Kinetics of aerobic phenol biodegradation by the acidophilic and hyperthermophilic archaeon Sulfolobus solfataricus 98/2

Biodegradation of 51-745 mg l(-1) of phenol by a well-acclimatized strain of Sulfolobus solfataricus, a thermoacidophilic archaeon, was studied in batch experiments at 80 degrees C and pH 3.2. Phenol inhibited growth and specific degradation rates (mu and qs). Fitting the experimental growth data with the Haldane model gave the following kinetic parameters: mu* = 0.094 h(-1), K-s = 77.7 mg l(-1), K-i = 319.4 mg l(-1) (R-2= 0.950). The true mu(max), calculated from mu*, was 0.047 h(-1). A volumetric degradation rate (V-max) was calculated by fitting the phenol consumption data with the Gompertz model. The value of V-max increased with initial phenol concentration (S-i) up to 14.4 mg l(-1) h(-1). The qs values, calculated from V-max. were fitted with the Haldane equation, yielding qs(max) of 0.110 gg(-1) h(-1). The yield factor (Y-x/s) depends on S-i and reached a maximum of 0.83 gg(-1) at S-i =93 mg l(-1). S. solfataricus 98/2 displayed low mu(max) and qs(max) but a good tolerance to phenol (fairly high K-i, K'(j), high Y-x/s). This ability to grow on and degrade phenol (93 mg l(-1) < optimal S-i < 175 mg l(-1)) at high temperature and low pH is unique and may be useful for removing phenol from hot acidic contaminated effluents. Other possible application could lie in the production of the enzymes involved in the key steps of phenol degradation provided the cloning of the enzymes-related genes in fast-growing mesophiles. (C) 2012 Elsevier B.V. All rights reserved.