Biofilm build-up of Pseudomonas putida in a chemostat at different dilution rates

Abstract

A test system was set up where the build-up of a biofilm on a defined surface could be studied in a carbon source limited chemostat. The attachment of P. putida ATCC 11172 to glass when growing on L-asparagine was studied at different dilution rates (specific growth rates) from 0.1 to 1.5 h−1 The number of attached colony forming units (cfu) increased with dilution rate from 1×106 cfu/cm2 at 0.1 h−1 to 4×107 cfu/cm2 at 1.0 h−1 and then the attachment decreased to about 6×106 cfu/cm2 at higher dilution rates (1.1–1.5 h−1). The number of attached cfu was measured after 24 h exposure. The value of the maximum specific growth rate in batch culture was 0.6 h−1. The total amount of attached cell-mass followed roughly the same pattern as the viable count. The viable count of the cells suspended in the growth medium showed its lowest value at the same dilution rate as resulted in maximum adhesion. It was shown that the effect of growth rate on the biofilm build-up of P. putida is significant, and ought to be borne in mind when continuous culture systems are set up and results evaluated.