Ulloa Ricardo, Moya-Beltrán Ana, Rojas-Villalobos Camila, Nuñez Harold, Chiacchiarini Patricia, Donati Edgardo, Giaveno Alejandra, Quatrini Raquel
PROBIEN (CCT Comahue-CONICET, UNCo), Departamento de Química, Facultad de Ingeniería, Universidad Nacional del Comahue, Neuquén, Argentina.
Microbial Ecophysiology Laboratory, Fundación Ciencia & Vida, Santiago, Chile.
Front Microbiol. 2019 Jan 30;10:60. doi: 10.3389/fmicb.2019.00060. eCollection 2019.
Extreme acidophiles play central roles in the geochemical cycling of diverse elements in low pH environments. This has been harnessed in biotechnologies such as biomining, where microorganisms facilitate the recovery of economically important metals such as gold. By generating both extreme acidity and a chemical oxidant (ferric iron) many species of prokaryotes that thrive in low pH environments not only catalyze mineral dissolution but also trigger both community and individual level adaptive changes. These changes vary in extent and direction depending on the ore mineralogy, water availability and local climate. The use of indigenous versus introduced microbial consortia in biomining practices is still a matter of debate. Yet, indigenous microbial consortia colonizing sulfidic ores that have been domesticated, i.e., selected for their ability to survive under specific polyextreme conditions, are claimed to outperform un-adapted foreign consortia. Despite this, little is known on the domestication of acidic microbial communities and the changes elicited in their members. In this study, high resolution targeted metagenomic techniques were used to analyze the changes occurring in the community structure of local microbial consortia acclimated to growing under extreme acidic conditions and adapted to endure the conditions imposed by the target mineral during biooxidation of a gold concentrate in an airlift reactor over a period of 2 years. The results indicated that operative conditions evolving through biooxidation of the mineral concentrate exerted strong selective pressures that, early on, purge biodiversity in favor of a few spp. over other iron oxidizing acidophiles. Metagenomic analysis of the domesticated consortium present at the end of the adaptation experiment enabled reconstruction of the RVS1-MAG, a novel representative of from the Andacollo gold mineral district. Comparative genomic analysis performed with this genome draft revealed a net enrichment of gene functions related to heavy metal transport and stress management that are likely to play a significant role in adaptation and survival to adverse conditions experienced by these acidophiles during growth in presence of gold concentrates.
极端嗜酸菌在低pH环境中多种元素的地球化学循环中发挥着核心作用。这已被应用于生物采矿等生物技术中，在生物采矿中，微生物有助于回收经济上重要的金属，如金。许多在低pH环境中茁壮成长的原核生物物种通过产生极端酸性和一种化学氧化剂（三价铁），不仅催化矿物溶解，还引发群落和个体水平的适应性变化。这些变化的程度和方向因矿石矿物学、水的可利用性和当地气候而异。在生物采矿实践中使用本地微生物群落还是引入的微生物群落仍存在争议。然而，定殖在已驯化的硫化矿石上的本地微生物群落，即因其在特定多极端条件下生存的能力而被选择的群落，据称比未适应的外来群落表现更好。尽管如此，关于酸性微生物群落的驯化及其成员所引发的变化，人们知之甚少。在本研究中，使用高分辨率靶向宏基因组技术分析了当地微生物群落在极端酸性条件下生长并适应在气升式反应器中对金精矿进行生物氧化期间目标矿物所施加条件的群落结构变化，为期2年。结果表明，通过矿物精矿生物氧化演变的操作条件施加了强大的选择压力，早期会清除生物多样性，有利于少数物种而非其他铁氧化嗜酸菌。对适应实验结束时存在的驯化群落进行宏基因组分析，能够重建RVS1-MAG，这是来自安达科洛金矿区的一个新的代表基因组。对该基因组草图进行的比较基因组分析揭示了与重金属运输和应激管理相关的基因功能的净富集，这些功能可能在这些嗜酸菌在金精矿存在下生长期间适应和存活于不利条件中发挥重要作用。
