Transgenic Pseudomonas fluorescens 5-2/4 with reinforced 2,4-diacetyl phloroglucinol (phl) production had shown increased biocontrol ability towards Pythium ultimum (Pu), but inferior root colonization ability compared to its wild type 5.014. Therefore, enhanced root colonization ability of the transgenic strain by repeated inoculation and reisolation on tomato plants was suggested. As a preparation for repeated inoculation and reisolation cycles, the construction of a negative control of the transgenic strain 5-2/4 by marking with lacZY and screening for a mutant possessing qualities comparable to 5-2/4 was performed. Morphologically, colonies of all of the 11 selected mutants were similar on MLXgal medium. The root colonization ability of two of the lacZY-marked strains (mutants 1 and 10) was comparable to the parental strain. These were also able to compete with the resident microflora of tomato seedlings to the same extent as the parental strain. Five mutants were excluded due to lower growth rates on Yeast Malt, King's B Medium (KB) and 0.1 Tryptic Soy Agar (mutant 4, 5 and 8), excessive growth and higher siderophore production on KB (mutant 10) and increased protease production (mutant 2). With respect to in vitro-antagonism of Pu, no differences could be found between the target strain and mutants 1, 3, 6, 7 and 9. Examination of sole carbon source utilization of these five lacZY-marked strains revealed a significantly higher utilization of alpha-D-lactose and lactulose compared to 5-2/4. However, significant differences could be found for 51% of the utilized carbon sources. Cluster analysis showed a high degree of similarity between 5-2/4 and mutant 1 both when analyzed with and without alpha-D-lactose. As mutant 1 also represented the colonization pattern most similar to the parental strain 5-2/4, it presents a presumptive subject for a negative control in the following inoculation and reisolation studies on tomato.

中文翻译：

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产生2,4-二乙酰基间苯三酚的荧光标记伪荧光菌株5-2 / 4的lacZY标记对其生理性能和根部定植能力的影响。

具有增强的2,4-二乙酰基间苯三酚（phl）产量的转基因荧光假单胞菌5-2 / 4已显示出对倒数腐霉（Pu）的生物防治能力增强，但与野生型5.014相比，其根定殖能力较弱。因此，提出了通过在番茄植物上反复接种和再分离提高转基因菌株的根定植能力。作为重复接种和再分离循环的准备，通过用lacZY标记并筛选具有与5-2 / 4相当的质量的突变体来构建转基因菌株5-2 / 4的阴性对照。从形态上讲，所有11个选定突变体的菌落在MLXgal培养基上均相似。lacZY标记的两个菌株（突变体1和10）的根定殖能力与亲本菌株相当。它们还能够与亲本菌株在相同程度上与番茄幼苗的固有微生物竞争。由于酵母麦芽，King's B培养基（KB）和0.1胰蛋白酶大豆琼脂（突变体4、5和8）的生长速率较低，KB的过度生长和较高的铁载体产量（突变体10）以及蛋白酶产量增加（突变体2）。关于Pu的体外拮抗作用，在目标菌株与突变体1、3、6、7和9之间没有发现差异。对这5个lacZY标记菌株的唯一碳源利用进行检测表明，Pu的显着更高的利用。 α-D-乳糖和乳果糖则为5-2 / 4。但是，对于51％的利用碳源，可以发现显着差异。聚类分析显示，在有和没有α-D-乳糖的情况下，5-2 / 4与突变体1之间都具有高度相似性。由于突变体1还代表了最类似于亲本菌株5-2 / 4的定殖模式，因此在随后的番茄接种和再分离研究中，突变体1为阴性对照提供了推定对象。