THE EFFECTS OF FREEZE-DRYING AND STORAGE ON PHENOL DEGRADATION

Freeze-drying and storage were found to affect the performance of a microbial supplement cultured for phenol biodegradation. After freeze-drying, a lag in phenol degradation was observed which increased with storage. The lag was attributed to reductions in culture viability and lags in enzyme activity, both of which increased with storage. In addition, a switch in the primary pathway for aromatic ring cleavage from catechol 2,3-oxygenase to catechol 1,2-oxygenase occurred after freeze-drying. While freeze-drying and storage adversely affected viability and resulted in both a switch and lag in enzyme activity, increases in the maximum specific growth constant, mu(m), also were observed with this treatment. Both the observed lag in phenol degradation and increases in mu(m) were simulated numerically.