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 putidaKT2440 was examined and quantified through the deletion of a approximate to 70kb DNA segment of the genome (approximate to 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.
Martínez-García, E., Nikel, P. I., Chavarría, M., & de Lorenzo, V. (2014). The metabolic cost of flagellar motion in Pseudomonas putida KT2440. Environmental Microbiology, 16(1), 291-303. https://doi.org/10.1111/1462-2920.12309