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The photosynthetic filamentous bacterium Scytonema sp. strain ING-1 and the microalgo Chlorella sp. strain SA1 are responsible for polishing heavy metals in mine waters by coprecipitating them with hydrozincite. This results in a white mineralized mat on the creek bed that contains high levels of lead, cadmium, nickel, copper and other metals.

The adhesion mechanisms of a new n-alkane-degrading strain of Acinetobacter isolated from the Venice Lagoon and classified as Acinetobacter venetianus during the n-alkane degradation process were investigated. To this end, the adhesion mechanisms of Acinetobacter sp strain RAG-1 as the control strain and the newly isolated A venetianus VE-C3 were compared in terms of their physiological differences via molecular probes and confocal laser-scanning microscopy. Results demonstrated that VE-C3 cells, which have a hydrophilic capsule, can attach to the alkane droplet through the capsular polysaccharides (CPS). This conclusion negates other reports showing that CPS hinders attachment to hydrophobic solid surfaces.

The sulfate-reducing bacteria Desulfovibrio desulfuricans dissolves barium (Ba) from barite (BaSO4) and increases the level of soluble Ba in cultures and sewage sludge from treatment plants. D. desulfuricans accumulates Ba when grown in cultures containing BaSO4 as the sole sulfate source. A lower concentration of accumulated Ba is probably due to the formation of other Ba compounds such as barium sulfide (BaS). The cultured bacterial cells form aggregates with BaSO4 and autofluorescent crystals of BaS.

The concentrations of mercury and methylmercury in several fungi species were measured by means of a variable volume extraction procedure. Experiments were carried out wherein methylmercury was extracted from fungi carpophores C. comatus and C. radians and the humus material beneath them. The total mercury content for the carpophores was also determined. Results the fungi bioaccumulate methylmercury and transform inorganic mercury to methylmercury.

Two strains of Desulfovibrio desulfuricans, one of which synthesizes monomethylmercury from ionic mercury, were cultured to assess methylmercury toxicity and to compare the anaerobic strains of Clostridium pasteurianum. The CH3HgCl resistance of Desulfovibrio desulfuricans strains was 10 times that of Pseudomonas putida FB-1 and 100 times that of Clostridium pasteurianum. An insoluble, decomposable, white dimethyl mercury sulfide, (CH3Hg)2S, was produced in reaction to methyl mercury and hydrogen sulfide.

Pyrite oxidation by Metallosphaera sedula with moderate and high pyritic sulfur content showed that it oxidized mineral pyrite at an enhanced rate.The magnitude of biological stimulation above abiotic rates was significantly less than with mineral pyrites, and the maximum rate of coal depyritization were also enhanced by Metallosphaera sedula. The oxidation of pyrite with ferric ions diminishes coal depyritization, and this has been significantly noticeable due to the maintenance of a high ratio of ferric to ferrous iron in solution by Metallosphaera sedula.

Monomethylmercury is more volatile than inorganic mercuric ions. Methylmercury chloride was combined with aqueous solutions of NaBH4, and the formation of the volatile mercury derivative was studied. This derivatization method was used in conjunction with a Fourier transform infrared spectrometer and a gas chromatograph in the speciation of methylmercury. Hydrogen from NaBH4 reacted with methylmercury chloride in aqueous solution to produce MeHgH, while deuterium from NaBD4 reacted to produce MeHgD.

The oxidation of mineral pyrites and pyritic materials of various chemical reactivities by Thiobacillus ferrooxidans was studied. At 04% pulp density, T. ferrooxidans oxidized the pyritic materials at varying rates, indicating the differences of chemical reactivities of the pyrites. Increasing the pulp density to 2.0% resulted in no pyrite oxidation in the mostchemcally reactive pyrite, while bioleaching was delayed in pyrites derived from coal sources. However, no inhibition of pyrite oxidation was observed for mineral pyrites. The results suggest that evaluation of bioleachers should takeinto consideration the differences in pyrite reactivities during initial studies.

Abstract Background A bacterial strain previously isolated from pyrite mine drainage and named BAS-10 was tentatively identified as Klebsiella oxytoca. Unlikely other enterobacteria, BAS-10 is able to grow on Fe(III)-citrate as sole carbon and energy source, yielding acetic acid and CO2 coupled with Fe(III) reduction to Fe(II) and showing unusual physiological characteristics. In fact, under this growth condition, BAS-10 produces an exopolysaccharide (EPS) having a high rhamnose content and metal-binding properties, whose biotechnological applications were proven as very relevant. Results Further phylogenetic analysis, based on 16S rDNA sequence, definitively confirmed that BAS-10 belongs to K. oxytoca species. In order to rationalize the biochemical peculiarities of this unusual enterobacteriun, combined 2D-Differential Gel Electrophoresis (2D-DIGE) analysis and mass spectrometry procedures were used to investigate its proteomic changes: i) under aerobic or anaerobic cultivation with Fe(III)-citrate as sole carbon source; ii) under anaerobic cultivations using Na(I)-citrate or Fe(III)-citrate as sole carbon source. Combining data from these differential studies peculiar levels of outer membrane proteins, key regulatory factors of carbon and nitrogen metabolism and enzymes involved in TCA cycle and sugar biosynthesis or required for citrate fermentation and stress response during anaerobic growth on Fe(III)-citrate were revealed. The protein differential regulation seems to ensure efficient cell growth coupled with EPS production by adapting metabolic and biochemical processes in order to face iron toxicity and to optimize energy production. Conclusion Differential proteomics provided insights on the molecular mechanisms necessary for anaeorobic utilization of Fe(III)-citrate in a biotechnologically promising enterobacteriun, also revealing genes that can be targeted for the rational design of high-yielding EPS producer strains.