微生物发酵床猪舍不同发酵等级垫料中大肠杆菌的分离鉴定

摘要

To investigate the distribution and characteristic of E .coli in the microbial-fermenta-tion bed of piggery,litters with different levels of fermentation were used for the isolation,iden-tification and drug sensitivity test of E .coli,to analyze the pathogenicity and drug susceptibility of E .coli in the microbial-fermentation bed of piggery.The results showed that,E .coli could be isolated only from litters with low degree of fermentation (0<△E≤7.63),and totally 41 strains were isolated from litters with 10-5 dilution,but none from litters with higher degree of fermenta-tion (△E>7.63).The number of E .coli reduced along with the fermentation of litters.Among the 41 strains of E .coli,15 were intestinal pathogenic strains,9 of which had astA gene (22%), and 2 strains had sepA gene (4.8%).11 strains were resistant to doxycycline,accounted for 27%of the total.The two strains containing sepA gene had strong resistance to doxycycline.In con-clusion,the microbial-fermentation bed fermentation bed had a inhibitory effect on E .coli which promoted the application of fermentation bed and reusing of litters.%为了研究微生物发酵床不同发酵等级垫料中大肠杆菌的分布及其特性，试验采集了微生物发酵床猪舍不同发酵程度的垫料，进行大肠杆菌的分离鉴定和药敏试验，分析了发酵床中大肠杆菌的致病性和抗生素抗性。试验结果表明，在10-5稀释倍数下，仅在垫料发酵级别为一级的垫料中，即垫料使用时间较短、发酵程度较低（0＜△E≤7．63）的条件下，分离到41株大肠杆菌；而在发酵程度较高的垫料中，即垫料发酵程度二级以上（△E＞7．63）的环境中未分离到大肠杆菌。随着发酵的进行，发酵床中大肠杆菌数量逐渐减少。41株大肠杆菌中含有致泻性大肠杆菌15株，其中具有热稳定肠毒素（astA）基因的大肠杆菌9株，占总数的22％，含耐药性因子（sepA）基因的大肠杆菌2株，占总数的4．8％；耐强力霉素的大肠杆菌11株，占总数的27％。含有 sepA 基因的大肠杆菌具有强耐药性。从以上结果来看，微生物发酵床对猪舍大肠杆菌具有抑制作用，可为发酵床的推广应用及垫料再利用提供一定依据。