乳酸菌对稻米中镉的生物减除及其机理研究
首发时间:2018-02-12
摘要:稻米镉污染一直是农业面临的重大挑战,每年因镉超标而丢弃的稻米造成了大量的经济损失。本研究以10株植物乳杆菌为研究对象,首先评价菌株之间产酸能力和镉吸附能力的差异,后通过发酵实验,以镉去除率和镉分布情况作为指标,初步说明发酵去除大米中镉的原理。在对发酵条件进行优化后深入研究镉的溶出动力学及镉结合态的变化规律。 结果表明,菌株发酵组发酵液pH大幅降低,镉在发酵大米、发酵液上清和菌泥中的分布显示,菌泥镉含量显著高于发酵液上清和大米镉含量,证实了菌株的产酸作用和镉吸附作用在镉去除过程中均起到主要作用,10株菌中,以植物乳杆菌CCFM8610的镉去除率最高,去除率可达到80%以上。优化条件为在料液比1:1.5、接菌量1%、37℃发酵24h,发酵结束后水洗3次,镉去除率可达到89.7%。SDS-PAGE电泳图显示镉结合蛋白在发酵过程中发生了变化,分子量为13KDa的镉结合态最为稳定。大米中的镉主要与谷蛋白结合,且谷蛋白含量的减少为大米中镉含量的减少提供了最大的贡献。
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Biological removal of cadmium in rice by lactobacillus and its mechanism
Abstract:Cadmium pollution on rice has been a major challenge for the agriculture and the rice discarded due to cadmium pollution cause a large number of economic losses every year. 10 plant lactobacillus were chosen as the research object in this study. The differences of cadmium adsorption ability and capacity of producing acid were evaluated firstly. Fermentation experiment was did since the removal rate of cadmium and the cadmium distribution was set as indicators to explain the principle of the loss of cadmium in rice. The dissolution kinetics of cadmium and the cadmium binding state were studied after the fermentation condition was optimized. Results show that the fermented liquid of fermented group has a much lower pH and the distribution of cadmium in the fermented rice ,fermented liquid and mud shows that the cadmium content in mud is significantly higher than and cadmium content in rice and fermented liquid which confirmed that capacity of producing acid and cadmium adsorption ability of strains play a major role in the process of remove of cadmium. The cadmium removal rate of lactobacillus plantarum CCFM8610 was highest inthe selected strains and the removal rate could reach more than 80%. It is concluded that when the material-liquid ratio was 1:1. 5, the inoculation amount was 1%, fermented at 37 ℃for 24 h and wash 3 times at the end of the fermentation the cadmium removal rate could reach 89.7%.SDS-PAGE showedthat cadmium binding protein has changed during fermentation and the cadmium combination state with molecular weight of 13 kda is the most stable. Results showed that cadmium in rice is mainly combined with glutelin and the loss of glutelin provides the most contribution for the loss of cadmium in rice.
Keywords: Rice Cadmium LAB biological remove mechanism
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