Microarray analysis of the effects of heat and cold stress on hydrogen production metabolism of Rhodobacter capsulatus

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2011
Gürgan Doğan, Muazzez
Rhodobacter capsulatus DSM1710 is a purple non-sulfur bacterium capable of hydrogen production via photofermentation. Biohydrogen is a clean and renewable way of hydrogen production, which can be achieved by PNS bacteria in outdoor large scale photobioreactors using sun light. In outdoor conditions bacteria can be exposed to heat and cold stress. In this study in order to understand the effects of heat and cold stress on photofermentative hydrogen production and gene expression profile of R.capsulatus on acetate as the carbon source, microarray analysis was carried out. Since there is no commercially available microarray chip for R.capsulatus, an Affymetrix GeneChip® was designed and it was manufactured by Affymetrix.The experiments were conducted at 30 ⁰C as the control condition, 42 ⁰C for heat stress and 4 ⁰C for cold stress under constant illumination of 2000 lux. Growth of bacteria, pH of the media, hydrogen production and acetate consumption weredetermined periodically. Upon heat and cold stress hydrogen production was stopped, while bacterial growth continued under cold stress but stopped under heat stress. Acetate could be utilized totally under cold stress, however, some acetate remained in the medium after heat stress application. Microarray analysis revealed that genes taking role in nitrogen metabolism, photosynthesis and electron transport, which are core metabolisms for hydrogen production were highly up regulated under cold stress, while down regulated under heat stress, meaning that heat stress inhibited hydrogen and energy production of R.capsulatus. Moreover, cell envelope and related transporter and binding proteins were negatively affected by heat stress.

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Citation Formats
M. Gürgan Doğan, “Microarray analysis of the effects of heat and cold stress on hydrogen production metabolism of Rhodobacter capsulatus,” M.S. - Master of Science, Middle East Technical University, 2011.