González Vara Antonio, Rossi Maddalena, Altomare Luigi, Eikmanns Bernhard, Matteuzzi Diego
Department of Industrial Materials Chemistry, Faculty of Industrial Chemistry, University of Bologna, Bologna, Italy.
Biotechnol Bioeng. 2003 Oct 20;84(2):145-50. doi: 10.1002/bit.10737.
Bifidobacterium animalis ATCC 27536 represents among bifidobacteria a host-model for cloning experiments. The segregational and structural stabilities of a family of cloning vectors with different molecular weights but sharing a common core were studied in continuous fermentation of the hosting B. animalis without selective pressure. The rate of plasmid loss (R) and the specific growth rate difference (delta mu) between plasmid-free and plasmid-carrying cells were calculated for each plasmid and their relationship with plasmid size was studied. It was observed that both R and the numerical value of delta mu increased exponentially with plasmid size. The exponential functions correlating the specific growth rate difference and the rate of plasmid loss with the plasmid molecular weight were determined. Furthermore, the smallest of the plasmids studied, pLAV (4.3-kb) was thoroughly characterized by means of its complete nucleotide sequence. It was found that it contained an extra DNA fragment, the first bifidobacterial insertion sequence characterised, named IS 1999.
动物双歧杆菌ATCC 27536是双歧杆菌中用于克隆实验的宿主模型。在无选择压力的情况下，对宿主动物双歧杆菌进行连续发酵，研究了一系列分子量不同但具有共同核心的克隆载体的分离稳定性和结构稳定性。计算了每种质粒的质粒丢失率（R）以及无质粒细胞和携带质粒细胞之间的比生长速率差异（δμ），并研究了它们与质粒大小的关系。观察到R和δμ的数值均随质粒大小呈指数增加。确定了将比生长速率差异和质粒丢失率与质粒分子量相关联的指数函数。此外，通过其完整的核苷酸序列对所研究的最小质粒pLAV（4.3 kb）进行了全面表征。发现它包含一个额外的DNA片段，这是第一个被表征的双歧杆菌插入序列，命名为IS 1999。
