Effect of growth temperature on hydrolytic and esterifying activities fromPseudomonas fragi CRDA 037 grown on whey

The production of hydrolytic and esterifying activities of Pseudomonas frag i CRDA 037 grown on a whey-based medium was investigated at different tempe ratures over time. The optimal temperature was found to be critical and dif ferent for the production of both activities. The highest hydrolytic activi ty was detected with bacteria cultivated at between 24 degrees C (149.2 U/l iter) and 27 degrees C (133.8 U/liter), while the highest production of eth yl valerate (esterifying activity) was observed by using biomass grown at 1 5 degrees C (0.75 U/liter). When the fermentation temperature was increased , the incubation time necessary to reach the maximal concentration of both activities was reduced. Studies of the thermostability of both activities s howed that the hydrolytic activity was more stable than the esterifying act ivity at 15 and 24 degrees C. Statistical analysis allowed the determinatio n of the equations that predicted the production of hydrolytic and esterify ing activities as a function of time and growth temperature. The optimal as say temperatures for the hydrolytic and esterifying activities were 37 degr ees C and 12 to 15 degrees C, respectively.