Project description:The study identified a total of 3169 gene transcripts (98.4% coverage). By comparing the anaerobic versus aerobic H2-oxidizing At. ferrooxidans cultures, a total of 371 DEGs were found. Of these, 168 DEGs were increased significantly during the aerobic growth on H2 (with O2 as the sole electron acceptor), while 203 DEGs increased significantly during anaerobic growth on H2 (with Fe3+ as the sole electron acceptor).
Project description:The outer-membrane c-type cytochrome Cyc2 is generally considered to be the initial electron acceptor in iron respiratory chain of Acidithiobacillus ferrooxidans ATCC 23270, a model microorganism in acidophilic bioleaching environment. In our work, however, the knockout of cyc2 did not result in impaired Fe(II) consumption or growth capacity. To screen the potential genes for alternative initial electron acceptors other than Cyc2, RNA-Seq was employed to compare global gene expressions in the A. ferrooxidans ATCC 23270 wild type and the Δcyc2 mutant grown on Fe(II) or switched energy source from S0 to Fe(II). The data focused on 29 up-regulated and 19 down-regulated genes in the mutant under both conditions, among which AFE_1428 was the most highest one. in-silico analysis also suggested that the product of AFE_1428 might act as an alternative initial electron acceptor when Cyc2 was absent, which needs to be further validated.
Project description:Acidithiobacillus ferrooxidans (A. ferrooxidans) ATCC 23270 is a model bacteria for bioleaching research. Because of the use of extractant in metal extraction industry, A. ferrooxidans needs to cope with the water-organic two-phase system. To get insight into the molecular response of A. ferrooxidans to organic solvent, global gene expression pattern was examined in A. ferrooxidans ATCC 23270 cells subjected to Lix984n (an organic extractant) using the method of whole-genome DNA microarray. The data suggested that the global response of A. ferrooxidans to Lix984n stress was characterized by the up-regulation of genes involved in pentose phosphate pathway, fatty acid and glutamate biosynthesis contrary to the significant down-regulation of the majority motility-related genes. In further study, compared to heterotrophic bacteria in dealing with short-time stress, A. ferrooxidans has a special strategy of continuously enhancing the expression of genes encoding proteins involved in electron transport, such as petI, petII, cyo and cyd. Besides, acrAB-tolC operon encoding organic solvent efflux pump and its positive regulator gene ostR were addressed.
Project description:Hydrogen can be an important source of energy for chemolithotrophic acidophiles, especially in the deep terrestrial subsurface. Nevertheless, the current knowledge of microbial hydrogen utilization in acidic environments is minimal. A multi-omics analysis was applied on Acidithiobacillus ferrooxidans growing aerobically and anaerobically (with ferric iron) on hydrogen as an electron donor, and a respiratory model proposed from the results obtained. In this model, both [NiFe] hydrogenases, cytoplasmic uptake and membrane-bound respiratory, oxidize molecular hydrogen to two protons and two electrons. The electrons are used to reduce membrane-soluble ubiquinone to ubiquinol. Genetically associated [FeS]-binding proteins mediate electron relay from the hydrogenases to the ubiquinone pool. Under aerobic conditions, reduced ubiquinol transfers electrons to either cytochrome aa3 oxidase via cytochrome bc1 complex and cytochrome c4 or the alternate directly to cytochrome bd oxidase, resulting in proton efflux together with the reduction of molecular oxygen to water. Under anaerobic conditions, reduced ubiquinol transfers electrons to outer membrane cytochrome c (ferric iron reductase) via cytochrome bc1 complex and a cascade of electron transporters (cytochrome c4, cytochrome c552, rusticyanin, and high potential iron-sulfur protein), resulting in proton efflux together with the reduction of ferric iron to ferrous iron. The proton gradient generated by molecular hydrogen oxidation maintains the membrane potential and allows the generation of ATP via ATP synthase and NADH via NADH-ubiquinone oxidoreductase. To a lesser extent, NADH can also be generated by another bidirectional cytoplasmic hydrogenase. ATP and NADH are further utilized in the Calvin–Benson–Bassham cycle for inorganic carbon uptake and assimilation. These results further clarify the role of extremophiles in biogeochemical processes and their impact on the composition and features of the deep terrestrial subsurface from the distant past to the present.
Project description:Acidithiobacillus ferrooxidans (A. ferrooxidans) ATCC 23270 is a model bacteria for bioleaching research. Because of the use of extractant in metal extraction industry, A. ferrooxidans needs to cope with the water-organic two-phase system. To get insight into the molecular response of A. ferrooxidans to organic solvent, global gene expression pattern was examined in A. ferrooxidans ATCC 23270 cells subjected to Lix984n (an organic extractant) using the method of whole-genome DNA microarray. The data suggested that the global response of A. ferrooxidans to Lix984n stress was characterized by the up-regulation of genes involved in pentose phosphate pathway, fatty acid and glutamate biosynthesis contrary to the significant down-regulation of the majority motility-related genes. In further study, compared to heterotrophic bacteria in dealing with short-time stress, A. ferrooxidans has a special strategy of continuously enhancing the expression of genes encoding proteins involved in electron transport, such as petI, petII, cyo and cyd. Besides, acrAB-tolC operon encoding organic solvent efflux pump and its positive regulator gene ostR were addressed. In this work, the whole-genome array was employed to conduct the time-course transcriptome analysis of A. ferrooxidans ATCC 23270 in response to 1% (v/v) Lix984n for 5, 20, 40, and 80 min.
Project description:To address the question of how quorum sensing controls biofilm formation in Acidithiobacillus ferrooxidans ATCC23270, the transcriptome of this organism in conditions in which quorum sensing response is stimulated by a synthetic acyl homoserine lactone (AHL) analogue has been studied. Tetrazole 9c was used in DNA microarray experiments that allowed the identification of genes regulated by quorum sensing signalling, and more particularly those involved in early biofilm formation.