猪粪堆肥过程中可培养耐药菌的抗性研究

Study on antibiotic resistance of culturable resistant bacteria during pig manure composting

摘要:

饲料中常添加抗生素,导致猪粪携带一些耐药病原菌,堆肥是降低猪粪返田环境风险的有效手段,但猪粪堆肥产品耐药菌的特性仍不清晰.为揭示猪粪源堆肥产品中耐药细菌的种类、数量和分布,利用平板计数法、抗生素最小抑制浓度、16S rRNA测序等手段,对猪粪原样和额外添加金霉素CTC（chlortetracycline）猪粪的堆肥产品展开对耐药细菌的数量、抗性和种类的研究.结果表明:堆肥过程中可培养细菌数量是逐渐升高后逐步降低的规律,堆体可培养细菌菌落数远远低于粪便样品.猪粪样品检测到CTC、恩诺沙星ENR（Enrofloxacin）、红霉素ERY（Erythromycin）和磺胺甲基嘧啶SMZ (Sulfamerazine)等药物残留,堆肥结束时,堆体中ENR耐药菌略有增加,SMZ、ERY和CTC 3种耐药菌有效削减.筛选出可培养耐药细菌共25株,多重耐药菌的检出率为20%.粪便好氧堆肥对于耐药菌的数量和种类削减非常有效,但是仍有少部分多重耐药菌存在,对环境造成潜在威胁.

Abstract:

Pig manure often carries antibiotics resistance bacteria (ARB) because antibiotics are usually added in feed. Composting is an effective way to reduce the environmental risk of pig manure returning to the field, but the characteristics of ARB in pig manure composting products are still unclear. The purpose of this study was to reveal the species, number, and distribution of ARB in pig manure composting products. In this study, the number, resistance, and species of resistant bacteria contained in the composting of pig manure and pig manure with additional chlortetracycline (CTC) were investigated through measures such as plate counting, minimum inhibitory concentration (MIC) of antibiotic, and 16S rRNA sequencing. Results show that the number of culturable bacteria in composting process first increased and then decreased, and the number of culturable bacteria in compost was far less than that in fresh manure samples. Antibiotics residues such as CTC, enrofloxacin (ENR), erythromycin (ERY), and sulfamerazine (SMZ) were detected in pig manure samples. At the end of composting, ENR resistant bacteria in the compost increased slightly, while SMZ, ERY, and CTC resistant bacteria were effectively reduced. A total of 25 strains of ARB were screened out, and the detection rate for multi-ARB was 20%. Aerobic composting is effective to reduce the number and types of ARB, but there are still a small number of multi-ARB, which poses a potential threat to the environment.