| Coal gangue is one of the largest industrial solid wastes in China.Its disorderly stacking encroaches on land and pollutes water and soil,causing a series of ecological and environmental problems to be solved urgently.Therefore,the ecological restoration and management of gangue dump is imminent.Microbial-phytoremediation technology has received extensive attention in mine environmental management because of its advantages of high efficiency,economy,cleanliness,and the ability to reduce the harm of pollutants to human health.In this study,the waste coal gangue was selected as the research object,and the microorganisms with excellent phosphorus-resolving effect were screened and used as the test strains.As a functional microorganism,it is used in the "coal ganguemicroorganism-plant" intercropping system of no-guest soil,aiming to effectively improve the problems of low survival rate,poor stress resistance,and poor growth conditions of gangue dump vegetation.It has important practical significance for the ecological restoration and management of gangue dumps.The results were as follows:(1)The surface contaminated soil around a mine was collected,and two microorganisms with relatively good phosphorus removal efficiency were finally selected through enrichment,domestication,separation and screening.The colonies and cell morphology were observed,physiological and biochemical identification,cell molecular biology identification,bacterial 16 Sr DNA identification,and phylogenetic tree construction were conducted to identify B1 as Bacillus megaterium strain B1 and B2 as Bacillus licheniformis strain B2.The growth curves of the two strains were measured,which showed that the B1 and B2 strains grew rapidly and could be used in subsequent experiments.(2)Inoculation of microorganisms could significantly increase the nutrient content of coal gangue and effectively reduce its p H.Under the conditions of inoculation amount of150 m L,that is,the solid-liquid ratio of 1:3,culture for 6 days,30 ℃ and initial p H of the system = 7.0,the contents of available phosphorus,available potassium and available nitrogen in coal gangue were significantly increased by 152.92%,101.03% and 196.90%,respectively,and p H was reduced by 0.41 units.The phosphate-solubilizing bacteria were mainly adsorbed on the surface of coal gangue,and the bacterial adsorption capacity was larger at about 420 min.ζ potential results showed that,the potential difference between B1 strain and coal gangue sample was higher than that of B2 strain under the premise of initial p H=7.0 of the system,and it could be more effectively adsorbed on the surface of coal gangue.FT-IR analysis showed that the stability of B2 strain was stronger than that of B1 strain at the cell level,so the adsorption capacity of B2 strain was lower than that of B1 strain.Therefore,compared with B2 strain,inoculation of B1 strain,i.e.,Bacillus megaterium,could improve the nutrient content of coal gangue more effectively.(3)Inoculation of Bacillus megaterium and intercropping both promoted the absorption of trace elements by plants,especially Fe elements in the underground part,and the effect of the intercropping system on the absorption of trace elements was better than that of the monocropping system as a whole.The inoculation of Bacillus megaterium can promote the growth of the plants,with the plant height increased by 14.4%–31.4% and the dry weight of the aboveground and underground parts increased by 92.0%–138% and74%–124% respectively as compared with that of the monocropping.Compared with monocropping,intercropping improved the ability of plant leaves to resist stress.After inoculation with Bacillus megaterium,the activities of SOD,POD and CAT were increased,the free radical scavenging ability of Medicago sativa leaves was enhanced,the MDA content was decreased,and the stress resistance was enhanced.IZMJ treatment had a significant effect on improving the resistance to stress of Cajanus cajan,and the MDA content was lower than that of Medicago sativa and reached the lowest.Compared with monocropping,intercropping helped to reduce the extent of leaf damage in Leucaena leucocephala.(4)Inoculation of Bacillus megaterium and intercropping were both conducive to improving the nutrient content of coal gangue,in which the contents of available potassium and available phosphorus were increased by 16.49% and 33.11%,and p H was decreased by 0.49 units.Urease,phosphatase,sucrase,and FDA hydrolase activities were all increased,while catalase activity was inhibited.The system of "coal ganguemicroorganism-plant" can be initially established.Intercropping and inoculation of Bacillus megaterium did not change the dominant bacterial phylum of coal gangue.Plants can change the bacterial commumity structure by selecting beneficial flora such as Bacillus,to reduce the stress of poor site environment of coal gangue and barren nutrients on the plants,and to improve the stress resistance and survival rate of the plants. |
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