大肠杆菌MG1655菌株ERIC-PCR图谱主带序列组成分析

ERIC-PCR已经在细菌分类，鉴定及混合菌群分析中得到广泛应用，但对其产物形成规律的认识仍存在分歧，以大肠杆菌MG1655为对象，对其ERIC-PCR指纹图谱中1.1kb主带中的DNA片段进行了克隆，测序，基因组定位以及引物匹配分析。结果表明，这条1.1kb主带由分布在基因组中不同位置的3种序列不同的片段组成，各片段的丰度差异较大，最高为97.89%;3种片段中的2种所在的基因组区域仅一端含有ERIC序列，推测对含有ERIC序列的基因组DNA进行扩增时，ERIC-PCR是一种非随机扩增。

NON-RANDOM NATURE OF GENOMIC DNA AMPLIFICATION OF E.COLI K-12 MG1655 VIA ERIC-PCR

ERIC-PCR has been widely used as genomic fingerprinting technology for classification and identification of bacterial isolates. Recently, it has been used by some labs to characterize bacterial mixtures. However, there are still disputes regarding the mechanism of product formation in ERIC-PCR. We cloned and sequenced the 1. 1kb major band of the ERIC-PCR fingerprint of E. coli K-12 strain MG1655, the strain used for whole genome sequencing, and found that the band consisted of 3 different DNA fragments with one fragment the most abundant (93 out of 95 clones, i. e. 97. 89%). Sequence analysis showed that two of the three fragments amplified from a chromosomal region where one ERIC element exist either upstream or downstream, while one fragment amplified from a region where no ERIC element was found. It was thus postulated that ERIC-PCR is not an absolutely random amplified PCR technique, especially when it is applied to those genomes containing ERIC elements.