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Lookup NU author(s): Dr Ernest Chi Fru, Emeritus Professor Neil GrayORCiD, Dr Clare McCannORCiD, Dr Joana Baptista, Dr Beate Christgen, Dr Helen Talbot, Adel El-Gheblawi, Professor Christopher Dennison, Professor David GrahamORCiD
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Controls on in situ methanotroph activity are not well understood. One potentially important parameter is copper (Cu) because this metal is at the centre of particulate methane monooxygenase (pMMO), the most active enzyme involved in oxidizing methane to methanol. Furthermore, Cu-to-cell ratios influence the relative expression of pMMO versus the alternate soluble MMO (sMMO) in some species. Most methanotroph studies have only assessed readily soluble forms of Cu (e.g., CuCl2) atypical of real methanotroph habitats and there is a dearth of activity data associated with more common environmental Cu sources. Here we quantified sMMO activity and growth kinetics in Methylosinus trichosporium OB3b, an organism that expresses both pMMO and sMMO, when grown on Cu-minerals with differing dissolution equilibria to assess how mineral source and methanobactin (mb) influences growth. Mb is a molecule produced by M. trichosporium OB3b that has a high affinity for Cu, reduces Cu toxicity, mediates Cu uptake and may be key to Cu availability in terrestrial systems. Abiotic Cu-dissolution experiments showed that Cu release is affected by mb level, although mb only enhances Cu dissolution from sparingly soluble minerals, such as CuO and to a greater extent CuCO3·Cu(OH)2. However, the two minerals affected M. trichosporium OB3b growth very differently. Cells grew without growth lag and with active pMMO on CuCO3·Cu(OH)2, regardless of the amount of mineral supplied (< 500 μmoles Cu-total L−1). In contrast, they also grew well with CuO (< 50 μmoles Cu-total L−1), but instead had active sMMO, although sMMO activity was conditionally suppressed by supplemental mb and-or direct cell-mineral contact. Mb additions significantly increased growth rates (p<0.05) with both minerals. Results show mb broadly stimulates growth, but Cu mineralogy and mb dictate whether sMMO or pMMO is active in the cells. This has implications to in situ bioremediation and other studies on methanotroph function in terrestrial systems.
Author(s): Chi Fru E, Gray ND, McCann C, Baptista JDC, Christgen B, Talbot HM, El Ghazouani A, Dennison C, Graham DW
Publication type: Article
Publication status: Published
Journal: Biogeosciences
Year: 2011
Volume: 8
Pages: 2887-2894
ISSN (print): 1726-4170
ISSN (electronic): 1726-4189
Publisher: Copernicus GmbH
URL: http://dx.doi.org/10.5194/bg-8-2887-2011
DOI: 10.5194/bg-8-2887-2011
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