title: Increased acid resistance of the archaeon, Metallosphaera sedula by adaptive laboratory evolution.
abstract: Extremely thermoacidophilic members of the Archaea such as the lithoautotroph, Metallosphaera sedula, are among the most acid resistant forms of life and are of great relevance in bioleaching. Here, adaptive laboratory evolution was used to enhance the acid resistance of this organism while genomics and transcriptomics were used in an effort to understand the molecular basis for this trait. Unlike the parental strain, the evolved derivative, M. sedula SARC-M1, grew well at pH of 0.90. Enargite (Cu3AsS4) bioleaching conducted at pH 1.20 demonstrated SARC-M1 leached 23.78 % more copper relative to the parental strain. Genome re-sequencing identified two mutations in SARC-M1 including a nonsynonymous mutation in Msed_0408 (an amino acid permease) and a deletion in pseudogene Msed_1517. Transcriptomic studies by RNA-seq of wild type and evolved strains at various low pH values demonstrated there was enhanced expression of genes in M. sedula SARC-M1 encoding membrane complexes and enzymes that extrude protons or that catalyze proton-consuming reactions. In addition, M. sedula SARC-M1 exhibited reduced expression of genes encoding enzymes that catalyze proton-generating reactions. These unique genomic and transcriptomic features support a model for increased acid resistance arising from enhanced control over cytoplasmic pH.
authors: School of Biological Sciences, University of Nebraska-Lincoln, E234 Beadle Center for Genetics, 1901 Vine St., Lincoln, NE, 68588-0666, USA.|School of Minerals Processing and Bioengineering, Central South University, Changsha, China.
authors: Chenbing
authors: C
authors: Ai
authors: School of Biological Sciences, University of Nebraska-Lincoln, E234 Beadle Center for Genetics, 1901 Vine St., Lincoln, NE, 68588-0666, USA.
authors: Samuel
authors: S
authors: McCarthy
authors: School of Biological Sciences, University of Nebraska-Lincoln, E234 Beadle Center for Genetics, 1901 Vine St., Lincoln, NE, 68588-0666, USA.
authors: Valerie
authors: V
authors: Eckrich
authors: School of Biological Sciences, University of Nebraska-Lincoln, E234 Beadle Center for Genetics, 1901 Vine St., Lincoln, NE, 68588-0666, USA.
authors: Deepak
authors: D
authors: Rudrappa
authors: School of Minerals Processing and Bioengineering, Central South University, Changsha, China.
authors: Guanzhou
authors: G
authors: Qiu
authors: School of Biological Sciences, University of Nebraska-Lincoln, E234 Beadle Center for Genetics, 1901 Vine St., Lincoln, NE, 68588-0666, USA. pblum1@unl.edu.
authors: Paul
authors: P
authors: Blum
mesh_terms: D019843:Archaeal Proteins / Q000235:genetics / Q000378:metabolism; D003300:Copper / Q000378:metabolism; D019020:Directed Molecular Evolution; D020869:Gene Expression Profiling; D023281:Genomics; D052836:Heterotrophic Processes; D006863:Hydrogen-Ion Concentration; D009154:Mutation; D016943:Sulfolobaceae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
chemical_list: D019843:Archaeal Proteins; D003300:Copper
keywords: Acidity resistance; Enargite bioleaching; Genome re-sequencing; Metallosphaera sedula; RNA sequencing; Transcriptional responses