Study On The Weathering Effect Of Huangshan Rocks By 8 Kinds Of Fungi

Huangshan granite rock mass is hard,difficult to be corroded by acid and alkali,and not easy to be weathered,and it is difficult for Pinus taiwanensis to absorb nutrients from it.Studies have shown that fungi have a strong weathering effect on rocks,the organic acids secreted by fungi can combine with mineral elements in the rock and have a strong dissolution effect on mineral elements.Under liquid culture conditions,this project studied the weathering effects of 6 strains isolated and purified from the P.taiwanensis forest and 2 kinds of ectomycorrhizal fungi symbiosis with the P.taiwanensis on Huangshan rocks(3 of the 8 fungi belong to ectomycorrhizal fungi,and all of them are symbiotic with P.taiwanensis).First,the weathering was studied from the aspect of biomechanics,scanning electron microscope was used to observe the ability of mycelium to adsorb and wrap the rock,X-ray diffractometer(XRD)were used to determine the mineral composition of the rock before and after weathering,and the energy spectrometer was used to measure the change of elements on the rock surface before and after weathering;then we studied it from the aspect of biochemistry,the p H value,the content of organic acids and extracellular polysaccharides,and the types of small molecule metabolites in 8 kinds of fungi culture solution containing rock powder and 8 kinds of fungi culture solution without rock powder were measured;atomic absorption spectrophotometer and reagent method were used to determine the amount of ions dissolved in the culture solution;a strain of fungus with the best weathering ability-Suillus luteus was screened out;the process and mechanism of the weathering of S.luteus and its metabolites on Huangshan rocks were studied.The main research results were presented as following:(1)The 6 kinds of fungi were separated.After ITS sequence analysis and comparison in NCBI,the 6 strains were determined to be the fungi Hypomyces chrysospermus SDM-06(SRR13589361),Cordyceps farinosa SDM-05(SRR13589362),Gliocladium roseum SDM-04(SRR13589363),Suillus luteus SDM-03(SRR13589364),Irpex lacteus SDM-02(SRR13589365),Lenzites betulina SDM-01(SRR12777481).(2)Scanning electron microscope(SEM)was used to observe the surface microscopic changes of the rock particles in the culture solution of 8 kinds of fungi.By observing the looseness of the rock particle structure,the degree of cuttings off,the degree of roundness of edges and corners and the adsorption of mycelium on the rock,it was found that among the 8 kinds of fungi,the most effective one was S.luteus,followed by H.chrysospermus.The SEM image showed that the rock particles covered by the mycelium of S.luteus were loosely structured,the cuttings fall off,the edges and corners were smooth,the mycelium penetrated the rock surface,leaving traces of mycelium,pierced into the cracks in the rock,destroyed the mineral crystal lattice.The hyphae and spores of H.chrysospermus adhered along the rock particles had holes and the whole was loose.(3)XRD was used to determine the composition of the solid residue—mycelium rock polymer.The XRD patterns of the solid residue after the action of 8 kinds of fungi showed that the diffraction peaks of quartz and albite changed significantly compared with other minerals.Because minerals undergo a mineral transformation during the weathering process,that was minerals with a layered structure may transform into a framework structure during the process of being weathered by fungi.Among them,the largest change in mineral composition was S.luteus.In its XRD pattern,the diffraction peaks of various minerals were significantly reduced,and the secondary mineral diffraction peaks were found in the XRD pattern of S.luteus.(4)Energy spectrometer(EDS)was used to analyze the changes in the content and types of mineral elements on the rock surface after the action of 8 kinds of fungi under liquid culture conditions.Compared with the elements(C,O,Na,Al,Si,K,Fe,Mg,Ti,Mn,F)scanned on the rock surface without being treated by fungi;C,O,P,K,C,Fe were scanned on the rock surface after being treated by S.luteus;C,O,Na,Al,Si,K,Ca were scanned on the rock surface after being treated by H.chrysospermus;C,O,Al,Si,K,Fe,Na were scanned on the rock surface after being treated by L.volemus;C,O,Na,Al,Si,K,Fe were scanned on the rock surface after being treated by T.felleus;C,O,Mg,Al,Si,K,Fe,Ca were scanned on the rock surface after being treated by L.betulina;C,O,Mg,Al,Si,K,Fe,Ti,Mn,P,F,Na were scanned on the rock surface after being treated by G.roseum;C,O,Mg,Al,Si,K,Fe,Ca,Na were scanned on the rock surface after being treated by I.lacteus;C,O,Al,Si,K,Fe,Ca,P,Cl were scanned on the rock surface after being treated by C.farinosa;the atomic percentage of C on the surface of rock after the treated of each fungus increased,and the rest decreased.(5)Atomic absorption spectrophotometer and reagent method were used to determine the amount of main ions in the weathered culture medium containing fungi and the weathered culture medium without fungi(control).The results showed that the ion dissolution in the weathering culture solution of 8 kinds of fungi was significantly increased compared with that in the control group,the content of Si⁴⁺,K⁺,P⁵⁺,Al³⁺in the weathering culture solution of S.luteus was the highest among the 8kinds of fungi,which were(mg/L)37.315,104.1,2.02,0.553,respectively,the content of Fe³⁺and Ca²⁺in the weathering solution of H.chrysospermus and I.lacteus were the highest among the 8 kinds of fungi,which were(mg/L)4.958 and 2.53respectively.(6)The p H value,organic acid content,extracellular polysaccharide content,and small molecular metabolites in fungal culture medium containing rock powder and fungal culture medium not containing rock powder(control)were measured.The results showed that the p H value of the L.volemus,S.luteus,H.chrysospermus,C.farinosa,G.roseum,T.felleus,I.lacteus culture medium containing rock powder was lower than the p H value of their control group except for the fungus.There were significant differences in the organic acid content of the 8 kinds of fungi in the culture medium containing rock powder compared with their control at different periods.The content(g/L)of oxalic acid,citric acid,malic acid,and acetic acid in the S.luteus culture medium containing rock powder was the highest among the 8 kinds of fungi,which were 2.046,1.322,1.014,0.481,respectively,and was all higher than that the content of oxalic acid,citric acid,malic acid,and acetic acid(g/L)in the S.luteus culture medium without rock powder was 1.301,0.856,0.871,0.373,respectively.The succinic acid produced in the L.volemus culture medium containing rock powder and the lactic acid produced in the L.betulina culture medium containing rock powder were the highest among the 8 kinds of fungi,which were(g/L)0.812 and 0.301respectively.The polysaccharide content in the culture medium of the 8 kinds of fungi containing rock powder was significantly higher than that in the culture medium without rock powder.The content of polysaccharides(g/L)in the S.luteus,H.chrysospermus,L.betulina,L.volemus,G.roseum,Irpex lacteus,T.felleus,C.farinosa culture medium containing rock powder(g/L)were:14.06,12.76,10.47,9.07 7.83,5.63,5.42,5.06 respectively;the content of polysaccharides in the 8 kinds of fungi culture medium without rock powder(g/L)were:9.15,8.19,8.25,7.21,4.87,5.2,4.06,2.85 respectively.In the culture medium containing rock powder,except for G.roseum and C.farinosa,the types and peak area of small molecular metabolites produced by other fungal were significantly increased compared with those culture medium without containing rock powder;among them,the peak area of 1,6-dehydrated?-d-glucopyranose,disaccharide,acetone alcohol,silanediol and tetramethylsilane were larger,which may contribute to weathering.(7)Among the 8 kinds of fungi,S.luteus had the best weathering effect on Huangshan rocks.The weathering mechanism of its metabolites-organic acids and exopolysaccharides on Huangshan rocks was studied.SEM/EDS,atomic absorption spectrophotometer and reagent method were used to measure and analyse the effects of mixed polysaccharides,oxalic acid,acetic acid,citric acid,malic acid,mixed organic acids,mixed organic acids+mixed polysaccharides,and S.luteus on the morphology changes of rock particles and the amount of ions dissolved in the culture solution.The SEM image showed that the morphology of all rock particles were changed under different processing conditions,the morphology of the rock particles treated with oxalic acid and mixed organic acid had a more regular morphology,resembling a rectangular parallelepiped shape.The dissolved amount of each ion in the mixed organic acid+mixed extracellular polysaccharide treatment solution and the culture broth of S.luteus was large,the dissolution amount of P⁵⁺(mg/L)were2.543 and 4.693 respectively;the dissolution amount of K⁺(mg/L)were:32 and86.17respectively;the dissolution amount of Al³⁺(mg/L)were 0.284 and 0.431respectively;the dissolution amount of Ca²⁺(mg/L)were:0.181 and 2.133;respectively the dissolution amount of Fe³⁺(mg/L)were:2.333 and 2.553 respectively;the dissolution amount of Si⁴⁺(mg/L)were 35.166 and 39.706 respectively.EDS analysis may had derived a secondary mineral added oxygen and iron from the rock particles treated with oxalic acid and mixed organic acids,which was preliminarily determined to be iron ore.Organic acids and polysaccharides both had certain weathering effects on rocks.The weathering effect of mixed organic acids+mixed polysaccharides on rocks was significantly higher than that of single the role of metabolites,and among the five single test metabolites,oxalic acid had the obvious weathering effect on rock,and the formation of secondary mineral iron ore was closely related to oxalic acid secreted by S.luteus.