| Lithium was an essential trace element in organisms,and it was tissue-specifically distributed in animals.Too low lithium content had a negative impact on the body's metabolism.Compared with other heavy metal ions such as nickel,chromium,selenium and arsenic,the toxicity of excessive lithium was not obvious.Lithium was clinically used in the treatment of bipolar disorder,and it also played a neuroprotective role in the treatment of neurological diseases such as Parkinson's disease,traumatic brain injury,Alzheimer's disease and ischemic stroke.Lithium was widely distributed in natural environments.As a low-carbon energy metal,it has attracted much attention.The total amount of brine lithium predominates in lithium ore resources.However,due to the long production cycle of brine extraction and the susceptibility to weather,the production of brine extraction was inefficient.Therefore,ore extraction had become the main way to obtain lithium since 2018.Lithium extraction process from ore included sulfuric acid method,alkali method,sulfate roasting method and chlorination roasting method etc.But there were widespread problems of heavy pollution,large investment,high energy consumption,difficult operation and low safety.Microorganisms had a complex regulatory effect on the metal occurrence state and mineral phase transformation in nature.Microbial leaching technology provided new ideas for innovating lithium extraction from hard rock lithium ore.Compared with traditional leaching technology,microbial leaching technology can improve the economic value of low-grade minerals and tailings,and improve the problems of environmental pollution.It had been found that microorganisms can significantly change the stability of lithium minerals and the geochemical behavior of lithium,but microbial research related to weathering of lithium minerals was very lacking.This article intended to analyze the composition and diversity of microbial communities on the surface of ore and weathering product,through the screening of functional lithium-resistant strains and the study of the lithium leaching function.Recognization and understanding the relationship between the geochemical behavior of lithium and the changes in the microbial communities provide an important basis for the screening of functional bacteria for lithium ore bioleaching.Pegmatite-type and granite-type lithium deposits were the most main types of lithium deposits.Therefore,it is of great significance to reveal the microbial communities and to obtain functional strains for lithium extracting in the pegmatite-type lithium deposits in Nanyangshan of Lushi(Henan)and in granite-type lithium deposits in Yichun(Jiangxi).First,based on 16S r DNA high-throughput sequencing,we analyzed the differences in the distribution characteristics of bacterial communities and their origins among pegmatite-type lithium deposits and granite-type lithium and their weathering products.The results showed that there were differences in the bacterial communities on the surface of lithium ore and its weathering products in the two mines.The OTUs of these samples(NK-1,NK-1F,YK-1,YK-1F,YK-2,YK-2F,YK-3)were 1010,540,835,828,1117,974 and 604respectively,and the difference was significantly related to the different mineral composition.At the phylum level,Actinobacteria and Proteobacteria were dominant phyla in both mines.At the same time,the composition of bacterial communities in the two mines was significantly different(P<0.05),and the differences in weathering product samples from different geographical locations were particularly significant(P<0.001);at the genus level,the genera with relative abundance greater than 5%were Sphingomonas and Massilia in NK-1;Paenibacillus,Bacillus and Massilia in NK-1F;Blastococcus,Candidatus-Solibacter,Noviherbaspirillum and Burkholderia-Caballeronia-Paraburkholderia in YK-1F;unidentified-Chloroplast in YK-2;Kitasatospora and Massilia in YK-2F;1174-901-12 and Methylobacterium in YK-3.The mineral composition was a key factor affecting the community structure,the bacterial species on the surface of pegmatite-type lithium ore and sodiumized granite-type lithium ore were more abundant than their weathered products,which was related to the complex mineral composition of the ores.Proteobacteria,Actinobacteria,Cyanobacteria and Firmicutes were confirmed as the characteristic dominant phyla in the two mining areas.The dominant phyla may adapt to and affect geological habitats by organic matter catabolism,secretion of secondary metabolites,and autotrophic energy and the main functional genes were metabolic functions,such as secondary product metabolism,energy metabolism,and amino acid metabolism.Second,based on ITS1 high-throughput sequencing,we analyzed the differences of fungal communities and the origins among the surface ore and weathering products of the Yichun Lithium Mine.The results showed that there were differences in the fungal communities among the surface of the lithium ore and its weathering products.The OTUs of these samples(YK-1,YK-1F,YK-2,YK-2F,YK-3,YK-4)were 472,624,352,410,305,and 280,respectively.The difference was significantly related to different composition and weathering degree.Each sample of the mine had its own predominant fungi.At the phylum level,Ascomycota and Basidiomycota as the dominant phyla.At the same time,there were significant differences in the composition of fungal communities(P<0.05),and the differences in weathering product from different geographical locations were particularly significant(P<0.001);at the genus level,the genera with relative abundance greater than 5%were Trimorphomycetaceae-unidentified and Trichoderma in YK-1F;Fusarium in YK-1;Thelephoraceae in YK-2F;Chaetothyriales and Trapelia YK-2;Exophiala and Capnobotryella in YK-3;Irpex and Fusarium in YK-4.The nutrient types of mine fungi can be identified as 10 different nutrient types,including pathogenic nutrition,symbiotic nutrition,pathogen-saprophytic-symbiotic nutrition,etc.The dominant functional groups in each sample had their own characteristics,and the saprophytic bacterial group was the dominant group.Its metabolism was characterized by the decomposition of environmental organic matter by hydrolytic enzymes and oxidases.Based on the analysis of bacterial communities in the two mining areas,we took the surface ore and its weathering products NK-1 and NK-1F from the pegmatite-type lithium deposits in Nanyangshan of Lushi(Henan)to screen and isolate 4 strains of lithium-resistant strains N1,N2,W1 and W2,N1 belonging to Bacillus,N2 belonging to Exiguobacterium,W1 belonging to Pseudomonas,and W2 belonging to Arthrobacter.The 4 lithium-tolerant strains all had certain enrichment effects on Li Cl.When the Li~+concentration in the solution was 63.88 mg/L,the adsorption rates of N1,N2,W1,and W2 were 22%,26%,28%,and 40%respectively.At the same time,all these strains of lithium-resistant bacteria can leach lithium from spodumene.W2 had the highest leaching capacity,and the Li~+concentration can reach4.332 mg/L in the culture medium after 30 days incubation.The results of scanning electron microscopy showed that 4 lithium-resistant bacteria adhered and interacted with spodumene.There were many secondary minerals on the surface of spodumene containing N1 and W2,with obvious bacterial erosion.The surface of spodumene containing N2 had very regular columnar pits,which gradually deepen and widen.The adhension ability of W1 strain was significantly higher than that of N1,N2 and W2 strains.Moreover,4 strains of lithium-resistant bacteria had significant differences in the accumulation of Li~+in the solution and the leaching ability of spodumene,which may be closely related to the metabolic characteristics of different strains,the interaction with spodumene and the erosion mechanism.In this work,we reveal that there are significant differences in the bacterial and fungal diversity of lithium ore and its weathering products in different regions.Each sample has predominant groups.The functional prediction suggests that Firmicutes,Cyanobacteria,Ascomycota,Basidiomycota,and Massilia have a dominant position,which is closely related to the metabolic functions of these microorganisms,such as secondary product metabolism,energy metabolism,and amino acid metabolism.The 4 strains of in-situ lithium-tolerant functional strains obtained have the function of enriching lithium and can corrode the spodumene to lithium enrichment.They also have obvious differences in the mechanism of absorbing lithium and decomposing spodumene.In summary,the present work provides new data for the study of the ecological distribution of microorganisms and the decomposition of minerals by microorganisms.The leaching mechanism of the 4 functional bacteria and their high-efficiency lithium-enrichment capacity laid the foundation for subsequent research and technical application. |
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