roseopersicina were cloned and transferred to R. sphaeroides. Although the cloning was successful, the expression of hydrogenase was not achieved by using either the native promoter of hox1 hydrogenase or the crtD promoter of T. roseopersicina.


Kinetic analyses of the effects of temperature and light intensity on growth, hydrogenm production and organic acid utilization by rhodobacter capsulatus
Sevinç, Pelin; Gündüz, Ufuk; Department of Biotechnology (2010)
Effects of temperature and light intensity on photofermentative hydrogen production by Rhodobacter capsulatus DSM1710 by use of acetic and lactic acids as substrates were studied. Experiments were conducted at 20, 30 and 38oC incubator temperatures under light intensities in the 1500 – 7000 lux range. pH of the medium and quantity of hydrogen forming together with quantity of biomass, and concentrations of acetic, lactic, formic, butyric and propionic acids in the medium were determined periodically. Growth...
Evaluation of hydrogen production by Rhodobacter sphaeroides OU001 and its hupSL deficient mutant using acetate and malate as carbon sources
KARS, GÖKHAN; Gündüz, Ufuk; Yucel, Meral; Rakhely, Gabor; Kovacs, Kornel L.; Eroglu, Inci (2009-03-01)
Rhodobacter sphaeroides O.U.001 is one of the candidates for photobiological hydrogen production among purple non-sulfur bacteria. Hydrogen is produced by Mo-nitrogenase from organic acids such as malate or lactate. A hupSL in frame deletion mutant strain was constructed without using any antibiotic resistance gene. The hydrogen production potential of the R. sphaeroides O.U.001 and its newly constructed hupSL deleted mutant strain in acetate media was evaluated and compared with malate containing media. Th...
Kinetic analysis of photosynthetic growth, hydrogen production and dual substrate utilization by Rhodobacter capsulatus
Sevinc, Pelin; Gündüz, Ufuk; EROĞLU, İNCİ; Yucel, Meral (2012-11-01)
Rhodobacter capsulatus is purple non-sulfur (PNS) bacterium which can produce hydrogen and CO2 by utilizing volatile organic acids in presence of light under anaerobic conditions. Photofermentation by PNS bacteria is strongly affected by temperature and light intensity. In the present study we present the kinetic analysis of growth, hydrogen production, and dual consumption of acetic acid and lactic acid at different temperatures (20, 30 and 38 degrees C) and light intensities (1500, 2000, 3000, 4000 and 50...
Effect of light intensity, wavelength and illumination protocol on hydrogen production in photobioreactors
Uyar, Basar; EROĞLU, İNCİ; Yucel, Meral; Gündüz, Ufuk; Turker, Lemi (2007-12-01)
Rhodobacter sphaeroides O.U. 001 is a purple non-sulfur bacterium which evolves hydrogen from the breakdown of organic acids under illumination and anaerobic conditions. In this study, the effect of light intensity, light wavelength and illumination protocol on the growth and hydrogen production of R. sphaeroides O.U. 001 was investigated in gas-tight glass photobioreactors with defined medium. The results showed Also it was found that the rate of hydrogen production increased with increasing light intensit...
Cloning and heterologous expression of chlorophyll a synthase in Rhodobacter sphaeroides
Ipekoglu, Emre M.; Gocmen, Koray; Oz, Mehmet T.; Gurgan, Muazzez; Yucel, Meral (2017-03-01)
Rhodobacter sphaeroides is a purple non-sulfur bacterium which photoheterotrophically produces hydrogen from organic acids under anaerobic conditions. A gene coding for putative chlorophyll a synthase (chlG) from cyanobacterium Prochlorococcus marinus was amplified by nested polymerase chain reaction and cloned into an inducible-expression plasmid which was subsequently transferred to R. sphaeroides for heterologous expression. Induced expression of chlG in R. sphaeroides led to changes in light absorption ...
Citation Formats
G. Kars, “Improvement of biohydrogen production by genetic manipulations in rhodobacter sphaeroides O.U.001,” Ph.D. - Doctoral Program, Middle East Technical University, 2008.