CONTINUOUS LIMONIN DEGRADATION BY IMMOBILIZED RHODOCOCCUS FASCIANS CELLS IN KAPPA-CARRAGEENAN

Limonin can be effectively degraded by Rhodococcus fascians cells. The se bacteria can be entrapped in K-carrageenan, and used in a continuou s stirred tank reactor to degrade limonin in a continuous process. The effects of temperature, limonin concentration, dilution rate, and aer ation on the reactor behaviour have been tested, and the results corre lated with changes in limonin conversion, substrate degradation rate, and free and immobilized biomass. Results showed that the immobilized cells were able to debitter limonin-containing media and the immobiliz ed biomass was quite stable throughout the operational conditions test ed. A population of free biomass was present in the reactor, the quant ity of which was dependent on dilution rate. The immobilized bacteria increased its limonin-degrading capability when the substrate concentr ation was increased. The aeration was not strictly necessary for limon in degradation. Additionally, the immobilized cells were active and st able for more than 2 months of continuous operation, and were able to recover their limonin-degrading capability when used intermittently. F inally, none of the main components of a juice was noticeably altered during limonin degradation, so the reactor response was good enough to consider its application.