| With the rapid development of China’s economy,the problem of soil lead pollution has become increasingly prominent.The heavy metal lead in the soil will enter the human body along with the food chain,endangering human health.Therefore,there is an urgent need to repair the soil heavy metal problem and improve the living environment for humans.Bioremediation techniques in soil remediation have attracted a lot of attention from scholars at home and abroad due to their advantages of low cost and no secondary contamination,and they have achieved good research results.Most of the current research has focused on the remediation of heavy metals from turf.This article focuses on Festuca arundinacea Schreb,Eremochloa opiuroides(Munro)Hack,and root microbiota to study the effect of root microbiota on the remediation of soil lead pollution by Festuca arundinacea Schreb and Eremochloa opiuroides(Munro)Hack.The metabolic activity and metabolites of microorganisms can facilitate the absorption of heavy metals by plants,reduce the toxic effects of heavy metals on plants,and provide a theoretical and experimental basis for the combination of turfgrass and microbial remediation.The main findings are as follows:(1)F.arundinacea Schreb and E.ophiuroides(Munro)Hack were selected from lawn grass for seed germination experiment.When the lead concentration was1.2,2.4 and 4.8 g/L,the germination rate and plant height of F.arundinacea Schreb and E.ophiuroides(Munro)Hack reached the maximum at a lead the concentration of1.2 g/L,With the increase of lead concentration,the relative germination rate,germination potential and germination index of F.arundinacea Schreb and E.ophiuroides(Munro)Hack showed a downward trend,which showed that high concentration of lead inhibited the germination of the two turfgrasses.The higher the lead concentration,the stronger the inhibition,and the tolerance of E.ophiuroides(Munro)Hack to lead was much lower than that of F.arundinacea Schreb seeds.(2)In this paper,two lead resistant strains,F11 and F23,have been screened and isolated from lead-zinc mine-contaminated soil.Morphological observations and16 Sr DNA sequence analysis were performed on them,and the adsorption mechanisms of the two strains were investigated.When the lead concentration is 250 mg/kg,the removal rates of strain F11 and strain F23 reach to 60.47% and 74.15%,respectively,through morphological observation and 16 Sr DNA sequence analysis,the similarity between strain F11 and Pseudomonas sp was 99%,the similarity between strain F23 and Cellulosimicrobium is 99%.Analysis of the growth curves of the two lead-resistant strains showed that the bacterial population of the two strains did not increase significantly before 0 to 8 h,as they had just been inoculated into the LB medium and needed to adapt to the new environment.It was a period of stunted growth.The bacteria start to grow slowly after 8-10 h.After more than 10 hours of incubation,the bacteria grow rapidly and enter a logarithmic growth period.(3)After 40 days of cultivation of F.arundinacea Schreb and E.ophiuroides(Munro)Hack,when the soil lead concentration is 3500 mg/kg,the enrichment coefficients of F.arundinacea Schreb and E.ophiuroides(Munro)Hack reach 1.61 and 1.39,indicating that the two turf grasses have good enrichment effect,and the low concentration of lead can promote the chlorophyll,catalase,biomass,plant height and root length of plants.As the lead concentration increases,so does the amount of metaldehyde,suggesting that the plant mitigates the harm caused by lead stress through its own various reactions.(4)Under stress from lead,both strains F11 and F23 are effective in improving plant repair efficiency,and access to both strains can significantly increase plant tolerance to lead;Reduce the amount of malondialdehyde in the plant;Increasing catalase activity and concentration of soluble sugars in plants;Promote microbial diversity in plant roots,improve plant biomass,and promote accumulation of heavy metals in plants. |
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