Amino acid assimilation and respiration by attached and free-living populations of a marinePseudomonas sp.
The uptake kinetics of leucine and the assimilation and respiration of leucine, glycine, glutamate and arginine by a marinePseudomonas sp. was evaluated to determine whether the uptake and efficiency of substrate utilization of free-living bacteria differed from that of bacteria associated with surfaces. Bacteria were allowed to attach to plastic substrata with known hydrophilicities, as measured by advancing water contact angle (θ A); these were Thermanox, poly(vinylidene fluoride), poly(ethelene) and poly(tetrafluoroethylene). The assimilation and respiration of surface-associated bacteria depended on the amino acid and substratumθ A, but assimilation by surface-associated cells was generally greater than and respiration was generally less than that by free-living bacteria. The uptake kinetics with leucine demonstrated that the half saturation constant (K) of surface-associated bacteria was greater than that for free-living cells. The Vmax values for surface-associated and free-living bacteria were similar, except for cells associated with poly(tetrafluoroethylene), which had a higher Vmax value.
Department of Environmental Sciences, University of Warwick, CV4 7AL, Coventry, UK.
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Bright
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Fletcher