Mechanism Of Cadmium And Copper Stress Affecting The Growth Ganoderma Lucidum Mycelium

Heavy metals are important environmental factors affecting the growth and metabolism of edible and medicinal fungi.Excessive heavy metals affect the growth of the edible and medicinal fungi themselves,and affect the synthesis of important active substances of edible and medicinal fungi.As a medicinal and medicinal fungi with a long history,Ganoderma lucidum is deeply affected by heavy metals during the cultivation process.The molecular mechanism of the effects of heavy metals on G.lucidum is still unclear,but its toxicity is closely related to the antioxidant mechanism.Therefore,heavy metals are studied.The effects on the growth of G.lucidum and the antioxidant response mechanism might provide a theoretical basis for further revealing the mechanism of heavy metal toxicity,and provide a theoretical basis for the control of heavy metal pollution in the cultivation of edible and medicinal fungi.Cd and Cu are heavy metal elements in contaminated soil,which seriously affect the growth of medicinal medicinal fungi and human health.In this paper,G.lucidum mycelium is used as research object,and Cd and Cu heavy metals are used to culture them at different concentrations.The effect of Cd and Cu on the growth of G.lucidum and the antioxidant response mechanism of mycelium.Method:G.lucidum mycelium was cultured in different concentrations of Cd and Cu medium to observe the growth and biomass changes of G.lucidum colonies at different concentrations.The ROS levels,MDA content and antibiotics in mycelium were determined by different Cd and Cu treatment concentrations.The expression of oxidase-related genes and antioxidant enzyme activities were analyzed.The effects of Cd and Cu on the physiological characteristics and related gene expression of G.lucidum mycelium were analyzed.The effect of Cd and Cu on GPX activity was analyzed in vitro by expressing GPX protein.The contents of protein,polysaccharide and total triterpenoids in mycelium were analyzed.The effects of different concentrations of Cd and Cu on the important metabolites of mycelium were analyzed.The expression levels of key enzymes Sqs and Osc of G.lucidum triterpenoids were analyzed,and Cd and Cu were analyzed.The effect of stress on the secondary metabolism of G.lucidum mycelium.Results:1.Both cadmium and copper promoted mycelial growth at low concentrations,inhibited growth at high concentrations;cadmium concentration more than 4 mg/L,and copper concentration more than 60 mg/L liter inhibited mycelial growth.2.With the increase of cadmium and copper concentration,the intracellular ROS level and MDA content of G.lucidum mycelia increased.When cadmium treatment concentration reached 4 mg/L,ROS level and MDA content increased significantly.When the concentration reached 20mg/L,the MDA content of mycelium increased significantly.When it reached 60mg/L,the ROS of mycelium increased significantly.The expression of NADPH oxidase was activated after Cd treatment,the enzyme activity increased,and cadmium treatment When the concentration reached 1 mg/Liter,the activity of APX was significantly increased,and the activity of GPX was significantly decreased.When the concentration of Cd and Cu were 1 mg/L and 10 mg/L,the CAT and SOD enzyme activity increased significantly and reached the peak.When the concentration of Cu reached 20mg/L,the activities of SOD,CAT,APX and GPX increased significantly.When the concentration of copper reached 40 mg/Liter,the activities of SOD,CAT,APX and GPX peaked,with the treatment concentration.Continued increase continues to decline.Exogenous ROS scavengers NAC,VC and NADPH oxidase(NOX)inhibitors can reduce the accumulation of intracellular ROS in G.lucidum.3.Cd stress significantly up-regulated the expression levels of antioxidant enzymes Sod1,Sod4,Cat,Gpx and Apx.Cu stress significantly up-regulated the expression levels of Sod1,Sod4,Cat,Gpx and Apx.The expression and purifiCation of GPX protein were verified in vitro.Cd10mg/L significantly inhibited GPX activity,while Cu ion had no effect on GPX.4.With the increase of Cd and Cu treatment concentration,the total protein content of G.lucidum increased first and then decreased.When the concentration of Cd treatment exceeded 1 mg/L,the total protein content and total triterpenoid yield decreased with the concentration.When the treatment concentration of Cd reached 10mg/L,the total triterpenoid yield was significantly lower than that of the control group.When the Cd reached 40mg/L,the total protein content was significantly lower than that of the control group.When the Cu treatment concentration reached 40mg/L,the G.lucidum mycelium polysaccharide,total protein and total triterpenoids were the highest,and the content decreased with the increase of concentration.The total triterpenoid yield and protein content were significantly lower than that of the control group when the concentration of Cu was 100 mg/L.Conclusion:When the concentration of Cd and Cu ions exceeded 1 mg/L and 40 mg/L,the activity of antioxidant enzymes increased,the growth of mycelium,the synthesis of polysaccharide,and total proteins were inhibited.And the synthesis of metabolites had a greater impact.When Cd was more than 4mg/L,the activity of NOX was activated,and the expression of antioxidant-related genes Sod,Cat,Apx and Gpx was promoted,but the activity of GPX was inhibited,and the activities of antioxidant enzymes SOD and CAT were decreased.The activity of APX increased,the level of intracellular ROS increased,the membrane oxidative damage increased,the mycelial growth was inhibited,the total protein and total triterpenoid content in hyphae decreased.When Cu stress was greater than 60 mg/L,ROS level increased,but NOX enzyme no effect,the expression of Sod,Apx and Gpx genes was up-regulated,APX activity increased,SOD,CAT and GPX activities showed a downward trend,membrane oxidative damage was aggravated,and mycelial growth was inhibited.In summary,there are differences in the mechanism of Cd and Cu affecting mycelial growth.Cd ions may mainly inhibit the activity of GPX enzymes,causing peroxide accumulation,thereby activating NOX enzyme activity and increasing ROS levels,thereby causing membrane damage MDA accumulation,and affecting growth and accumulation of metabolites.However,copper ions have no significant effect on GPX,and have a greater influence on CAT enzyme.Therefore,different strategies should be adopted in the production process according to the differences in growth mechanisms and metabolite accumulation mechanisms of heavy metals.