- 著者
- Tetsuya YAMADA Satoshi KAWAICHI Akihisa MATSUYAMA Minoru YOSHIDA Nobuhiro MATSUSHITA Ryuhei NAKAMURA
- 出版者
- 公益社団法人 電気化学会
- 雑誌
- Electrochemistry (ISSN:13443542)
- 巻号頁・発行日
- vol.84, no.5, pp.312-314, 2016-05-05 (Released:2016-05-05)
- 参考文献数
- 19
- 被引用文献数
- 3
The present study investigated extracellular electron transfer (EET) of Pseudomonas stutzeri, a model organism for bacterial denitrification. Electrochemical cultivation of P. stutzeri in a lithotrophic medium with Fe2+ ions generated the clear cathodic current associated with denitrification reactions. The EET ability of P. stutzeri was greatly strengthened by the addition of acetate, which correlated with the enhanced rate of the enzymatic oxidation of Fe2+. Since the addition of acetate induced the change of cellular metabolisms from lithotrophic denitrification to mixotrophic one, the present finding suggests the effectiveness of EET monitoring as a descriptor of bacterial denitrification activity and changing metabolisms according to the environmental conditions.
- 著者
- Luo PENG Xiao-Ting ZHANG Satoshi KAWAICHI De-Ti XIE Zhen-Lun LI
- 出版者
- 公益社団法人 電気化学会
- 雑誌
- Electrochemistry (ISSN:13443542)
- 巻号頁・発行日
- vol.83, no.8, pp.600-604, 2015-08-05 (Released:2015-08-05)
- 参考文献数
- 28
- 被引用文献数
- 2
In bioelectrochemical systems where the oxidative current is mediated by microorganisms, it remains unexplored as to whether low-potential substrates (e.g. formate) enable the anode to work at lower potentials. Due to implications to relevant engineering and natural systems, this study evaluated such possibility and underlying causes. The investigation compared voltammograms of the model exoelectrogen (to exclude the interfering factors in undefined cultures) Geobacter sulfurreducens grown with acetate and formate. G. sulfurreducens had an EM (half-saturation potential) of −0.138 ± 0.004 V vs. SHE when consuming acetate; an EM of −0.160 ± 0.002 V when utilizing formate. Such variation usually requires alternation in electrode reductase expressed by bacteria, according to the existing Nernst-Monod model with a single species of electron conduit. For both acetate- and formate-grown biofilm, non-catalytic voltammetries found multiple redox couples with distinct formal potentials. No clear evidence could support a hypothesis that the bacteria synthesized any different electron conduits when the substrate was changed. Significant changes in the relative abundance of high-potential and low-potential electrocatalytically active conduits were not observed as well. However, low-potential conduits showed elevated electrocatalytic activities in the formate-grown biofilm, which might induce the shift in apparent EM.
- 著者
- Satoshi Kawaichi Norihiro Ito Takashi Yoshida Yoshihiko Sako
- 出版者
- 日本微生物生態学会 / 日本土壌微生物学会 / Taiwan Society of Microbial Ecology / 植物微生物研究会
- 雑誌
- Microbes and Environments (ISSN:13426311)
- 巻号頁・発行日
- pp.ME13048, (Released:2013-11-21)
- 被引用文献数
- 3 9
Physicochemical characteristics and archaeal and bacterial community structures in an iron-rich coastal hydrothermal field, where the temperature of the most active hot spot reaches above 100ーC, were investigated to obtain fundamental information on microbes inhabiting a coastal hydrothermal field. The environmental settings of the coastal hydrothermal field were similar in some degree to those of deep-sea hydrothermal environments because of its emission of H2, CO2, and sulfide from the bottom of the hot spot. The results of clone analyses based on the 16S rRNA gene led us to speculate the presence of a chemo-synthetic microbial ecosystem, where chemolithoautotrophic thermophiles, primarily the bacterial order Aquificales, function as primary producers using H2 or sulfur compounds as their energy source and CO2 as their carbon source, and the organic compounds synthesized by them support the growth of chemoheterotrophic thermophiles, such as members of the order Thermales and the family Desulfurococcaceae. In addition, the dominance of members of the bacterial genus Herbaspirillum in the high temperature bottom layer led us to speculate the temporal formation of mesophilic zones where they can also function as primary producing or nitrogen-fixing bacteria.