枯草芽孢杆菌与巨大芽孢杆菌对土壤有效态Cd的影响研究

Effect of Bacillus subtilis and Bacillus megaterium on Soil Available Cd

将枯草芽孢杆菌和巨大芽孢杆菌接种于Cd污染土壤中,研究了短期与长期恒温培养条件下枯草芽孢杆菌和巨大芽孢杆菌对土壤有效态Cd含量的影响.短期试验结果表明,枯草芽孢杆菌可降低土壤有效态Cd含量的5.07％～42.63％,在培养72 h时,接种25 ml枯草芽孢杆菌处理的有效态Cd含量较对照组显著降低了42.63％;巨大芽孢杆菌可活化土壤中的Cd,在培养48 h时,接种5 ml巨大芽孢杆菌的处理土壤有效态Cd含量较对照组显著增加了24.58％.长期培养试验结果表明,接种枯草芽孢杆菌可降低土壤中有效态Cd含量,且随着培养时间的延长,钝化效果更为显著,有效态Cd的含量与土壤pH值呈现显著负相关关系,r=0.325（P＜0.05）;长期培养条件下,接种巨大芽孢杆菌可降低土壤pH,且在培养30 d时接种5 ml巨大芽孢杆菌显著增加了土壤有效态Cd含量.综上所述,枯草芽孢杆菌可以钝化土壤Cd,而巨大芽孢杆菌对土壤Cd有一定的活化作用.

In this study,Bacillus subtilis and Bacillus megaterium were inoculated into Cd-contaminated soil in order to investigate the impact of Bacillus subtilis and Bacillus megaterium on soil available Cd under short-term and long-term incubations.The results of short-term experiment showed that soil available Cd decreased by 5.07% ～42.63% after inoculating Bacillus subtilis.The available Cd in the soil dropped significantly by 42.63%after inoculating 25 ml Bacillus subtilis solution when bacteria were cultivated for 72 h,compared with that in the treatment without inoculation.However,Cd was activated after inoculating Bacillus megaterium,and compared with that in control treatment,soil available Cd increased significantly by 24.58% after inoculated 5ml Bacillus megaterium solution when bacteria were cultivated for 48 h.The results of long-term test indicated that inoculation of Bacillus subtilis could reduce the content of Cd in the soil and the improvement of inactivation of Cd was increased with the extension of the incubation time.A negative correlation was found between soil available Cd and pH value（r=-0.325,P〈0.05）.Under the condition of long-term culture,soil pH decreased after inoculating Bacillus megaterium,and the available Cd in soil increased significantly after inoculating 5 ml Bacillus megaterium solution when bacteria were cultivated for 30 d.In conclusion,Bacillus subtilis can inactivate Cd in soil,while Bacillus megateriumcan activate Cd in soil.