No abstract

No abstract

No abstract

Wastewater from mining and other industries usually contains arsenic and cyanide, two highly toxic pollutants, thereby creating the need to develop bioremediation strategies. Here, molecular mechanisms triggered by the simultaneous presence of cyanide and arsenite were analyzed by quantitative proteomics, complemented with qRT-PCR analysis and determination of analytes in the cyanide-assimilating bacterium Pseudomonas pseudoalcaligenes CECT 5344. Several proteins encoded by two ars gene clusters and other Ars-related proteins were up-regulated by arsenite, even during cyanide assimilation. Although some proteins encoded by the cio gene cluster responsible for cyanide-insensitive respiration decreased in the presence of arsenite, the nitrilase NitC required for cyanide assimilation was unaffected, thus allowing bacterial growth with cyanide and arsenic. Two complementary As-resistance mechanisms were developed in this bacterium, the extrusion of As(III) and its extracellular sequestration in biofilm, whose synthesis increased in the presence of arsenite, and the formation of organoarsenicals such as arseno-phosphoglycerate and methyl-As. Tetrahydrofolate metabolism was also stimulated by arsenite. In addition, the ArsH2 protein increased in the presence of arsenite or cyanide, suggesting its role in the protection from oxidative stress caused by both toxics. These results could be useful for the development of bioremediation strategies for industrial wastes co-contaminated with cyanide and arsenic.

Cyanide, mercury, and arsenic are considered very toxic chemicals that are present in nature as cocontaminants in the liquid residues generated by different industrial activities like mining. Considering the huge amounts of toxic cyanide- and mercury-containing wastes generated at a large scale and the high biotechnological potential of P. pseudoalcaligenes CECT 5344 in the detoxification of cyanide present in these industrial wastes, in this work, proteomic, transcriptional, and bioinformatic approaches were used to characterize the molecular response of this bacterium to cyanide and mercury, highlighting the mechanisms involved in the simultaneous detoxification of both compounds.

No abstract

No abstract

We ascertained the relationship between the zonal pattern and the pasture vegetation of a volcanic soil polluted with dust from a cement factory after 70 years of operation, with parameters linked to soil microbial activity (soil basal respiration and hydrolases) and physicalchemical properties. Six sampling zones were established at distances of 1, 2, 3, 4, 5 and 6 km away from the cement plant, considering the latter one as the zone where the pastures were unaffected by the cement dust. Plant cover was negatively affected by cement dust, showing a sharp decline with decreasing distance to the cement factory. The values of pH and extractable K were two units and 2·3-fold higher, respectively, in the sampling zone nearest to the factory, in comparison with those in the unaffected zone. The levels of total Cr, Pb, Ni and Cd were normal and did not vary significantly with distance to the cement factory. Soil respiration and the protease, phosphomonoesterase and β-glucosidase activities declined significantly with decreasing distance to the cement factory. Urease activity was only decreased in the zone nearest to the factory, in comparison with that in the unaffected zone. The soil respiration and hydrolase activities were correlated positively with soil organic matter and plant cover and negatively with soil pH and extractable K concentration. The prolonged exposure to cement dust has resulted in shifts in the soil microbial function, which follows a spatial pattern related to soil alkalization and the decrease in pasture production.