铅胁迫下接种AM真菌对龙葵根际土壤微生物群落代谢特征的影响

Effect of arbuscular mycorrhizal fungi on metabolic characteristics of microbial community in Solanum nigrum rhizosphere soil with lead stress

为从微生态角度探索接种AM真菌对铅污染根际土壤微生物群落代谢特征的影响,以摩西管柄囊霉(Funneliformis mosseae)和幼套近明囊霉(Claroideoglomus etunicatum)为接种菌剂,在温室盆栽条件下以Pb4+含量为0 mg·kg-1、200 mg·kg-1、400 mg·kg-1和800 mg·kg-1土壤种植龙葵(Solanum nigrum)10周后采集根际土壤,采用Biolog微平板法测定龙葵根际土壤微生物群落的代谢变化。结果表明:1)微生物平均代谢活性(AWCD)随铅浓度增加呈降—升—降趋势;接种AM真菌显著提高了铅胁迫下根际土壤微生物的AWCD值,仅中浓度(400 mg·kg-1)下未达显著差异。2)中浓度铅处理能显著提高根际土壤微生物对糖类及其衍生物、氨基酸类、脂肪酸和脂类及代谢产物类四大类碳源底物利用能力;接种AM真菌,高浓度(800 mg·kg-1)铅处理显著提高了根际土壤微生物对氨基酸类底物的利用能力。3)铅胁迫下接种AM真菌提高了根际土壤微生物多样性指数,在中浓度下丰富度指数、Shannon-Wiener多样性指数、Simpson优势度指数均达显著水平。4)主成分分析显示,代谢产物类在PC1和PC2中种类最多,分别为6种和4种;糖类及其衍生物在PC3中种类最多(5种)。5)在铅胁迫和接种AM真菌共同作用下,微生物碳源利用主要受铅浓度调节,并且二者对微生物碳源利用具有显著交互效应。综上可知,接种AM真菌能够提高铅胁迫下龙葵根际土壤微生物多样性指数,增强根际土壤微生物对碳源底物的利用能力。该研究为进一步探究AM真菌强化植物联合修复技术提供了依据。

Pot experiments were conducted to explore the effect of arbuscular mycorrhiza(AM)fungi on the characteristics and differences in rhizosphere soils of Solanum nigrum under different levels of lead stress[0 mg·kg-1(CK),200 mg·kg-1,400 mg·kg-1,800 mg·kg-1).To this end,S.nigrum was inoculated with Funneliformis mosseae and Claroideoglomus etunicatum,and the resulting rhizosphere soils collected after 10 weeks of growth under 16 h/8 h,28℃/20℃with 12 000 Lux light intensity in a greenhouse.The characteristics and differences in carbon metabolic profiles of microbes were evaluated using the Biolog-ECO micro-plate method.The results showed that:1)the average metabolic activity of microorganisms,described by average well color development(AWCD),decreased-increased-decreased with increasing lead stress.Inoculation with AM fungi improved AWCD significantly under lead stresses,except for 400 mg·kg-1 Pb4+.2)The ability of soil microbes to utilize the four types of carbon substrates(carbohydrate and derivatives,fatty acid and lipids,amino acids,and metabolites)was higher under 400 mg·kg-1 Pb4+than under low(200 mg·kg-1)and high(800 mg·kg-1)stresses of Pb4+.Inoculation with AM fungi significantly improved the ability of soil microbes to utilize amino acid substrates under high lead concentration.3)Lead stress reduced McIntosh evenness index of rhizosphere soil microbial community,but had no significant impact on richness index,Shannon-Wiener diversity index and Simpson index.Inoculation with AM fungi increased microbial diversity index under lead treatment,and had significant effects on Species richness index,Shannon-Wiener diversity index and Simpson dominance index at medium stress.4)Under the same Pb4+stress,inoculation of AM fungi enhanced metabolic capacity of soil microorganisms for the four major carbon sources,but only had significant effect on amino acids.Principal component analysis showed that metabolites were the most abundant in PC1 and PC2,with respective values of 6 and 4.Sugar was the most abundant in PC3.5)Under combined effects of lead stress and AM fungi,microbial carbon source utilization was mainly regulated by lead concentration,both had significant interaction effects on microbial carbon source utilization.In conclusion,inoculation with AM fungi increased microbial diversity index of rhizosphere soils of S.nigrum under lead stress,and enhanced utilization of carbon source substrate by rhizosphere soil microbes.This study provided theoretical basis for the application of AM fungi which could strengthen the use of phytoremediation technology in soil remediation for heavy metal pollution.