Fistrovici E, Collins-Thompson D L
Department of Environmental Biology, University of Guelph, Ontario, Canada.
Int J Food Microbiol. 1990 Jan;10(1):43-50. doi: 10.1016/0168-1605(90)90006-q.
Forty-eight isolates of Listeria spp. (19 L. monocytogenes, 27 L. innocua, 2 L. welshimeri) from bulk raw milk were screened for plasmid DNA. These isolates were collected over a period of 1 year. Only L. innocua harboured plasmids (8/27 strains) which ranged in size 10-44 megadaltons. The plasmid bearing strains could be arranged into three groups 10 Md, 44 Md and 44 + 10 Md. In two farms where Listeria innocua were persistent in bulk raw milk different plasmids profiles were found (farm 1 and 3). In species carrying similar plasmid profiles (44 Md) isolated from the same bulk tank raw milk samples over a period of 2-4 months (farm 2) no similarities in restriction endonuclease digest patterns of the plasmids were observed. This study suggests there may be a constant influx of Listeria spp. into raw milk supplies on the farm.
对从生鲜原料乳中分离出的48株李斯特菌属菌株（19株单核细胞增生李斯特菌、27株无害李斯特菌、2株威尔斯李斯特菌）进行了质粒DNA筛查。这些菌株是在1年时间内收集的。只有无害李斯特菌携带质粒（8/27株），质粒大小在10 - 44兆道尔顿之间。携带质粒的菌株可分为三组：10兆道尔顿、44兆道尔顿和44 + 10兆道尔顿。在两个生鲜原料乳中持续存在无害李斯特菌的农场，发现了不同的质粒图谱（农场1和3）。在2 - 4个月内从同一储奶罐生鲜原料乳样品中分离出的携带相似质粒图谱（44兆道尔顿）的菌株中，未观察到质粒的限制性内切酶消化模式有相似之处。这项研究表明，农场的生鲜原料乳供应中可能不断有李斯特菌属菌株流入。
