Microbe-assisted phytoremediation is of great significance for the remediation of soil contaminated with heavy metals(HMs),and probiotics are beneficial microorganisms that can improve soil structure and fertility and...Microbe-assisted phytoremediation is of great significance for the remediation of soil contaminated with heavy metals(HMs),and probiotics are beneficial microorganisms that can improve soil structure and fertility and promote plant growth.However,there are few studies on probiotics applied to remediate soil contaminated with HMs,and whether probiotics can improve the efficiency of phytoremediation still needs to be further investigated.This study aimed to investigate the effects of two kinds of probiotics,Lactobacillus casei(Lc)and Bacillus licheniformis(Bl),on activating the remediation potential of leaf mustard,Brassica juncea(L.)Czerniak.,for soil contaminated with Cd and Zn using incubation and pot experiments.The results showed that the addition of the two probiotics significantly reduced soil pH by 0.05–0.32 units and improved the available contents of soil HMs(by 15.3%–60.0%and 7.1%–23.8%for Cd and Zn,respectively)in the incubation experiment.After probiotic addition,available Cd and Zn contents in soil treated with 1×10^(9) colony forming units(cfu)mL^(-1) Bl were 1.65-and 1.66-folds of those in the control without probiotic,respectively,in the pot experiment.Meanwhile,soil alkaline phosphatase,urease,and sucrose activities were increased,indicating that soil microbial metabolic activities were also stimulated.Addition of Lc and Bl significantly improved the biomass and chlorophyll contents of leaf mustard.The contents of Cd and Zn in shoots and roots were significantly increased in the treatment with 1×10^(5) cfu mL^(-1) Lc.Furthermore,the activities of plant antioxidant enzymes,including superoxide dismutase,peroxidase,and catalase,were increased,and the content of plant malondialdehyde was reduced,indicating that the resistance of plants to HMs was enhanced.These results indicated that these two kinds of probiotics could enhance the availability of Cd and Zn directly in soil and promote the growth of leaf mustard,thereby increasing the efficiency of phytoremediation for HMs.The study provides a useful reference for probiotic-assisted phytoremediation of soil contaminated with HMs.展开更多
Chlorinated persistent organic pollutants, including polychlorinated biphenyls （PCBs）, represent a particularly serious environmental problem and human health risk worldwide. Leguminous plants and their symbiotic ba...Chlorinated persistent organic pollutants, including polychlorinated biphenyls （PCBs）, represent a particularly serious environmental problem and human health risk worldwide. Leguminous plants and their symbiotic bacteria （rhizobia） are important components of the biogeochemical cycling of nitrogen in both agricultural and natural ecosystems. However, there have been relatively few detailed studies of the remediation of PCB-contaminated soils by legume-rhizobia symbionts. Here we report for the first time evidence of the reductive dechlorination of 2,4,4＇-trichlorobiphenyl （PCB 28） by an alfalfa-rhizobium nitrogen fixing symbiont. Alfalfa （Medicago sativa L.） inoculated with wild-type Sinorhizobiurn meliloti had significantly larger biomass and PCB 28 accumulation than alfalfa inoculated with the nitrogenase negative mutant rhizobium SmY. Dechlorination products of PCB 28, 2,4＇-dichlorobiphenyl （PCB 8）, and the emission of chloride ion （C1-） were also found to decrease significantly in the ineffective nodules infected by the mutant strain SmY. We therefore hypothesize that N2-fixation by the legume-rhizobium symbiont is coupled with the reductive dechlorination of PCBs within the nodules. The combination of these two processes is of great importance to the biogeochemical cycling and bioremediation of organochlorine pollutants in terrestrial ecosystems.展开更多
基金supported by the Science and Technology Overall Innovation Project of Shaanxi Province,China(No.2016 KTCQ03-20)the Scientific Research Foundation Project of Quzhou University,China(No.KYQD006224002).
文摘Microbe-assisted phytoremediation is of great significance for the remediation of soil contaminated with heavy metals(HMs),and probiotics are beneficial microorganisms that can improve soil structure and fertility and promote plant growth.However,there are few studies on probiotics applied to remediate soil contaminated with HMs,and whether probiotics can improve the efficiency of phytoremediation still needs to be further investigated.This study aimed to investigate the effects of two kinds of probiotics,Lactobacillus casei(Lc)and Bacillus licheniformis(Bl),on activating the remediation potential of leaf mustard,Brassica juncea(L.)Czerniak.,for soil contaminated with Cd and Zn using incubation and pot experiments.The results showed that the addition of the two probiotics significantly reduced soil pH by 0.05–0.32 units and improved the available contents of soil HMs(by 15.3%–60.0%and 7.1%–23.8%for Cd and Zn,respectively)in the incubation experiment.After probiotic addition,available Cd and Zn contents in soil treated with 1×10^(9) colony forming units(cfu)mL^(-1) Bl were 1.65-and 1.66-folds of those in the control without probiotic,respectively,in the pot experiment.Meanwhile,soil alkaline phosphatase,urease,and sucrose activities were increased,indicating that soil microbial metabolic activities were also stimulated.Addition of Lc and Bl significantly improved the biomass and chlorophyll contents of leaf mustard.The contents of Cd and Zn in shoots and roots were significantly increased in the treatment with 1×10^(5) cfu mL^(-1) Lc.Furthermore,the activities of plant antioxidant enzymes,including superoxide dismutase,peroxidase,and catalase,were increased,and the content of plant malondialdehyde was reduced,indicating that the resistance of plants to HMs was enhanced.These results indicated that these two kinds of probiotics could enhance the availability of Cd and Zn directly in soil and promote the growth of leaf mustard,thereby increasing the efficiency of phytoremediation for HMs.The study provides a useful reference for probiotic-assisted phytoremediation of soil contaminated with HMs.
基金supported by the National Natural Science Foundation of China(Grant Nos.41201313&41230858)
文摘Chlorinated persistent organic pollutants, including polychlorinated biphenyls （PCBs）, represent a particularly serious environmental problem and human health risk worldwide. Leguminous plants and their symbiotic bacteria （rhizobia） are important components of the biogeochemical cycling of nitrogen in both agricultural and natural ecosystems. However, there have been relatively few detailed studies of the remediation of PCB-contaminated soils by legume-rhizobia symbionts. Here we report for the first time evidence of the reductive dechlorination of 2,4,4＇-trichlorobiphenyl （PCB 28） by an alfalfa-rhizobium nitrogen fixing symbiont. Alfalfa （Medicago sativa L.） inoculated with wild-type Sinorhizobiurn meliloti had significantly larger biomass and PCB 28 accumulation than alfalfa inoculated with the nitrogenase negative mutant rhizobium SmY. Dechlorination products of PCB 28, 2,4＇-dichlorobiphenyl （PCB 8）, and the emission of chloride ion （C1-） were also found to decrease significantly in the ineffective nodules infected by the mutant strain SmY. We therefore hypothesize that N2-fixation by the legume-rhizobium symbiont is coupled with the reductive dechlorination of PCBs within the nodules. The combination of these two processes is of great importance to the biogeochemical cycling and bioremediation of organochlorine pollutants in terrestrial ecosystems.
