Department of Environmental Sciences, Rutgers University, New Brunswick, NJ, USA.
Environ Microbiol. 2013 Oct;15(10):2748-60. doi: 10.1111/1462-2920.12136. Epub 2013 Jun 5.
Strain MPA-C3 was isolated by incubating arsenic-bearing sediments under anaerobic, mesophilic conditions in minimal media with acetate as the sole source of energy and carbon, and As(V) as the sole electron acceptor. Following growth and the respiratory reduction of As(V) to As(III), a yellow precipitate formed in active cultures, while no precipitate was observed in autoclaved controls, or in uninoculated media supplemented with As(III). The precipitate was identified by X-ray diffraction as alacranite, As8 S9 , a mineral previously only identified in hydrothermal environments. Sequencing of the 16S rRNA gene indicated that strain MPA-C3 is a member of the Deferribacteres family, with relatively low (90%) identity to Denitrovibrio acetiphilus DSM 12809. The arsenate respiratory reductase gene, arrA, was sequenced, showing high homology to the arrA gene of Desulfitobacterium halfniense. In addition to As(V), strain MPA-C3 utilizes NO3(-), Se(VI), Se(IV), fumarate and Fe(III) as electron acceptors, and acetate, pyruvate, fructose and benzoate as sources of carbon and energy. Analysis of a draft genome sequence revealed multiple pathways for respiration and carbon utilization. The results of this work demonstrate that alacranite, a mineral previously thought to be formed only chemically under hydrothermal conditions, is precipitated under mesophilic conditions by the metabolically versatile strain MPA-C3.
MPA-C3 菌株是在厌氧、中温条件下，在最小培养基中用乙酸作为唯一的能源和碳源，以及 As(V) 作为唯一的电子受体培养含砷沉积物而分离得到的。在生长和 As(V)呼吸还原为 As(III)之后，活性培养物中形成了黄色沉淀物，而在灭菌对照物或未接种但添加了 As(III)的培养基中则没有观察到沉淀物。通过 X 射线衍射鉴定，沉淀物为 alacranite，As8S9，这是一种以前仅在热液环境中鉴定出的矿物。16S rRNA 基因测序表明，MPA-C3 菌株是 Deferribacteres 科的成员，与 Denitrovibrio acetiphilus DSM 12809 的相似度相对较低（90%）。测序了砷酸盐呼吸还原酶基因 arrA，其与 Desulfitobacterium halfniense 的 arrA 基因具有高度同源性。除了 As(V)，MPA-C3 菌株还利用 NO3(-)、Se(VI)、Se(IV)、延胡索酸和 Fe(III)作为电子受体，以及乙酸盐、丙酮酸盐、果糖和苯甲酸作为碳和能源的来源。对一个基因组草图的分析揭示了多种呼吸和碳利用途径。这项工作的结果表明，alacranite 是一种以前认为只能在热液条件下通过化学方式形成的矿物，但代谢多功能的 MPA-C3 菌株在中温条件下沉淀了这种矿物。
