Study On The Antifungal Mechanism Of Active Ingredients From Konjac Fly Powder And Decay Resistance Of Treated Poplar

Wood preservation is a method to enhance the durability of wood.It is mainly treated by physical or chemical means to protect it from decay fungi,insects,marine drilling animals,etc.Human pay more attention to environmental protection and the use of chemical products has promoted the development of natural and environmentally friendly wood preservatives.Konjac flying powder is a by-product of processing Konjac(Amorphophallus konjac K.Koch),a cash crop in Shanxi,Ningxia,Gansu,Sichuan and other places.Previous studies have shown that it has antibacterial activity against wood decay fungi.In this study,the anti-fungal activities of the active ingredients of konjac flying powder against white rot fungi[Coriolus versicolor(L.)Quel.]and brown rot fungi[Gloephyllum trabeum(Pers.)Murrill.].Silica gel column chromatography and ultra-performance liquid chromatography-mass spectrometry(UPLC-MS)was be used to identify the composition of compounds that inhibit the active of wood decay fungi in Konjac flying powder extract.The antifungal mechanism of wood decaying fungi was analyzed from mycelial morphology,cell membrane permeability,respiratory metabolism,and cellulose hemicellulose and lignin enzyme activity.The performance of poplar treated by Konjac flying powder extract was evaluated from corrosion resistance,color,dimensional stability,and flexural strength.A comprehensive evaluation of the potential of Konjac flying powder extract as a wood preservative provides a theoretical basis for the use of Konjac flying powder.The main findings obtained are as follows.(1)Konjac flying powder extract has anti-fungal activity.The Coriolus versicolor and Gloephyllum trabeum treated with 40 mg/ml extract no longer grow.Konjac flying powder ethyl acetate and chloroform extract have the strongest anti-fungal activity.After separation by silica gel column chromatography,active components were screened out.UPLC-MS identification revealed the antifungal activity of Konjac flying powder.Ingredients are mainly composed of fatty acids,organic acids and plant essential oils.The anti-fungal activity test verified that organic acids(salicylic acid)and plant essential oil compounds(2,4,6-trichlorophenol,vanillin,and cinnamaldehyde)have strong activity against wood decay fungi.(2)The antifungal effects of konjac powder extract on brown rot fungi-Gloephyllum trabeum and white rot fungi-Coriolus versicolor were as follows:Konjac flying powder extract can inhibit the normal life activities of wood decay fungi by inhibiting the cellulase,hemicellulase activity of this two wood decay fungi and the ligninase activity of Coriolus versicolor;inhibiting the respiratory metabolism of wood decay fungi,especially the EMP pathway;causing mycelium to be broken and deformed.(3)The antifungal effects of organic acid compound(salicylic acid)on Gloephyllum trabeum and Coriolus versicolor were as follows:Salicylic acid can inhibit the normal life activities of wood decaying fungi by inhibiting the hemicellulase activity of two wood decay fungi and the ligninase activity of Coriolus versicolor;It can enhance the cell membrane permeability of this two wood decay fungi to to cause nucleic acid spillage.(4)Plant essential oil compounds 2,4,6-trichlorophenol,vanillin and cinnamaldehyde have relatively strong fungistatic effects of two wood decay fungi.The antifungal effects of2,4,6-trichlorophenol on two wood decay fungi were as follows:2,4,6-trichlorophenol can inhibit the normal life activities of wood decay fungi by inhibiting the cellulase,hemicellulase activity of two wood decay fungi and the ligninase activity of Coriolus versicolor;It can inhibit the respiratory metabolism of wood decay fungi,especially the EMP pathway and cause mycelium to be broken and deformed.The antifungal effects of vanillin and cinnamaldehyde on two wood decay fungi were as follows:Vanillin and Cinnamaldehyde can inhibit the normal life activities of wood decay fungi by inhibiting the hemicellulase activity of two wood decay fungi and the ligninase activity of Coriolus versicolor and cause its hyphae to swell and deform;They can enhance the cell membrane permeability of this two wood decay fungi to to cause protein and nucleic acid spillage.Cinnamaldehyde can also inhibit the EMP pathway of aerobic respiration of the wood decay fungi.(5)The corrosion resistance test of Konjac flying powder extract treated poplar showed that Konjac flying powder extract had stronger anti-fungal effect on the brown rot fungi-Gloephyllum trabeum than white rot fungi-Coriolus versicolor.When the concentration of Konjac flying powder extract reached 160 mg/ml,the mass loss of treated poplar was 33.5%(untreated poplar was 44.7%)and 11.9%(untreated poplar was 39.4%).The stearolic acid,salicylic acid and cinnamaldehyde treated poplar resistance test showed that only 30 mg/ml salicylic acid and cinnamaldehyde have better fungistatic effect on two wood fungi.The mass loss of poplar treated with salicylic acid and cinnamaldehyde after 5weeks of exposure to the environment of Coriolus versicolor and Gloephyllum trabeum was less than 5%(The mass loss of untreated poplar was 38.1±5.5%and 27.5±4.7%,respectively).That indicated that salicylic acid and cinnamaldehyde treatment improve the corrosion resistance of poplar.(6)The physical properties test of treated poplar from Konjac flying powder extract showed that Konjac flying powder extract impregnated poplar weight gain rate after a slight decrease,the weight gain rate reached a maximum of 21.4%and the volume increase rate reached 6.9%at 130 mg/ml.The?E~*of poplar before and after the impregnation was 23.The color of the treated poplar changed greatly,becoming darker and yellowish blue.The dimensional stability of treated poplar is weakened,and the dimensional stability is enhanced at 160 mg/ml.The elastic modulus,static bending strength,and maximum load of treated poplar were higher than those of the control group and all except the elastic modulus increased with increasing concentration.When it reaches 130 mg/ml,the elastic modulus of the treated poplar is the largest;reaching 10193.1 MPa(untreated poplar is 8324.2 MPa).At160 mg/ml,the static bending strength and the maximum load are the largest,reaching 110.7MPa(untreated poplar is 94.0 MPa)and 2515.8 N(untreated poplar is 2089.9 N).