Effect Of Tylosin On Microbial Community Diversity And Resistance Genes During Genetically Modified Cotton Stalk Composting

China is the largest cotton producer of the world,of which 80% of genetically modified cotton,and thus the production of genetically modified cotton stalks is very large,according to statistics,only Xinjiang Autonomous Region cotton straw annual output of up to 6 to 7.5million tons(wet weight).Cotton stalks contain a lot of lignocellulose,crude fiber,nitrogen and phosphorus,etc.,they usually been incinerated,not only a waste of valuable resources and cause environmental pollution.Aerobic compost is considered to be one of the most promising treatments for agricultural solid waste and livestock manure,and the antibiotics in livestock manure are also of widespread concern.In this study,genetically modified and nongenetically modified cotton stalks were used as raw materials and aerobic composting with pig manure,and antibiotics(tylosin),which were widely used in aquaculture industry,were added.Biolog and real-time quantitative PCR were used to study the effects of physical and chemical properties,microbial community diversity,antibiotic resistance gene and ?,?class integron changes.The main results are as follows:1.Effect of genetically modified cotton stalks on antibiotic resistance genes(ARGs)and mobile genetic elements during compostingGenetically modified cotton and non-genetically modified cotton stalks used as composting raw materials,after 40 days of composting,meet the maturity standards.Five kinds of macrolide resistance genes(ermB,ermF,ermQ,ermT,ermX),two tetracycline resistance genes(tetC,tet X),two sulfonamide resistance genes(sul1,sul2),class I and class II integrins(intI1,intI2)were detected in the samples of composting period Genes.At the end of composting,the absolute abundance of ARGs,intI1 and intI2 in genetically modified and non-genetically modified treatments decreased by 5.12 log and 4.45 log,respectively,and the change of ARGs was most significant by temperature and ammonium nitrogen.In addition,there was no difference in the effects of genetically modified cotton stalk and non-genetically modified cotton stalk on most ARGs,intI1 and intI2.Thus,as with non-genetically modified cotton stalks,genetically modified cotton stalks can also be used for aerobic composting with livestock manure and to reduce the abundance of ARGs by composting.2.Effects of tylosin on physical and chemical properties and microbial community diversity in composting processAfter 40 days of composting,the temperatures of the four treatments were above 50?for about 6 days to achieve a harmless treatment requirement.At the end of composting,the pH of the four treatments was between 7.5 and 8.5,and the C/N ratio was less than 20,reaching the maturity standard.The results of Biolog showed that the addition of tylosin could inhibit the initial microbial activity of composting,but with the composting progress,the tylosin gradually decreased in the compost,and the inhibition was gradually disappeared.The diversity index indicated that tylosin affected the functional diversity of microbial community and the dominance of species,and the effect of low concentration of tylosin was more significant at high temperature,and the medium concentration of tylosin could improve the homogeneity of microbial community.And the addition of tylosin can improve the use of microorganisms for six genera of glycogen.3.Effects of tylosin on resistance genes and genetic elements in composting processAfter aerobic composting,the total abundance of ARGs,intI1 and intI2 decreased by8.61 log,9.23 log,9.27 log and 8.17 log,respectively,in CK,L,M and H treatments,respectively,indicating that aerobic composting can effectively reduce resistance gene.16 s rDNA quantitative results showed that the addition of tylosin could increase the abundance of bacteria at the end of composting.Through the RDA analysis,it was found that the environmental variables could explain 54.4% of the total gene abundance changes,and the changes of ARGs,intI1 and intI2 were most affected by pH value,accounting for 19.1% of the total explanations.Aerobic composting is an effective method for the removal of antibiotics,but can not completely remove the resistance gene,so further research is needed to reduce the environmental risk of the resistance gene.Genetically modified cotton stalk and non-genetically modified cotton stalk can be used as fertilizer to compost,and tylosin can inhibit the initial microbial activity of composting and improve the utilization of six kinds of glycogen at the end of compost.In this paper,the ecological risk of composting of poultry manure provides a theoretical basis.