title: Biohydrogen production by purple non-sulfur bacteria Rhodobacter sphaeroides: Effect of low-intensity electromagnetic irradiation.
abstract: The present work was focused on the effects of low-intensity (the flux capacity was of 0.06mWcm(-2)) electromagnetic irradiation (EMI) of extremely high frequencies or millimeter waves on the growth and hydrogen (H2) photoproduction by purple non-sulfur bacteria Rhodobacter sphaeroides MDC6521 (from Armenian mineral springs). After exposure of R. sphaeroides, grown under anaerobic conditions upon illumination, to EMI (51.8GHz and 53.0GHz) for 15min an increase of specific growth rate by ~1.2-fold, in comparison with control (non-irradiated cells), was obtained. However, the effect of EMI depends on the duration of irradiation: the exposure elongation up to 60min caused the delay of the growth lag phase and the decrease specific growth rate by ~1.3-fold, indicating the bactericidal effect of EMI. H2 yield of the culture, irradiated by EMI for 15min, determined during 72h growth, was ~1.2-fold higher than H2 yield of control cells, whereas H2 production by cultures, irradiated by EMI for 60min was not observed during 72h growth. This difference in the effects of extremely high frequency EMI indicates a direct effect of radiation on the membrane transfer and the enzymes of these bacteria. Moreover, EMI increased DCCD-inhibited H(+) fluxes across the bacterial membrane and DCCD-sensitive ATPase activity of membrane vesicles, indicating that the proton FoF1-ATPase is presumably a basic target for extremely high frequency EMI related to H2 production by cultures.
authors.affiliation: Department of Biochemistry, Microbiology and Biotechnology, Yerevan State University, 1 A. Manoukian Str., 0025 Yerevan, Armenia; Research Institute of Biology, Yerevan State University, 1 A. Manoukian Str., 0025 Yerevan, Armenia.
authors.forename: Lilit
authors.initials: L
authors.lastname: Gabrielyan
authors.affiliation: Research Institute of Biology, Yerevan State University, 1 A. Manoukian Str., 0025 Yerevan, Armenia.
authors.forename: Harutyun
authors.initials: H
authors.lastname: Sargsyan
authors.affiliation: Department of Biochemistry, Microbiology and Biotechnology, Yerevan State University, 1 A. Manoukian Str., 0025 Yerevan, Armenia; Research Institute of Biology, Yerevan State University, 1 A. Manoukian Str., 0025 Yerevan, Armenia. Electronic address: Trchounian@ysu.am.
authors.forename: Armen
authors.initials: A
authors.lastname: Trchounian
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D060733:Electromagnetic Radiation; D006859:Hydrogen / Q000378:metabolism*; D010084:Oxidation-Reduction; D006180:Proton-Translocating ATPases / Q000378:metabolism; D012242:Rhodobacter sphaeroides / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects
chemical_list: D001426:Bacterial Proteins; D006859:Hydrogen; D006180:Proton-Translocating ATPases
keywords: Electromagnetic irradiation; F(o)F(1)-ATPase; H(+) flux; H(2) production; Photofermentation; Rhodobacter sphaeroides