The effect of oxygen on chemotaxis to naphthalene by Pseudomonas putida G7

Abstract

Chemotactic bacteria can be attracted to electron donors they consume. In systems where donor is heterogeneously distributed, chemotaxis can lead to enhanced removal of donor relative to that achieved in the absence of chemotaxis. However, simultaneous consumption of an electron acceptor may result in the formation of an acceptor gradient to which the bacteria also respond, thus diminishing the positive effect of chemotaxis. Depletion of an electron acceptor can also reduce the rate of electron donor consumption in addition to its effect on chemotaxis. In this study, we examined the effect of oxygen on chemotaxis to naphthalene and on naphthalene consumption by Pseudomonas putida G7. The organism was able to move up an oxygen gradient when there was a naphthalene gradient in the opposite direction. In the absence of an oxygen gradient, low levels of oxygen attenuated chemotaxis to naphthalene but did not affect random motility. The rate of naphthalene consumption decreased at dissolved oxygen concentrations similar to those at which chemotaxis was attenuated. These results suggest that low dissolved oxygen concentrations can reduce naphthalene removal by P. putida G7 in systems where naphthalene is heterogeneously distributed by simultaneously attenuating chemotactic motion toward naphthalene and decreasing the rate of naphthalene degradation.

Analysis of the Pseudomonas putida CA-3 proteome during growth on styrene under nitrogen-limiting and non-limiting conditions

“…These methyl-accepting chemotaxis transducers are outer membrane receptors that mediate chemotaxis to diverse signals, responding to changes in the concentration of attractants and repellents in the environment by changing swimming behaviour (Adler, 1966). This has been observed in P. putida in response to various substances, including naphthalene (Grimm & Harwood, 1997;Harwood et al, 1990;Law & Aitken, 2006). The second group of motilityrelated proteins that was upregulated were flagellar biosynthetic proteins such as FliA, C, F, E, G, K and N. The importance of chemotaxis and flagellins was identified in a study by Raberg and co-workers, who studied flagellation changes in response to nutrient supply and the state of polyhydroxybutyrate (PHB) production in Ralstonia eutropha H16 (Raberg et al, 2008).…”

Influence of Low Oxygen Tensions and Sorption to Sediment Black Carbon on Biodegradation of Pyrene

“…Despite its significance, the capacity for prediction of aerobic biodegradation rates of PAHs at low oxygen tensions is still very limited. Whereas the oxygen dependence of fast biodegradation of PAHs in soils and sediments is a well-known phenomenon (5,17), studies reporting precise measurements of the dissolved oxygen half-saturation constant (K om ) for biodegradation of PAHs-a key modeling parameter-are very scarce (7,21). The only available estimation for a K om value of a high-molecular-weight (HMW) PAH (5.9 M) was provided for pyrene on the basis of growth rates on pyrene of a Mycobacterium strain in a fermenter (7).…”