Keness J, Krämer J, Brandis H
Zentralbl Bakteriol Orig A. 1978 Nov;242(2):181-6.
Four bacteriocin (enterocin) producing strains of Streptococcus faecium were examined for extrachromosomal DNA. Three strains proved to harbor minicircular plasmid DNA of uniform length as evidenced by CsCl ethidium bromide density centrifugation and electron microscopy. Molecular weight determination obtained through contour length measurements showed 2.4 X 10(6) dalton for S. faecium 25, 3.4 X 10(6) dalton for S. faecium 3 and 3.8 X 10(6) dalton for S. faecium 59. Elimination experiments for bacteriocin production with intercalating dyes proved sterile. The role of these plasmids remains for the time being unknown.
对四株产细菌素（肠球菌素）的粪肠球菌菌株进行了染色体外DNA检测。通过氯化铯溴化乙锭密度离心和电子显微镜证明，三株菌株含有长度一致的微小环状质粒DNA。通过轮廓长度测量获得的分子量测定结果显示，粪肠球菌25的分子量为2.4×10⁶道尔顿，粪肠球菌3为3.4×10⁶道尔顿，粪肠球菌59为3.8×10⁶道尔顿。用嵌入染料进行的细菌素产生消除实验证明是无菌的。这些质粒的作用目前尚不清楚。
