Biological removal of cadmium in rice by lactobacillus and its mechanism
School of Food Science and Technology,Jiangnan University,Wuxi,214122
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.