| With the acceleration of urbanization and industrialization,heavy metal contamination of soil has become more serious. It is one of the main ecological and environmental problems, faced today. It directly affects to the stability of regional ecosystems and food safety then affects to the econo- my, especially the sustainable development of agriculture and human health, the extensive attention of the society. To seek the methods to solve this heavy metal pollution of the soil, the adsorption capacity of the microbial screening out from heavy metal contaminated, Hg and Pb can be adsorbed on the screening of microorganisms. In addition, the adsorption mechanism of dominant strains was also studied. The main results are as follows:1. 68 mercury-resistant(100mg/L) fungal strains and 97 lead resistant(1000mg/L) fungal strains and 170 mercury-resistant(100mg/L) bacteria and 66 lead resistant(400mg/L) bacteria were screened in this study.2. The high resistant stains to heavy metals had been screened by incresing the content of heavy metala in culture medium. The results had indicated that there are 23 strains of fungi which could tolerate 3500mg/L for lead, 3 strains of fungi could tolerate 350mg/L for mercury, 3 stra ins of bacteria could tolerate 800mg/L for lead, and 5 strains of bacteria could tolerate 800mg/L for mercury.3.The high resistance strains,were selected to the fermentation test,in addition,to that we have selected some of the other resistance strains for above test. Test results showed that the ⑥ZW15-12,ZW2-5 and ZN14-12 on lead removal rate reached 99.36%±0.12%、99.47%±0.3% and 99.17%±0.1%;the ③ZN17-1 fungi on mercury removal rate reached82.4%±0.40%,③ZT13-4 was as high as 92.00%±0.20%. D7-25 on lead removal rate reached 82.4%±0.2%,④T13-21 on lead removal rate as high as 91.30%±0.3%;W6-10 on the mercury removal efficiency up to 83.3%±0.7%. In addition,the results also showed that the high resistance strains were better than the low strains on the removal of heavy metals.4. The fungal strains were screened,which had high resistance and absorption to heavy metal by combining their morphological,physiological and biochemical data and the phylogenetic tree of r DNA sequences,ZW2-5 and ⑥ZW15-12 were identified as Penicillium Oxalicum,ZN14-12 Penicillium janthinellum,③ZN17-1 Emericellopsis minima,③ZT13-4 Fusarium striatum, ④T13-21 and D7-25 Arthrobacter niigatensis,W6-10 Bacillus cereus.5. In the concentration of 100mg/L lead or 20mg/L mercury,extracellular polymeric protein, sugar and intracellular glutathione of ZW2-5、ZN14-12、③ZT13-4、③ZN17-1 are higher than those without cases of high lead or mercury.The results showed that the adsorption process of dominant bacteria on lead and mercury has surface, adsorption, and intracellular detoxification.6. The optimal conditions of ZW2-5 for Pb(100mg/L) removal rate,when cultured for 9 days, the amount reached to 3ml or 4ml at p H6 or p H7. The optimal conditions of ③ZT13-4(20mg/L) on mercury removal rate,when cultured for 9 days,the amount reached to 4ml at p H7. The best conditions for ④T13-21 on lead(50mg/L) removal rate,when cultured for 8-9 days, the amount reached 3-5ml at p H6-7; the optimum conditions for W6-10 on mercury(50mg/L) removal rate,when cultured for 8-10 days,the amount reached to 1-5ml at p H6-7. |
PDF Full Text Request