Preparation Of Mineral-sourced Humic Acid Compound Microbial Agent And Its Biological Effect

The clean development and utilization of coal is an effective measure to achieve environmental improvement,and it is also in line with the sustainable development strategy of China,promoting the transformation and upgrading of China’s energy industry,and realizing the high value-added utilization of coal.Coal biotransformation is a clean and efficient technology to utilize coal resources,and can obtain clean fuel or some special-value chemicals,such as humic acid,through the action of microorganisms.This paper mainly carried out the research and development of mineral-sourced humic acid compound microbial agent,and explored the mechanism of of transforming lignite to produce humic acid with microbial agent.Finally,the laboratory samples of compound microbial agent were prepared to evaluate the relevant indicators and verify the specific effects of the microbial agent on crops.The humic acid production test of lignite transformed by microbial in culture medium was used to compare the total humic acid content and soluble humic acid content of lignite after biotransformation with raw coal,the results showed that the total humic acid production of lignite by fungi was better,and the total humic acid in the residual coal treated by AH,H3,Trichoderma reesei and Aspergillus oryzae were38.39%,37.82%,35.52% and 32.66%,respectively.The content of soluble humic acid produced by transforming lignite with bacteria increased,and the two strains of Y and Bacillus subtilis were 7.28% and 7.27% respectively.Therefore,AH,H3,Trichoderma reesei,Aspergillus oryzae,Y,Bacillus subtilis,4 fungi and 2 bacteria werer selected as the combination objects of microbial agent by combining the two indicators.Perform a combination test on strains,and pairs of combinations of fungi and bacteria without antagonistic effects were tested.According to the measurement results of total humic acid,Y+ Aspergillus oryzae,Y+H3,Bacillus subtilis +Aspergillus oryzae combined effect were better,the total humic acid content of residual coal were 59.02%,51.63%,56.12%,respectively.From the perspective of soluble humic acid content of residual coal,Y+ Trichoderma reesei,Y+H3,Bacillus subtilis +H3 had better effects,and the contents of residual coal were 24.93%,22.88%and 27.50%,respectively.Therefore,four strains of Bacillus subtilis,Y,H3,and Aspergillus oryzae were finally selected for compounding according to two index factors.Through single factor experiment and orthogonal experiment,the best compounding ratio was determined to be Bacillus subtilis: Y: Aspergillus oryzae:H3=3:3:2:5,the total humic acid content in the residual coal transformed by the microbial agent prepared according to the compound ratio was 64.41%,and the soluble humic acid content was 33.44%.Compared with the characterization results of coal samples before and after transformation,it can be concluded that the action of compound microbial agents may cause some changes in coal structure,reduce the ash content or mineral content in the coal and increase the content of H,O,N.Part of the unsaturated C combined with the H element in the coal became saturated C,and the content of C-C/C-H and O=C-O functional groups was relatively increased,indicated that the agent may also decompose some complex benzene ring structures in the lignite,and combine different functional groups to transform them into some small molecules of humic acid containing O,H,and N.Through the analysis of the change of enzyme activity in the transformation process,it was found that the activities of lignin peroxidase,manganese peroxidase and laccase in the whole process of the compound agent were greater than that of the single strain,and the enzyme activities all increased first and then decreased with the change of time.At the early stage of culture,the enzyme activity increased rapidly to decompose lignite lignocellulosic and humic acid,etc.,for the normal growth of the microorganisms.Then the enzyme activity decreased,which may be due to the production of toxic substances and the natural apoptosis of cells.According to the combination and ratio of the strains obtained in the test,the compound microbial agent was prepared by mixing with Xinjiang lignite,wheat bran and other materials for fermentation.The number of fungi and bacteria was 0.14billion/g,2.23 billion/g,the water content was 15.01%,the fineness was 86.42%,and the p H value of the product was about 5.55,all the indicators met the national6 standards of agricultural microbial agents.It was found that the combination of inorganic fertilizer and compound microbial agent was more beneficial to increase the yield and improve the quality of pakchoi than single fertilizer through pot experiment.