Cadmium,a highly toxic heavy metal affecting food crops like soybean,not only inhibits plant growth and develop-ment but also damages the photosynthetic system,leading to reduced photosynthesis rates.Current cadmium remediation tech-nologies primarily focus on the application of plant hormones and alteration of planting patterns,while the interaction between microorganisms and plants remains underexplored.This study aims to explore the remediation potential of compound white rot fungi in addressing cadmium pollution and the practical application value of immobilization technology.Four types of white rot fungi and Glycine max(Linn.)Merr.were used to prepare solid bacterial agents and set up a soil cultivation method for soybeans.We simulated cadmium-contaminated soil concentrations of 0,50,and 100 mg L-1.Three treatments were conducted for each concentration:a control group(CK)with no treatment,an experimental group with free strains(EG1),and an experimental group with solid agents(EG2).We examined the effects of mixed fermentation and immobilization technology on the strains'adsorption efficiency and established the correlation between cadmium toxicity,immobilized microspheres,and soybean plants.The re-sults indicate that,except for Phanerochaete chrysosporium,the other three strains demonstrated good compatibility.A mixed group of bacterial strains containing Pleurotus sajor-caju and Coriolus versicolor in a 1:1 ratio achieved an adsorption rate of 87.33％in cadmium-contaminated solutions at a concentration of 50 mg L-1.To prolong the duration and improve the adsorption effect of the mixed strain,PVA mixed pellets with a sodium alginate(SA)concentration of 10 g L-1,biochar mass concentration of 15 g L-1,and bacterial content of 2％achieved a degradation rate of(95.12±1.68)％within 96 hours after adding appropriate additives.Introducing immobilized mixed bacteria into simulated cadmium-contaminated soil inhibited the growth and photosyn-thetic indices of soybeans.The maximum decrease in Fo was 42.5％,and the maximum increase in Fv/Fm was 17.2％.After 14 days,the soybean antioxidant system was enhanced,with the highest activities of SOD,POD,and CAT being 27.34％,12.41％,and 13.58％,respectively,in the CK group.Additionally,there was an increase in proline content and a decrease in malondial-dehyde content,indicating enhanced plant resistance.In conclusion,cadmium stress suppresses the photochemical reaction center Ⅱ in plants'photosystems.The immobilization of mixed strains results in higher adsorption efficiency compared to sin-gle or free states.Applying a reliable bacterial agent enables soybeans to effectively trigger their light protection mechanism,produce osmoregulatory substances,and activate the antioxidant system,thus maintaining a stable redox environment and coping with cadmium stress.
关键词
白腐真菌/混菌发酵/固定化技术/镉污染土壤
Key words
white rot fungi/mixed fermentation/immobilization technology/cadmium-contaminated soil
维普
万方数据