{"id":13690,"date":"2019-06-17T15:36:24","date_gmt":"2019-06-17T22:36:24","guid":{"rendered":"https:\/\/www.darkenergybiosphere.org\/?post_type=publication&#038;p=13690"},"modified":"2019-06-27T12:49:52","modified_gmt":"2019-06-27T19:49:52","slug":"the-effect-of-o2-and-pressure-on-thiosulfate-oxidation-by-thiomicrospira-thermophila","status":"publish","type":"publication","link":"https:\/\/www.darkenergybiosphere.org\/publication\/the-effect-of-o2-and-pressure-on-thiosulfate-oxidation-by-thiomicrospira-thermophila\/","title":{"rendered":"The effect of O<sub>2<\/sub> and pressure on thiosulfate oxidation by <em>Thiomicrospira thermophila<\/em>"},"content":{"rendered":"<p>Microbial sulfur cycling in marine sediments often occurs in environments characterized by transient chemical gradients that affect both the availability of nutrients and the activity of microbes. High turnover rates of intermediate valence sulfur compounds and the intermittent availability of oxygen in these systems greatly impact the activity of sulfur\u2010oxidizing micro\u2010organisms in particular. In this study, the thiosulfate\u2010oxidizing hydrothermal vent bacterium\u00a0<i>Thiomicrospira thermophila<\/i>\u00a0strain EPR85 was grown in continuous culture at a range of dissolved oxygen concentrations (0.04\u20131.9\u00a0mM) and high pressure (5\u201310\u00a0MPa) in medium buffered at pH 8. Thiosulfate oxidation under these conditions produced tetrathionate, sulfate, and elemental sulfur, in contrast to previous closed\u2010system experiments at ambient pressure during which thiosulfate was quantitatively oxidized to sulfate. The maximum observed specific growth rate at 5\u00a0MPa pressure under unlimited O<sub>2<\/sub>\u00a0was 0.25\u00a0hr<sup>\u22121<\/sup>. This is comparable to the\u00a0<i>\u03bc<\/i><sub>max<\/sub>\u00a0(0.28\u00a0hr<sup>\u22121<\/sup>) observed at low pH (&lt;6) at ambient pressure when\u00a0<i>T.\u00a0thermophila<\/i>\u00a0produces the same mix of sulfur species. The half\u2010saturation constant for O<sub>2<\/sub>\u00a0(K<sub>O2<\/sub>) estimated from this study was 0.2\u00a0mM (at a cell density of 10<sup>5<\/sup>\u00a0cells\/ml) and was robust at all pressures tested (0.4\u201310\u00a0MPa), consistent with piezotolerant behavior of this strain. The cell\u2010specific\u00a0K<sub>O2<\/sub>\u00a0was determined to be 1.5 pmol O<sub>2<\/sub>\/cell. The concentrations of products formed were correlated with oxygen availability, with tetrathionate production in excess of sulfate production at all pressure conditions tested. This study provides evidence for transient sulfur storage during times when substrate concentration exceeds cell\u2010specific\u00a0K<sub>O2<\/sub>\u00a0and subsequent consumption when oxygen dropped below that threshold. These results may be common among sulfur oxidizers in a variety of environments (e.g., deep marine sediments to photosynthetic microbial mats).<\/p>\n","protected":false},"template":"","tags":[],"publication_type":[19],"_links":{"self":[{"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/publication\/13690"}],"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=13690"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/tags?post=13690"},{"taxonomy":"publication_type","embeddable":true,"href":"https:\/\/www.darkenergybiosphere.org\/wp-json\/wp\/v2\/publication_type?post=13690"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}