Multiphasic uptake of D-glucose by an oligotrophic marine bacterium

Abstract

Uptake of D-glucose in the range 2.5 x 10 super(-9) M to 4.0 x 10 super(-3) M by an oligotrophic marine bacterium, LNB-155, could be represented by 4 phases of a single, multiphasic mechanism. Other kinetic models did not give a good fit. Sharp transitions occurred at about 1.6 x 10 super(-6) M, 10 super(-5) M and 2 x 10 super(-4) M. Values for K sub(m) and V sub(max) increased regularly upon transition to higher phases. Multiphasic uptake mechanisms in LNB-155 indicate adaptation to living in environments with fluctuating levels of D-glucose. These observations are consistent with the hypothesis that pelagic marine bacteria experience considerable fluctuations in nutrient concentration in their microenvironment.