2.6. Biotransformation of grease to biodiesel (FAME) with the recycling
of E. coli cells
A mixture of 2.0 g grease, 80 mg dry cells of recombinant E. coli
(Calb/Tll) (4 wt%), and 98 lL methanol (1:1 mol ratio to grease)
were stirred at 30 C and 500 rpm. Additional two portions of
methanol (each 98 lL) were added at 6 and 12 h. After 48 h, cells
of E. coli (Calb/Tll) were harvested by centrifugation, washed with
tert-butanol twice, dried at 30 C for 2 h, and then re-used for new
batch of biotransformation of grease at the same reaction
conditions.