| This work aims at the key techniques of rapid,low-cost processing and disposal of a large number of hyper-enriched plant bodies produced after phytoremediation of polluted environment.Optimization of enzyme production and complex formulation of stains were conducted with lignocellulose-degrading bacteria C1,C3,C5,C11 which were obtained from the previous screening and C16 which was stored in the laboratory environment for the preparation of the microbial complex bacteria agent.The basic research on microbial volume reduction and weight reduction of hyper-enriched plant was carried out using Indian mustard and other super-enriched plants as experimental materials.Changes in the parameters such as medium volume,activities of cellulose,hemicellulose,lignin,and cellulase production by simulating volume reduction and weight reduction of uranium(U)-rich plants were investigated.These results can provide theoretical and technical support for the research on the technology of microbial volume reduction and weight reduction of hyper-enriched plants.The findings were as follows:(1)The optimal cellulase production of strain C1 was achieved under the following conditions: peptone as nitrogen source,culture temperature of 39 ?,inoculum volume of 3 m L,initial p H of 8.The carboxymethylcellulose activity(CMCA)and filter paper activity(FPA)on Day 4 and Day 5 were measured as: 166.27 IU and 145.45 IU.The optimal cellulase-producing conditions for strain C3 were as follows: peptone as nitrogen source,culture temperature of 37 ?,inoculum volume of 3 m L,initial p H of 7.FPA and CMCA measured on Day 4 and Day 5 were as follows: 225.62 IU and 261.32 IU,respectively.The optimal cellulase-producing conditions for strain C5 were as follows: peptone as nitrogen source,culture temperature of 39 ?,inoculum volume of 3m L,initial p H of 7,and FPA and CMCA measured on Day 3 and Day 5 were 218.43 IU and 219.35 IU,respectively.The optimal cellulase-producing conditions of strain C11 were as follows: peptone as nitrogen source,culture temperature of 40 ?,inoculum volume of 3 m L,initial p H of 8,and the CMCA and FPA measured on Day 3 and Day 5 were 156.87 IU and 172.53 IU,respectively.The optimal cellulase-producing conditions of strain C16 were as follows: peptone as nitrogen source,culture temperature of 30 ?,inoculation amount of 3 m L,initial p H of 5.5,and FPA and CMCA measured on Day 5 were: 237.24 IU and 266.68 IU,respectively.When the strain ratio was C1: C3: C5: C11: C16 = 1: 3: 1: 3: 3,the CMCA and FPA of the composite bacteria reached the maximum values of 657.33 IU and 645.49 IU,respectively.(2)The volume reduction rate of the hyper-enriched plants treated with the microbial complex bacteria agent reached 96 %,which was 23 % higher than that of the control without the microbial complex bacteria treatment.The cellulose degradation rate of the hyper-enriched plants was 80.75 %,which was 27.35 % higher than the control.The degradation rates of hemicellulose and lignin were 69.06 % and 28.59 %,respectively,which were correspondingly 14.75 % and 5.49 % higher than the control.(3)The mechanism of microbial volume reduction and weight reduction of hyper-enriched plant is that the microorganisms use the organic matters and other nutrients in the hyper-enriched plant body to grow and reproduce,releasing a large amount of heat.The lignocellulose in the hyper-enriched plant body is degraded by cellulase production to reduce the volume,thereby achieving the purpose of rapid reduction in the volume and weight of the hyper-enriched plant body using microorganisms.Microbial complex bacteria agents in different treatment concentrations have different volume reduction effects on hyper-enriched plants.When the concentration of the microbial complex bacteria agent was 5 %,the volume reduction rate of the hyper-enriched plants was 76.12 %,which was 37.61 % higher than the control,and the degradation rates of hemicellulose,cellulose and lignin were 70.07 %,74.37 % and 35.59 %,respectively,which were correspondingly 32.18 %,29.29 % and 4.31 % higher than the control group.(4)Adding microbial complex bacteria agent can effectively reduce the volume and weight of U-enriched plants.Low-concentration U-enriched plants have a better volume reduction effect.When the U-enriched plant concentration exceeds 200 mg/kg,the volume reduction effect begins to decrease.When the U enrichment treatment was 100 mg/kg,the volume reduction rate of the hyper-enriched plants was 81.33 %,which increased by 6.05 % compared with the control,and the degradation rates of hemicellulose,cellulose and lignin were 75.59 %,76.19% and 30.97 %,respectively,which correspondingly increased by 5.07 %,7.44 % and 2.66 %,respectively,compared with the control. |
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