重金属阻控菌剂的制备及其减少生菜吸收Cd和Pb的作用

Preparation of bacterial heavy metal-immobilizing agents and their effects on reducing Cd and Pb uptake in lettuce

制备重金属阻控菌剂并研究其减少蔬菜吸收重金属的效果,有望为蔬菜安全生产和修复农田生态环境提供一种有效材料。本试验以具有吸附重金属的植物促生细菌Bacillus megaterium H3为供试菌株,采用单因素试验、Plackett-Burman设计法、最陡爬坡试验和响应面分析法对菌株H3发酵培养基进行优化。选用海泡石(C1)和生物炭(C2)作为载体制备固体菌剂,通过田间小区试验,评价重金属阻控菌剂对意大利生菜(Lactuca sativa L.)的品质、Pb和Cd含量以及土壤特性的影响。结果表明:优化后发酵培养基主成分为糖蜜3.8 g·L^(-1)、大豆粉9.25 g·L^(-1)、碳酸钙9.5 g·L^(-1)时,菌株H3芽孢数提高到5.9×10;CFU·mL^(-1),较初始培养基芽孢数提高了156%。固体菌剂C2保藏6个月后有效活菌数在2.0×10^(8)CFU·g^(-1)以上,生物炭适合作为B.megaterium H3菌剂载体。在受污染农田中,菌株H3发酵液、生物炭和固体菌剂C2均可以提高生菜干质量和Vc含量,减少生菜的Cd和Pb含量,降低土壤有效态Cd和Pb含量,增加土壤脲酶和蔗糖酶活性。其中固体菌剂C2效果好于单一菌液或生物炭处理,具有保障生菜安全生产、修复受污染农田的潜力。

To ensure the safe production of vegetables and improve the ecological environment of farmland, it is necessary to expand the screening of safe and efficient heavy metal immobilization agents. In this study, single-factor experiments, Plackett-Burman design,steepest climbing test, and response surface analysis were used to optimize the spore formation medium of Bacillus megaterium H3. Sepiolite(C1)and biochar(C2)were selected as carriers to promote the survival of Bacillus megaterium H3. Field plot experiments were used to evaluate their effects on the growth and Cd and Pb contents in Italian lettuce(Lactuca sativa L.), and the characteristics of heavy metalcontaminated soils. The results showed that the optimized fermentation medium was molasses 3.8 g·L^(-1), soybean meal 9.25 g·L^(-1), calcium carbonate 9.5 g·L^(-1). The maximum number of spores was 5.9×10^(8)CFU·mL^(-1), which was 156% higher than that in the initial fermentation medium. Biochar was a suitable carrier for the preparation of B. megaterium H3 microbial inoculants. B. megaterium H3 fermentation liquid, biochar, and solid agent C2 could increase the biomass and Vc content in Italian lettuce, reduce the content of Cd and Pb, and reduce the content of available Cd and Pb in the soils, while increasing the activities of urease and invertase. The solid agent C2 was found to be more effective than the B. megaterium H3 fermentation liquid and biochar single treatment. This study confirms that solid agent C2 can be a vital immobilization agent that can be used successfully to remediate heavy metal-polluted soils.