Klingmüller W, Shanmugam K T, Singh M
Mol Gen Genet. 1983;191(2):221-4. doi: 10.1007/BF00334817.
The nif gene group from Klebsiella can be transferred into Enterobacter cloacae by conjugation using Escherichia coli donor cells carrying the composite self-transmissible nif-plasmid pRD1. A small fraction of the hybrids obtained is stable upon prolonged passaging without selection. Their stability is due to integration of pRD1 into the chromosome. Such integration hybrids were chlorate resistant, and nitrate reductase negative, which indicated that integration preferentially occurred within one of the genes for the production or functioning of this enzyme. Chlorate resistance could, therefore, be used to select for additional nitrate reductase-negative sublines with pRD1 in their chromosome. Such sublines have been analyzed further for the presence of nif genes, other pRD1 markers, and for stability. In all except one the complete plasmid seems to have been integrated. Some tend to revert to nitrate utilisation (chlorate sensitivity).
利用携带复合自传递固氮质粒pRD1的大肠杆菌供体细胞，通过接合作用可将克雷伯氏菌的固氮基因群转移到阴沟肠杆菌中。在不进行选择的情况下长时间传代后，所获得的一小部分杂种是稳定的。它们的稳定性归因于pRD1整合到染色体中。这种整合杂种对氯酸盐具有抗性，且硝酸还原酶呈阴性，这表明整合优先发生在该酶产生或发挥功能的基因之一内。因此，氯酸盐抗性可用于选择染色体中带有pRD1的其他硝酸还原酶阴性亚系。对这些亚系进一步分析了固氮基因、其他pRD1标记的存在情况以及稳定性。除一个亚系外，在所有其他亚系中完整的质粒似乎都已整合。有些亚系倾向于恢复利用硝酸盐（对氯酸盐敏感）。
