| Antibiotic mycelia dregs(AMDs)were the main by-products in the process of antibiotic production.They were listed as national hazardous wastes because of the high concentration of residual antibiotics.Aerobic composting is considered as one of the economic and promising treatments to deal with AMDs.In this study,lincomycin mycelia dregs(LMDs)were studied.The parameters of physicochemical,microbial and antibiotic resistance genes(ARGs)were all used to assess the co-composting process.The mechanisms of lincomycin degradation and its degradation products were also studied during composting.At last,the LMDs compost was applied to field.The impacts of LMDs compost to the soil were studied.The parameters such as the crop quality,soil enzymes,soil microorganisms and resistance genes in soil were all investigated.Based on all these data,an overall and reliable evaluation of the security of LMDs compost to the environment was acquired.The main contents were as follows:(1)About the co-composting of LMDs and manure,the aerobic composting treatment was evaluated.The results showed the temperature of the co-composting of LMDs and manure could increase like normal sewage slug composting pile.More than 70% lincomycin was removed.Based on the microbial analysis,in the initial phase,because of the high concentration of lincomycin,the microbial communities were greatly different between LMDs and sewage sluge composting piles.As the composting continued to a mature phase,most of the lincomycin was reduced,and the differences between the two microbial communities gradually decreased.(2)In order to further remove lincomycin,furfural slag was used to mix with LMDs and kept the moisture to 55%?60% all over the composting phases.The results showed that the temperature remained above 50? were more than 50 days far more than the co-composting LMDs with manure.At last,after 66 days composting,the removal of lincomycin was up to 99%.LC-MS/MS was performed to analyze lincomycin's byproducts.The results showed the mechanism of lincomycin degradation were mainly hydroxylation,phosphorylation and demethylation.(3)High-throughput sequencing was performed for analyzing the microbial community of the co-composting of LMDs with furfural slag.The results showed that co-composting was beneficial to increase the abundance and diversity of bacterial communities for LMDs' treatment.However,because of the continuous high temperature during composting,the abundance and diversity of fungal communities were decreased sharply.The main bacterial phyla were Firmicutes and Actinobacteria.Ascomycota was the main phylum of the fungal community.The possible bacteria to degrade lincomycin were Cocci and Bacillus.(4)Quantitative PCR technique was used to determine the lincomycin resistance genes.The results showed that the gene lnu A was detected in the LMDs compost and it was proved to participate in lincomycin biodegradation based on the analysis of Pearson's correlation and the lincomycin degradation byproducts.In the meanwhile,erm A,erm B,erm C,sul1 and int I1 were all increased with the growth of bacteria during composting.(5)In order to identify the possible hosts of ARGs and the possible bacteria to degrade lincomycin,the co-occurrence patterns of residual lincomycin,ARGs,int I1 and the bacterial community were investigated using Pearson's correlation analysis.The results showed that Corynebacterium?1,Anaerococcus,norank?0?TSCOR001-H18,unclassified?f?Enterococcaceae,Peptostreptococcus,Gallicola,Lactobacillus,Peptoniphilus,Paenibacillus,sporosarcina and Cerasibacillus were the potential bacteria genera to degrade lincomycin.In the meanwhile,these genera also carried the ARGs of erm C,erm B,erm A and lnu A.int I1 was related with the bacteria of Saccharomonospora,Truepera,Oceanobacillus and Pusillimonas.(6)The experiment of LMDs compost to soil was carried out to determine its ecological risk to the soil.The results showed that the application of LMDs compost could promote the growth of Chinese cabbage.As to enzyme activity,the enzymes of urease,sucrase and catalase were all increased significantly compared with the normal soil.However,with the depletion of nutrients in compost,the enzyme activity and microbial quantity gradually returned to normal soil state level.High throughput sequencing technology was performed to determine the microbial communities.The results showed that the application of LMDs compost did not change the structure of the microbial communities in the soil.Its application just increased the number of microbes.The determination of ARGs showed that the abundances of ARGs were lower and lower with the application of LMDs compost prolonging.There were no significant difference between the LMDs compost and normal soil at last.The application of LMDs compost did not cause the spread of ARGs in the field.Therefore,composting is an effective treatment to deal with LMDs to realize its Harmlessness and resource utilization... |
PDF Full Text Request