Search

The solubilization of phosphate was investigated using apatite and P-containing uranium rock samples in acid solutions. The concentration of soluble phosphate usually increased upon 24-h extraction followed by subsequent precipitation. Uranium solubilization was investigated using leach solutions that contained about 3 g/l ferric iron produced by bacterial oxidation of iron pyrite. 1-94% extraction of uranium was attained within 24h, with the poor recovery associated with a rock sample containing an excessive amount of alkaline material. Reducing equivalents (permanganate-consuming substances) in the acid leach solutions could be oxidized by inoculation with iron-oxidizing thiobacilli ( Thiobacillus ferrooxidans). Chemical analysis of iron indicated that most of the iron was in the oxidized form. Stable iron colloids were not present in significant amounts in the leach solutions. Acidic ferric sulfate containing about 6 g/l Fe was also used as a leach solution. Repeated use of the leach solution with rock samples did not decrease the efficiency of the leaching but soluble uranium reached a toxic concentration and thus prevented the bacterial re-oxidation of ferrous iron in the leach solution. [ABSTRACT FROM AUTHOR]

In this study, we demonstrate that a bacterial isolate Paraccocus versutus XT0.6 from the Xikuangshan antimony mine, the world largest antimony deposit, is capable of stibnite dissolution, oxidation of Sb(III), and formation of secondary Sb(V) bearing mineral. The isolate could oxidize dissolved Sb(III) aerobically and anaerobically. It was able to dissolve Sb(III) in solid minerals, which was subsequently oxidized to Sb(V) completely. Part of Sb(V) was scavenged by the formation of secondary Sb(V)-bearing mineral mopungite [NaSb(OH) 6 ] in the biotic experiments. In contrast, Sb(III) released from mineral/rocks was only partially oxidized to Sb(V) and no secondary Sb-bearing mineral was formed in abiotic controls. These results demonstrated that microbial processes involved in the mobilization, oxidation, and transformation of antimony in minerals/rocks under ambient environmental conditions and offer new insights in biogeochemistry of Sb at mining areas., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Aims: A batch chlorination system was optimized for on-site wastewater treatment and reuse system (OWRS) and its efficiency was evaluated for reducing viruses, protozoa, bacteria and antimicrobial resistance in cold and warm seasons., Methods and Results: The OWRS performance in reducing microbial contaminants was determined by assessing three different faecal indicators (Escherichia coli, F-specific coliphages and Clostridium perfringens for measuring the disinfection efficiency of bacteria, viruses and spore-formers and surrogate for protozoa, respectively) using culture-based methods. Quantitative PCR was used to quantify pathogenic bacteria (Shiga-toxin-producing E. coli (STEC), Campylobacter spp., and Arcobacter spp.), a human-associated faecal marker (gyrB), and tetracycline resistant bacteria (tetQ). The levels of E. coli, coliphages and Cl. perfringens showed 5·4, 2·3, 2·5 log reduction, respectively, upon disinfection. In the final effluents, coliphages (1·7 × 10 2 PFU 100 ml -1 ) and Cl. perfringens (3·4 CFU 100 ml -1 ) were detected in 80 and 100% of the samples, but E. coli was not found. The removal and inactivation of E. coli and Cl. perfringens were not significantly different across the seasons, however, efficacy of removal and inactivation of F-specific coliphage was significantly reduced during the winter/spring season compared to the summer/autumn season (P = 0·009). The reduction of Arcobacter, gyrB and tetQ by 3·1, 2·3 and 2·3 log, respectively, was mostly due to peat biofiltration under the study conditions., Conclusions: This study demonstrated that peat biofiltration was the most important step of the OWRS to remove microbes and genes from wastewater before spray irrigation of the effluents. The irrigation system is not suitable for edible crops because of the potential presence of residual pathogens., Significance and Impact of the Study: On-site wastewater treatment systems are a practical option for reusing the wastewater for landscape, especially for those areas where geological and seasonal limitations impact the removal of microbial contaminants by soil infiltration., (© 2016 The Society for Applied Microbiology.)

Motile swarmer cells of Hyphomicrobium strain W1-1B displayed positive chemotactic responses toward methylamine, dimethylamine, and trimethylamine but did not display significant chemotactic responses towards methanol and arginine. Electron micrographs of negatively stained intact flagellar filaments indicated a novel striated surface pattern. The flagella were composed of two proteins of 39 and 41 kDa. Neither protein was a glycoprotein as determined by Schiff's staining and by enzyme immunoassay. Protein fingerprints visualized from silver-stained polyacrylamide gels and Western blots of protease-digested samples indicated that the two proteins were similar but not identical. Monoclonal antibodies prepared to the complex flagella of Rhizobium meliloti cross-reacted with the striated flagella of Hyphomicrobium strain W1-1B; however, these antibodies did not cross-react with smooth-surface flagella. These results suggest that complex and striated flagella possess homologous epitope regions.

Alachlor, metolachlor, and propachlor are detoxified in biological systems by the formation of glutathione-acetanilide conjugates. This conjugation is mediated by glutathione-S-transferase, which is present in microorganisms, plants, and mammals. Other organic sulfides and inorganic sulfide also react through a nucleophilic attack on the 2-chloro group of acetanilide herbicides, but the products are only partially characterized. Sorption in soils and sediments is an important factor controlling the migration and bioavailability of these herbicides, while microbial degradation is the most important factor in determining their overall fate in the environment. The biodegradation of alachlor and metolachlor is proposed to be only partial and primarily cometabolic, and the ring cleavage seems to be slow or insignificant. Propachlor biodegradation has been reported to proceed to substantial (> 50%) mineralization of the ring structure. Reductive dechlorination may be one of the initial breakdown mechanisms under anaerobic conditions. Aerobic and anaerobic transformation products vary in their polarity and therefore in soil binding coefficient. A catabolic pathway for chloroacetanilide herbicides has not been presented in the literature because of the lack of mineralization data under defined cultural conditions.