Skouri-Panet Fériel, Benzerara Karim, Cosmidis Julie, Férard Céline, Caumes Géraldine, De Luca Gilles, Heulin Thierry, Duprat Elodie
Centre National de la Recherche Scientifique, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Sorbonne Universités, UMR 7590, Muséum National d'Histoire Naturelle, Université Pierre et Marie Curie, IRD 206, Paris, France.
Department of Geological Sciences, University of Colorado, Boulder, CO, United States.
Front Microbiol. 2018 Jan 11;8:2592. doi: 10.3389/fmicb.2017.02592. eCollection 2017.
Microbial phosphatase activity can trigger the precipitation of metal-phosphate minerals, a process called phosphatogenesis with global geochemical and environmental implications. An increasing diversity of phosphatases expressed by diverse microorganisms has been evidenced in various environments. However, it is challenging to link the functional properties of genomic repertoires of phosphatases with the phosphatogenesis capabilities of microorganisms. Here, we studied the betaproteobacterium (), known to biomineralize Ca-phosphates in the environment and the laboratory. We investigated the functional repertoire of this biomineralization process at the cell, genome and molecular level. Based on a mineralization assay, is shown to hydrolyse the phosphoester bonds of a wide range of organic P molecules. Accordingly, its genome has an unusually high diversity of phosphatases: five genes belonging to two non-homologous families, and , were detected. These genes showed diverse predicted cis-regulatory elements. Moreover, they encoded proteins with diverse structural properties according to molecular models. Heterologously expressed PhoD and PhoX in had different profiles of substrate hydrolysis. As evidenced for cells, recombinant cells induced the precipitation of Ca-phosphate mineral phases, identified as poorly crystalline hydroxyapatite. The phosphatase genomic repertoire of (containing phosphatases of both the PhoD and PhoX families) was previously evidenced as prevalent in marine oligotrophic environments. Interestingly, the Tataouine sand from which was isolated showed similar P-depleted, but Ca-rich conditions. Overall, the diversity of phosphatases in allows the hydrolysis of a broad range of organic P substrates and therefore the release of orthophosphates (inorganic phosphate) under diverse trophic conditions. Since the release of orthophosphates is key to the achievement of high saturation levels with respect to hydroxyapatite and the induction of phosphatogenesis, appears as a particularly efficient driver of this process as shown experimentally.
微生物磷酸酶活性可引发金属磷酸盐矿物的沉淀，这一过程称为磷酸化作用，具有全球地球化学和环境意义。在各种环境中，已证实不同微生物表达的磷酸酶种类越来越多。然而，将磷酸酶基因组库的功能特性与微生物的磷酸化能力联系起来具有挑战性。在这里，我们研究了β-变形杆菌（），已知其在环境和实验室中能生物矿化钙磷酸盐。我们在细胞、基因组和分子水平上研究了这种生物矿化过程的功能库。基于矿化分析，显示能水解多种有机磷分子的磷酸酯键。因此，其基因组具有异常高的磷酸酶多样性：检测到属于两个非同源家族和的五个基因。这些基因显示出不同的预测顺式调控元件。此外，根据分子模型，它们编码具有不同结构特性的蛋白质。在中异源表达的PhoD和PhoX具有不同的底物水解谱。正如细胞所证实的，重组细胞诱导了磷酸钙矿相的沉淀，鉴定为结晶度差的羟基磷灰石。（包含PhoD和PhoX家族的磷酸酶）的磷酸酶基因组库先前已证实在海洋贫营养环境中普遍存在。有趣的是，从中分离出的塔塔乌因沙显示出类似的贫磷但富钙条件。总体而言，中的磷酸酶多样性允许水解多种有机磷底物，因此在不同的营养条件下释放正磷酸盐（无机磷酸盐）。由于正磷酸盐的释放是实现相对于羟基磷灰石的高饱和度水平和诱导磷酸化作用的关键，如实验所示，似乎是这一过程的特别有效驱动因素。
