5种大肠埃希氏菌Col质粒接合传递实验研究

STUDY ON CONJUGATION AND TRANSFER OF COL PLASMID HARBORING IN FIVE SPECIES OF E. COLI

以5种61株Col^+大肠埃希氏菌为供体,与受体E.Coli K_(12)进行接合实验,结果有16株供体菌的Col质粒传递给K_(12),占25.4％。其中NPEC、ETEC、EPEC、EIEC、EAEC的传递比率分别是8/22、 4/21、2/15、1/2、1/1。按传递方式分类,52株耐药供体菌有10株的Col质粒和耐药标记(或R质粒)发生共同传递,占19.2％,伴发Col质粒传递的耐药标记有8种,其中TC、SM、COS、KM的并发传递率较高(16—20％)。不同耐药标记菌株的Col质粒传递率范围在0—66.7％。在8株敏感菌和1株耐药菌中有6株Col质粒发生单独传递,占66.7％。实验发现4个配对组的Col质粒和R(r)质粒发生分离而独自传递。本文分析了Col质粒传递方式和耐药性的关系,同时讨论了接合传递的不同方法。为阐明和研究R^+Col^+肠道菌的演变及其对正常菌群生态平衡的影响提供遗传学依据。

Conjugation test was co nducted with 61 strains belonging to five species of E.coli wlith the Col plasmid as donors and E.coli K_(12) as the recipent. As a result, the Col plasmid harboring in 16 donors transferred to K_(12) (25.4%), of which the transfer frequency of NPEC, ETEC, EPEC, EIEC and EAECwas respectively 8/22, 4/21, 2/15, 1/2, and 1/10. Identified by drug sensitivity, co-transfer of Col-R plasmid occurred in 10 of 52 donors (19.2%). Totally 8 kinds of drug markers transferred together with Col plasmid, of which the frequency of TC, SM, COS and KM markers and Col plasmid was higher (16-20%). The transfer frequency of Col plasmid with different drug markers ranged 0% to 66.7% Among 8 strains sensitive to drugs and one strain resistant to drugs, 6 strains could transfer Col plasmid (66.7%) and 4 strains could trainsfer their Col plasmid and R plasmids independently. It was analyzed and discussed the relationship between the transfer of Col plasmid and drug sensitivity and different ways of Col plasmid transfer. A geneticbasis was presented for illustrating and studying the evolution of drug resistance and colicin of entero-bacteria and its influence on the ecologic banlance of coliform bacteria.