{"id":13462,"date":"2019-03-01T14:28:46","date_gmt":"2019-03-01T22:28:46","guid":{"rendered":"https:\/\/www.darkenergybiosphere.org\/?post_type=publication&#038;p=13462"},"modified":"2019-03-15T13:13:46","modified_gmt":"2019-03-15T20:13:46","slug":"growth-kinetics-carbon-isotope-fractionation-and-gene-expression-in-the-hyperthermophile-methanocaldococcus-jannaschii-during-hydrogen-limited-growth-and-interspecies-hydrogen-transfer","status":"publish","type":"publication","link":"https:\/\/www.darkenergybiosphere.org\/publication\/growth-kinetics-carbon-isotope-fractionation-and-gene-expression-in-the-hyperthermophile-methanocaldococcus-jannaschii-during-hydrogen-limited-growth-and-interspecies-hydrogen-transfer\/","title":{"rendered":"Growth Kinetics, Carbon Isotope Fractionation, and Gene Expression in the Hyperthermophile Methanocaldococcus jannaschii during Hydrogen-Limited Growth and Interspecies Hydrogen Transfer"},"content":{"rendered":"<p>Hyperthermophilic methanogens are often H<sub>2<\/sub>\u00a0limited in hot subseafloor environments and their survival may be due in part to physiological adaptations to low H<sub>2<\/sub>\u00a0conditions and interspecies H<sub>2<\/sub>\u00a0transfer. The hyperthermophilic methanogen\u00a0<em>Methanocaldococcus jannaschii<\/em>\u00a0was grown in monoculture at high (80-83 \u03bcM) and low (15-27 \u03bcM) aqueous H<sub>2<\/sub>\u00a0concentrations and in co-culture with the hyperthermophilic H<sub>2<\/sub>\u00a0producer\u00a0<em>Thermococcus paralvinellae<\/em>. The purpose was to measure changes in growth and CH<sub>4<\/sub>\u00a0production kinetics, CH<sub>4<\/sub>\u00a0fractionation, and gene expression in\u00a0<em>M. jannaschii<\/em>\u00a0with changes in H<sub>2<\/sub>\u00a0flux. Growth and cell-specific CH<sub>4<\/sub>\u00a0production rates of\u00a0<em>M. jannaschii<\/em>\u00a0decreased with decreasing H<sub>2<\/sub>\u00a0availability and decreased further in co-culture. However, cell yield (cells produced per mole of CH<sub>4<\/sub>\u00a0produced) increased six-fold when\u00a0<em>M. jannaschii<\/em>\u00a0was grown in co-culture relative to monoculture. Relative to high H<sub>2<\/sub>concentrations, isotopic fractionation of CO<sub>2<\/sub>\u00a0to CH<sub>4<\/sub>\u00a0(\u03f5<sub>CO2-CH4<\/sub>) was 16\u2030 larger for cultures grown at low H<sub>2<\/sub>\u00a0concentrations and 45\u2030 and 56\u2030 larger for\u00a0<em>M. jannaschii<\/em>\u00a0growth in co-culture on maltose and formate, respectively. Gene expression analyses showed H<sub>2<\/sub>-dependent methylene-tetrahydromethanopterin (H<sub>4<\/sub>MPT) dehydrogenase expression decreased and coenzyme F<sub>420<\/sub>-dependent methylene-H<sub>4<\/sub>MPT dehydrogenase expression increased with decreasing H<sub>2<\/sub>\u00a0availability and in co-culture growth. In co-culture, gene expression decreased for membrane-bound ATP synthase and hydrogenase. The results suggest that H<sub>2<\/sub>\u00a0availability significantly affects the CH<sub>4<\/sub>\u00a0and biomass production and CH<sub>4<\/sub>\u00a0fractionation by hyperthermophilic methanogens in their native habitats.<\/p>\n","protected":false},"template":"","tags":[],"publication_type":[19],"_links":{"self":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/publication\/13462"}],"collection":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/publication"}],"about":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/types\/publication"}],"wp:attachment":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/media?parent=13462"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/tags?post=13462"},{"taxonomy":"publication_type","embeddable":true,"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/publication_type?post=13462"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}