Identification of Sulfur Activation Relevant Protein Genes of Extremely Thermophilic Acidianus manzaensis

The sulfur activation by extracellular proteins is considered as the crucial stage during biooxidation of elemental sulfur (S0). In order to study genes encoding sulfur-activation related extracellular proteins of extremely thermophilic Acidianus manzaensis, the extracellular proteins with higher abundance for the strain grown on S0 allotropes than that on Fe2+ were first screened by two-dimensional gel electrophoresis, and then identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Nine genes amplified with PCR were satisfactory according to their agarose gel electrophoresis. The differential expression of these nine genes when the strain grown on S0 allotropes and Fe2+ were analyzed with real-time quantitative PCR (RT-qPCR). Results showed that seven of them were higher expressed when the strain grown on S0 allotropes than on Fe2+, indicating they may be related with sulfur activation by A. manzaensis.

Evolution of Compositions and Contents of Capsule and Slime EPSs for Adaptation to and Action on Energy Substrates and Heavy Metals by Typical Bioleaching Microorganisms

Adaption to the energy substrates and heavy metals by bioleaching micoorganisms is the prerequisite for efficient microbe-mineral interaction in bioleaching process. It is known extracellular polymer substances (EPSs) take important role in mediating the adaption to and action on energy substrates and heavy metals. This report presents the evolution of compositions and contents of the major components of EPSs of the typical bioleaching microorganisms (Acidithiobacillus ferrooxidans, Leptospirillum ferriphilum, Sulfobacillus thermosulfidooxidans, and Acidianus manzaensis,) exposed to different energy substrates and heavy metal ions. These strains were acclimated firstly to Fe2+ substrate, and then on the substrates elemental sulfur (S0), pyrite and chalcopyrite, respectively. It was found that the major components of capsule and slime EPSs in terms of proteins, polysaccharides, as well as uronic acids were quite different in contents for the Fe2+-acclimated strains, and they even changed more when the Fe2+-acclimated strains were further acclimated to the other substrates. When exposed to heavy metals, all strains demonstrated much decrease in contents of capsule EPSs, and much increase in slime EPSs contents and the heavy metals were found to bound to the slime parts. It was for the first time the EPSs of the bioleaching strains were fractionated into capsule part and slime part, and it was also for the first time we found the differences in evolution of compositions and contents of the major organic components as well as the inorganic matter of capsule EPSs and slime EPSs when the bioleaching strains were exposed to different energy substrates and heavy metals.

In Situ Characterization of Superficial Organic Composition Changes of Thermoacidophilic Archaea Acidianus manzaensis YN-25 in Response to Energy Substrate

The differences of superficial (about 10 nm) extracellular polymeric substances (EPS) composition of thermoacidophilic archaea Acidianus manzaensis YN-25 acclimated with different energy substrates (FeS2, CuFeS2, S0, FeSO4) were analyzed in situ for the first time by synchrotron radiation (SR) based carbon K-edge X-ray absorption near edge structure (XANES) spectroscopy. The results showed that there are clear associations between the energy substrates and the changes in organic composition in terms of typical function groups (-C=O, -C-O and -C-N). The archaea acclimated with chalcopyrite and pyrite contain higher proportion of proteins but less polysaccharides compared to cells acclimated with S0.The archaea acclimated with FeSO4 contains the highest proportion of protein which is positively associated with the iron oxidation process, while archaea acclimated with S0 contains more lipids and polysaccharides, which may be favorable to the hydrophobic S0 adsorption and utilization processes.