Exploring the use of Acidithiobacillus Ferrooxidans for the removal of Sulphides from Tarnished Silver

Tarnished silver objects contain a black layer of silver sulfide. Current cleaning methods are not suitable for fragile objects, therefore, this exploratory study set out to develop a new biology-based method to clean silver. The extremophile bacterium Acidithiobacillus ferrooxidans was considered the most promising candidate, because of its ability to oxidize metal sulfides. The bacterium indirectly removed silver sulfide from tarnished silver coupons, through the generation of ferric iron. However, this procedure etched the silver. It was investigated whether A. ferrooxidans was able to directly oxidize silver sulfide in the absence of iron. However, no removal of silver sulfide was observed

The type II secretion system (Xcp) of Pseudomonas putida is active and involved in the secretion of phosphatases.

The genome of the Gram-negative bacterium Pseudomonas putida harbours a complete set of xcp genes for a type II protein secretion system (T2SS). This study shows that expression of these genes is induced under inorganic phosphate (Pi ) limitation and that the system enables the utilization of various organic phosphate sources. A phosphatase of the PhoX family, previously designated UxpB, was identified, which was produced under low Pi conditions and transported across the cell envelope in an Xcp-dependent manner demonstrating that the xcp genes encode an active T2SS. The signal sequence of UxpB contains a twin-arginine translocation (Tat) motif as well as a lipobox, and both processing by leader peptidase II and Tat dependency were experimentally confirmed. Two different tat gene clusters were detected in the P.?putida genome, of which one, named tat-1, is located adjacent to the uxpB and xcp genes. Both Tat systems appeared to be capable of transporting the UxpB protein. However, expression of the tat-1 genes was strongly induced by low Pi levels, indicating a function of this system in survival during Pi starvation

Impacts of meeting minimum access on critical earth systems amidst the Great Inequality

The Sustainable Development Goals aim to improve access to resources and services, reduce environmental degradation, eradicate poverty and reduce inequality. However, the magnitude of the environmental burden that would arise from meeting the needs of the poorest is under debate—especially when compared to much larger burdens from the rich. We show that the ‘Great Acceleration’ of human impacts was characterized by a ‘Great Inequality’ in using and damaging the environment. We then operationalize ‘just access’ to minimum energy, water, food and infrastructure. We show that achieving just access in 2018, with existing inequalities, technologies and behaviours, would have produced 2–26% additional impacts on the Earth’s natural systems of climate, water, land and nutrients—thus further crossing planetary boundaries. These hypothetical impacts, caused by about a third of humanity, equalled those caused by the wealthiest 1–4%. Technological and behavioural changes thus far, while important, did not deliver just access within a stable Earth system. Achieving these goals therefore calls for a radical redistribution of resources

A metagenomic portrait of the microbial community responsible for two decades of bioremediation of poly-contaminated groundwater

Biodegradation of pollutants is a sustainable and cost-effective solution to groundwater pollution. Here, we investigate microbial populations involved in biodegradation of poly-contaminants in a pipeline for heavily contaminated groundwater. Groundwater moves from a polluted park to a treatment plant, where an aerated bioreactor effectively removes the contaminants. While the biomass does not settle in the reactor, sediment is collected afterwards and used to seed the new polluted groundwater via a backwash cycle. The pipeline has successfully operated since 1999, but the biological components in the reactor and the contaminated park groundwater have never been described. We sampled seven points along the pipeline, representing the entire remediation process, and characterized the changing microbial communities using genome-resolved metagenomic analysis. We assembled 297 medium- and high-quality metagenome-assembled genome sequences representing on average 46.3% of the total DNA per sample. We found that the communities cluster into two distinct groups, separating the anaerobic communities in the park groundwater from the aerobic communities inside the plant. In the park, the community is dominated by members of the genus Sulfuricurvum, while the plant is dominated by generalists from the order Burkholderiales. Known aromatic compound biodegradation pathways are four times more abundant in the plant-side communities compared to the park-side. Our findings provide a genome-resolved portrait of the microbial community in a highly effective groundwater treatment system that has treated groundwater with a complex contamination profile for two decades

Molecular analysis of the promoter region of the Escherichia coli K-12 phoE gene : Identification of an element, upstream from the promoter, required for efficient expression of phoE protein

The phoE gene of Escherichia coli codes for an outer membrane pore protein whose expression is induced under phosphate limitation. The promoter of this gene contains a 17 base-pair fragment, designated a pho box, which is present also in other phosphatecontrolled promoters. The mRNA start site was determined and found to be located downstream from the pho box, such that this element is located in the −35 region of the phoE promoter. A set of promoter deletions was generated in vitro and analysis of these deletions revealed that sequences upstream from the pho box are required for the efficient expression of phoE. The required upstream region is located (in part) between positions −106 and −121 relative to the mRNA start site, and contains sequences homologous to a pho box and a correctly spaced Pribnow box, but in the reversed orientation relative to the regular −35 and −10 regions. A proper spacing between this upstream region and the −35 region appears to be important, since an oligonucleotide insertion in the intervening region interferes with phoE expression. By cloning the upstream region in a lacZ operon fusion vector, a weak phosphate limitation-inducible promoter activity could be detected