Study On The Molecular Mechanism Of Sulfide Minerals Leaching By Mixed Moderate Thermophiles

Different types of leaching microorganisms interactions can improve the leaching efficiency.A co-culture system constructed by Leptospirillum ferriphilum,Acidithiobacillus caldus and Sulfobacillus thermosulfidooxidans was used as the research object.The bacteria with stable leaching rate were obtained through domestication by increasing pulp density.The parameter changes,community dynamics of free and attached cells of bornite,chalcopyrite and pyrite-leaching systems were explored.The label free proteomics were used to characterized the bornite leaching system in different periods,the expression differences of key functional proteins were analyzed.The molecular mechanism of mixed moderate thermophiles in the leaching process of sulfide minerals was studied.It provides a theoretical basis for the regulation of functional populations and parameters for industrial biometallurgy.Mixed moderate thermophiles that can tolerate 10% pulp density was obtained through domestication,and the leaching rate was higher than that of the untamed bacteria.The results showed that in the process of domestication of the same minerals,with the increase of pulp density,the maximum redox potential value showed a decreasing trend,and the leaching rate decreased.Leaching of bornite,chalcopyrite and pyrite by mixed moderate thermophiles was investigated.The results showed that the leaching rates of copper in bornite reached 91.8% on the 24 th day,the leaching rate of copper in chalcopyrite reached 70.86% on the 40 th day,and the leaching rate of iron of pyrite reached 90.2% on the 20 th day.Scanning electron microscopy results showed that there was obvious microbial corrosion on the surfaces of bornite,chalcopyrite and pyrite.The results of X-ray diffraction and X-ray photoelectron spectroscopy indicate that the slag of bornite,chalcopyrite and pyrite contains jarosite,and the leaching slag of bornite and chalcopyrite contains elemental sulfur.16 S r RNA sequencing and redundancy analysis investigated the attached and free microbial dominant populations of sulfide ores at different leaching times.The results indicated that the dominant bacteria in bornite bioleaching system were free L.ferriphilum,the chalcopyrite were adttached A.caldus and free L.ferriphilum,and the pyrite were attached A.caldus and free S.thermosulfidooxidans,iron and sulfur oxidizing bacteria,attached and free bacteria work together to improve the leaching rate of minerals.Label free quantitative proteomics analysis of proteins in different periods of bornite leaching.Compared with the early leaching stage,717 proteins were up-regulated and 1349 were down-regulated in the middle leaching stage;622 proteins were up-regulated and 1275 were down-regulated in the late leaching stage.Differential proteins were expressed differently in carbon and nitrogen metabolism,iron-sulfur oxidation,metal resistance,and acid-resistance mechanisms.In the early stage,A.caldus and S.thermosulfidooxidans fixed carbon dioxide through the Calvin-Benson-Bassham cycle,and used nitrate or nitrite as nitrogen source,A.caldus was responsible for sulfur oxidation,S.thermosulfidooxidans was responsible for iron oxidation,L.ferriphilum in the middle and late stages fixes carbon dioxide through the reductive tricarboxylic acid cycle pathway,can only absorb ammonium,was responsible for iron oxidation,and S.thermosulfidooxidans was involved in sulfur oxidation.Microorganisms respond to heavy metal and low p H stress by increasing protein synthesis,reducing oxidative stress,accumulating extracellular polymeric substance and forming biofilms,the microorganisms achieve efficient leaching of bornite through time-complementary cooperation.