Dynamics of the immobilization of anaerobic mesophilic bacteria on a plastic support

In this article, a study of the dynamics of the immobilization of mesophilic anaerobic bacteria was conducted. Low-density polyethylene (LDPE) ground to fine particles was used as immobilization support in an inverse fluidized bed. After 135 d of immobilization, the biomass concentration attained was 375 mu g protein/g dry plastic support. The specific rate for acetate consumption was 0.008 mu mol acetate/mu g protein/h. The kinetic parameters of the bioparticles (K-c = 1.067 mM and V-max = 0.00754 mu mol acetate/mu g protein/h) were estimated by the initial rate method at different acetate concentrations and were compared to the values obtained by a direct parameter estimation method from the dynamic assays for acetate consumption with an initial substrate concentration of 10 mM. The particles were prepared for scanning electron microscopy (SEM) to evaluate the biofilm qualitatively. The SEM studies showed that the surface and cavities of the support were colonized, and the bacterial structures found were bacilli similar to Methanothrix as the predominant microorganism and a few groups of Methanosarcina-like cocci. The K-s value found is between those reported for the predominant bacterial group immobilized.