A. Deleon et al., A POSTFERMENTATIVE STAGE IMPROVES PENICILLIN ACYLASE PRODUCTION BY A RECOMBINANT ESCHERICHIA-COLI, Biotechnology letters, 18(8), 1996, pp. 927-932
Active penicillin acylase is formed only after an in vivo post-transla
tional processing of the polypeptide precursor. Such a maturation proc
ess is rare in procaryotes. In this work, incubation under aerated con
ditions, of whole recombinant E. coli cells after glucose depletion an
d growth cessation, i.e., during the postfermentative stage, consisten
tly resulted in 2- to 4-fold increases in penicillin acylase activity.
Such results suggest that penicillin acylase maturation occurs to a h
igh extent even during the postfermentative stage. Accordingly, the ef
fect of different incubation conditions, during the postfermentative s
tage, on penicillin acylase was determined. incubation under anaerobic
conditions resulted only in a 1.27-fold increase of enzyme activity,
with respect to the end of the batch culture, whereas a 3- and 4-fold
increase occurred during incubation under dissolved oxygen concentrati
ons of 100 and 43% (with respect to air sat.), respectively. Only a sm
all negative effect on the maturation process, was observed during inc
ubation with acetate concentrations above 0.6 g/L. No effect of pH, in
the range of 6.0 to 8.0, was observed.