The triggering effect of surfaces and surfactants on heat output, oxygen consumption and size reduction of a starving marine Vibrio

Abstract

The marine Vibrio DW1 exhibited a positive response in heat output to a dialysis membrane surface in the presence of substrate (100 mM sodium glutamate) and, more particularly, in the absence of exogenous substrate (starvation conditions). The latter result paralleled the previously reported decrease in cell volume and increase in oxygen consumption by starving bacteria at a similar surface. Modified Morita's salts (MMS) did not extract nutrients from the dialysis membrane, but an artificial seawater containing tris buffer (ASW-tris) did extract surface active and nutrient materials from the membrane. The ASW-tris membrane extract and a commercial surfactant, Tween 85, were found to mimic the effects of the dialysis membrane surface by inducing a decrease in cell volume, and an increasing oxygen consumption and heat output of Vibrio DW1 even in the bulk liquid. The significance of the adsorption of naturally occurring surfactants at surfaces in relation to the behaviour of bacteria at the surfaces is discussed.