Systems Biology Program, Centro Nacional de Biotecnología-CSIC, Campus de Cantoblanco, 28049, Madrid, Spain.
Environ Microbiol. 2014 Jan;16(1):291-303. doi: 10.1111/1462-2920.12309. Epub 2013 Nov 18.
Although the flagellar machinery of environmental bacteria endows cells with a phenomenal survival device, it also consumes much of the metabolic currency necessary for fuelling such a vigorous nano-motor. The physiological cost of flagella-related functions of the soil bacterium Pseudomonas putida KT2440 was examined and quantified through the deletion of a ≈ 70 kb DNA segment of the genome (≈ 1.1%), which includes relevant structural and regulatory genes in this micro-organism. The resulting strain lacked the protruding polar cords that define flagella in the wild-type P. putida strain and was unable of any swimming motility while showing a significant change in surface hydrophobicity. However, these deficiencies were otherwise concomitant with clear physiological advantages: rapid adaptation of the deleted strain to both glycolytic and gluconeogenic carbon sources, increased energy charge and, most remarkably, improved tolerance to oxidative stress, reflecting an increased NADPH/NADP(+) ratio. These qualities improve the endurance of non-flagellated cells to the metabolic fatigue associated with rapid growth in rich medium. Thus, flagellar motility represents the archetypal tradeoff involved in acquiring environmental advantages at the cost of a considerable metabolic burden.
虽然环境细菌的鞭毛机械赋予了细胞一种非凡的生存装置,但它也消耗了大量代谢货币,这些货币是为了给这种强劲的纳米马达提供燃料。通过删除土壤细菌恶臭假单胞菌 KT2440 基因组中约 70kb 的 DNA 片段(约 1.1%),检测并量化了与鞭毛相关的功能的生理代价,该片段包含了该微生物中相关的结构和调节基因。由此产生的菌株缺乏在野生型恶臭假单胞菌菌株中定义鞭毛的突出极性索,并且无法进行任何游动运动,同时表面疏水性发生显著变化。然而,这些缺陷也伴随着明显的生理优势:缺失菌株对糖酵解和糖异生碳源的快速适应,增加了能量电荷,最显著的是,提高了对氧化应激的耐受性,反映出 NADPH/NADP+ 比值的增加。这些特性提高了无鞭毛细胞在富含营养的培养基中快速生长时对代谢疲劳的耐力。因此,鞭毛运动代表了在获得环境优势的同时,以相当大的代谢负担为代价的典型权衡。