Due to the different preference to the esterification and transesterfication,
Novozyme 435 and Lipozyme TLIM were then combined
as tandem lipases for the biotransformation of grease with
methanol to achieve better performance. Since the grease used in
our study contains 21.7% FFA, ratios of Novozyme 435 and Lipozyme
TLIM from 1:9 to 5:5 were examined. As shown in Fig. 1,
the FAME yield at the enzyme ratio of 5:5 was slightly higher than
that of using Lipozyme TLIM alone (76% vs 75%), indicating the synergy
effect of the two lipases. The ratio for the esterification-preferring
Novozyme 435 seemed too high in this case. The FAME yield
was increased to 80% when the enzyme ratio was changed to
2:8. This showed much more clearly the synergy effect of the tandem
lipases in FAME production from the grease. This system gave
higher efficiency than either Novozyme 435 or Lipozyme TLIM