kappa-carrageenan/gelatin gel beads for the co-immobilization of aerobic and anaerobic microbial communities degrading 2,4,6-trichlorophenol under air-limited conditions

Alginate and kappa -carrageenan gels were tested as bead materials for the co-immobilization of anaerobic and aerobic microorganisms for the mineraliz ation of 2,4,6-trichlorophenol under air-limited conditions. Chemical, mech anical and thermal culture constraints were pre-defined and the gel resista nces were established. Alginate was quickly eliminated because of its chemi cal instability in the culture media. In anaerobic conditions, the microorg anisms transformed the substrates into CH4 and CO2. The kappa -carrageenan gel did not enable these gases to diffuse. They remained as bubbles in the core of the beads and made the beads float. Gelatin was added to kappa -car rageenan in order to change the carrier properties. No biogas bubbles appea red in the bead core during the cultures in anaerobic conditions and the be ads reacted well to the culture conditions in the reactor. The coimmobiliza tion of the anaerobic and aerobic microbial communities was successfully pe rformed with the kappa -carrageenan/gelatin gel (2% (w/w) of each polymer). The biological activities, measured by the impedancemetry technique, were preserved in the beads.