GROWTH OF BACTERIA ON THE SURFACE OF ANION-EXCHANGE RESIN

I. EXPERIMENT WITH BATCH CULTURE

Abstract

Bacterial cells adsorbed on an anion-exchange resin, Dowex 1, were incubated in a growth medium. Cell concentration in the liquid part of culture increased gradually at first (first step) and then rapidly (second step). With an incomplete medium or a medium which contains chloramphenicol, secondary rapid increase of the cells was not observed. The rate of secondary increase was much greater than the specific growth rate of free cells. These observations show that the first step is attributable to desorption of adsorbed cells from the resin without growth, while the second step is to detachment of adsorbed cells through growth and the rate of secondary increase reflects the growth rate of adsorbed cells.
As the initial density of adsorbed cells increased, length of the first step decreased and the minimum length of which was 1 to 2hr. Relationship between the relative growth rate and pH shows that the optimum pH for growth of adsorbed cells is about one unit higher than that of free cells. It was observed that resin has many physiological influences not only on adsorbed cells growing on its surface but also on the cells detached from it as a result of growth, the most remarkable influence being shown in the case of enzyme induction.