| China is a large agricultural country,which produces about 1 billion ton of waste every year,more than 60% of the crop straw is burned or abandoned,not only seriously pollute the environment,but also a waste of resources.Chlorpyrifos is a kind of broad-spectrum organophosphorus pesticides,which is mainly used in pest control.As one of the world's most widely used pesticides,which is widely used in agricultural production to improve crop yield,but also to bring the threat to food safety,which has constituted a serious harm to human's health.Bioremediation of organic pollution by composting,is the technology of repairing the environment to use functional microorganisms to compost,and for degradating pesticides and other organic pollutants at the same time.The technology has been paid more and more attention in the remediation of organic pollutants,and has achieved ecological recognition.Using microbial composting to make the agricultural waste such as straw into bio-organic fertilizer,and to degradate the residue of chlorpyrifos,which not only realizes the restoration of chlorpyrifos contaminated environment,but also realizes the utilization of agricultural organic waste,which is also of great significance to food safety.In this study,38 strains with cellulose degradation abilities were screened from natural ecological environment,and then screened 20 strains from the 38 strains to construct 25 groups of complex microbial strains.Through the study of enzyme activities of 25 groups of complex strains,1 group of CD53LS14 TD21CD52 which also had a degradation effect on Chlorpyrifos were obtained.The complex strains were inoculated into the agricultural organic waste as a compound microbial inoculum for composting.It was found that the compound microbial agent could not only promote the composting,but also improve the quality of compost.The composite microbial agent could be applied to the remediation technology of organic waste contaminated by Chlorpyrifos,and be further studied on the engineering bacteria for bioremediation of chlorpyrifos contaminated by Compost.The main contents of this paper were as follows.?Using cellulose-restricted growth medium,38 strains of cellulose-decomposing bacteria were isolated from four natural habitats(toilet dung,cow dung,lake sediment,toilet dung humus soil).The cellulase activity of these bacterial strains at different temperatures were determined by the3,5-dinitrosalicylic acid colorimetry(DNS)method.Thethe effects of temperature(35 ?,45 ? and55 ?)on the strain CMC enzyme activity showed that the most of strains were sensitive to change their enzyme activities in different temperature,their temperature dependence was very strong,with the increase of temperature,the enzyme activities showed a decreasing trend;when the temperature was45 ?,the enzyme activities were more active;as the temperature increased to 55 ?,the enzyme activities of most strains began to decline or no activity.?20 strains were screened out from the 38 strains and divided into 4 groups.According to the orthogonal combination of the 4 factors and 5 levels,25 sets of compound microbial strains were constructed by combining 4 strains.DNS method was used to study the CMC enzyme activities of thesecompound microbial strains in 35?,45?,55?,p H6,pH7.5,pH10,and their FPA activities at 35 ?(pH7.5).The results showed that the activities of CMC enzyme and the activities of FPA of CM17 were significantly higher than those in other 24 groups under different temperatures and different pH conditions,their enzyme activities were130.260 U/m L?107.747U/mL?95.429 U/mL?54.298U/mL?95.429U/mL?105.482U/mL?23.716U/mL.Compared with the other 24 compond strains,the CM17 complex had better environmental tolerance,and it could maintain good enzyme activity at different temperatures and different acid and alkali conditions.?Compared with the single strain,CM17 complex strains were more favorable for cellulose decomposition,and there was a good synergistic degradation between the strains.(1)Under the same conditions,the same weight of the filter paper,CM17 complex strains just needed more than 72 h to degradate,the other single stain,CD53,LS14,TD21,CD52 strains respectively needed 7d,11 d,15d and 18 d,the CM17 strains of cellulose decomposition efficiency was at least 2.33 times of the single strain.(2)No matter in constant temperature or unconstant temperature,the p H of the CM17 complex strains changed little in the course of culture,both in 7 to 8;There was no significant difference in the activity of FPA enzyme in different strains at different temperatures.The change of temperature had little effect on the degradation of cellulose.The synergy between the strains was enhanced by mixing,which was useful to decreased the effect of temperature on the enzyme activity.(3)With the filter paper as the sole carbon source,the 72 h filter paper disintegration test of different proportions of the CM17 compound,it was found that when the mixing ratio was 1:1:1:1,the compound microbial agent had the best synergistic degradation effect,which was also the best mixed proportion of the preparation.?CM17 complex strains and CD53,LS14,TD21 and CD52 could degradate Chlorpyrifos.After the degradation of 48h at constant temperature of ph7-8,35?,the degradation rates of them were73.78±16.74%,64.80±10.31%,73.07±9.13%?74.08±11.54%,and 74.73±8.30%.When the initial chlorpyrifos content was 0.1 g/mL,the degradation rates of chlorpyrifos of CM17,CD53,LS14,TD21and CD52 were 91.58%,70.68%,79.25%,65%and 66.6%.When the initial chlorpyrifos content was900g/mL,the degradation rates were 70.53%,32.11%,61.04%,35.11%,52.10%.There was a negative correlation between the initial chlorpyrifos content and the biodegradation rate of Chlorpyrifos,The higher the initial chlorpyrifos content,the lower the biodegradation rate,the higher content of chlorpyrifos had a certain degree of toxic effect on the strains.F-test showed degree of deviation between each single strain CD53,LS14,TD21,CD52 and CM17 strains,each degree of deviation was0.1535,0.9523,0.1511,and 0.7952,respectively.In the biodegradation of chlorpyrifos,there was no significant synergistic effect between the CM17 strains.CD52 and LS14 had good biodegradation effect on Chlorpyrifos.The order of the degradation of chlorpyrifos by each strain was CD52>LS14>TD21>CD53.In the degradation of chlorpyrifos,the synergistic degradation of chlorpyrifos was not significant.???Setting up three stacks(control CK;CM17 reactor which inoculated by CM17 microbialinoculum;NG reactor which inoculated by the market common microbial agent),using organic waste such as vegetable straw material to be crude material,adjusting the material's C/N between 25:1 ~ 35:1,about 65% of the moisture content,pH7-8,to start compost fermentation test with 42 d.The results showed that compared with the control CK reactor,the total nitrogen,total phosphorus,total potassium,bulk density,total porosity and water holding porosity of the CM17 reactor and the NG reactor,were126%,120%?119%?84%?115%?117% and 140%?133%?119%?81%?121%?122%,respectively;the CM17 reactor and the NG reactor could rise temperature rapidly and hold high temperature for a longer time,their maximum temperature was 61? and 63?,CK reactor was only 53?;In the composting process,the pH value of the three piles fluctuated between the neutral and weak alkaline range,the value of EC,TN,NH+4-N,NO-3-N,and free amino acids' s change trend was basically similar;in the end of 42 d fermentation,the content of the humic acid was 13.1%(CK),14.9%(CM17),15.7%(NG).The above results showed that the CM17 compound could effectively promote and optimize the composting process,rapidly increase the temperature of the reactor,prolong the time of high temperature,shorten the period of maturity,and improve the quality of compost,increase the content of N,P,K and so on.?The CM17 strains are the multifunctional compound microbial inoculums,which have the ability to degrade chlorpyrifos and cellulose decomposition,could be applied to repair the organics and soil,which contaminated by Chlorpyrifos,to non-toxic organic matter,also could be used for organic waste compost,and could be of great significance to study the application of remediation technology for organic pollution. |
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