In this study, we present the first metabolic profiles for two bioleaching bacteria using capillary electrophoresis coupled with mass spectrometry. The bacteria, Acidithiobacillus ferrooxidans strain Wenelen (DSM 16786) and Acidithiobacillus thiooxidans strain Licanantay (DSM 17318), were sampled at different growth phases and on different substrates: the former was grown with iron and sulfur, and the latter with sulfur and chalcopyrite. Metabolic profiles were scored from planktonic and sessile states. Spermidine was detected in intra- and extracellular samples for both strains, suggesting it has an important role in biofilm formation in the presence of solid substrate. The canonical pathway for spermidine synthesis seems absent as its upstream precursor, putrescine, was not present in samples. Glutathione, a catalytic activator of elemental sulfur, was identified as one of the most abundant metabolites in the intracellular space in A. thiooxidans strain Licanantay, confirming its participation in the sulfur oxidation pathway. Amino acid profiles varied according to the growth conditions and bioleaching species. Glutamic and aspartic acid were highly abundant in intra- and extracellular extracts. Both are constituents of the extracellular matrix, and have a probable role in cell detoxification. This novel metabolomic information validates previous knowledge from in silico metabolic reconstructions based on genomic sequences, and reveals important biomining functions such as biofilm formation, energy management and stress responses.Electronic supplementary materialThe online version of this article (doi:10.1007/s11306-012-0443-3) contains supplementary material, which is available to authorized users.
We characterize the peculiar velocity field of the local large-scale structure reconstructed from the 2M + + survey, by treating it as a fluid, extracting the gradient and the divergence via different approximations. This reconstructed field is important for cosmology, since it was used to correct the peculiar redshifts of the last SNIA compilation Pantheon+. We conclude that the local velocity field can be described on average as a slightly contracting fluid, with intriguing implications for the "Tilted Cosmology" model. We compute representative values of the apparent deceleration parameter (q) measured by observers inside the contracting region, in order to compare our results with the theoretical predictions of the tilted-universe scenario. As predicted, the computed values are found to be negative on a range of averaged scales, allowing for a possible explanation of dark energy as an effect induced by our peculiar motion relative to the universal expansion.
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