Thomas CE, Bailey MJ, Whipps JM, Lynch JM
School of Biological Sciences, University of Surrey, Guildford, Surrey GU2 5XH, United Kingdom.
Appl Environ Microbiol. 1998 Jul 1;64(7):2634-8. doi: 10.1128/AEM.64.7.2634-2638.1998.
An isolate of Pseudomonas fluorescens (SBW25) was modified with different marker genes (lacZY, aph-1, and xylE). These marker genes were inserted singly or in combination into two separate (1 Mbp apart) and presumably nonessential sites (-6- and Ee) on the chromosome of SBW25. This allowed the production of a range of genetically modified SBW25 variants that differed with respect to insertion site of the marker genes and metabolic burden. The environmental fitness of the different SBW25 variants was tested in soil, in the rhizosphere of wheat and pea, and on the phylloplane of wheat. Reduced environmental fitness of the different variants was mainly attributed to the extra metabolic burden of novel gene expression, whereas choice of insertion site was of little significance. Changes in environmental fitness were dependent on the environmental conditions; an environment, such as soil, with a low microbial carrying capacity had a negative effect on the environmental fitness of variants with a large metabolic load. In environments with a larger carrying capacity, such as the rhizosphere of pea, environmental fitness of variants with a large metabolic load was not significantly different from that of variants with a smaller metabolic burden.
荧光假单胞菌（SBW25）的一个分离株用不同的标记基因（lacZY、aph-1和xylE）进行了改造。这些标记基因被单独或组合插入到SBW25染色体上两个相距1兆碱基且可能是非必需的位点（-6和Ee）。这使得能够产生一系列转基因SBW25变体，这些变体在标记基因的插入位点和代谢负担方面存在差异。在土壤、小麦和豌豆的根际以及小麦的叶面上测试了不同SBW25变体的环境适应性。不同变体环境适应性的降低主要归因于新基因表达带来的额外代谢负担，而插入位点的选择意义不大。环境适应性的变化取决于环境条件；像土壤这样微生物承载能力低的环境对代谢负荷大的变体的环境适应性有负面影响。在承载能力较大的环境中，如豌豆根际，代谢负荷大的变体的环境适应性与代谢负担较小的变体没有显著差异。
