?Process development for the production of a thermostable steryl glucosidase in Escherichia coli?.

EBERHARDT, FLORENCIA; AGUIRRE, ANDRES; PAOLETTI, LUCIANA; HAILS, GUILLERMO; CASTELLI, MARÍA EUGENIA; PEIRÚ, SALVADOR; MENZELLA H. G.

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017

Biodiesels are renewable fuels consisting of fatty acid methyl esters synthesized via transesterification of oils and fats with shortchain alcohols. They offer several technical advantages over petrodiesel, but some unwanted side products that form insoluble contaminants are also generated. These insoluble precipitates consistmainly on sterile glycosides (SGs). Our working group has describedan efficient method for the removal of SGs of biodiesel based on theuse of an enzyme with steryl glycosidase activity. The SGase is athermostable β-glucosidase from Thermococcus litoralis, which wasexpressed in Escherichia coli. The production process has beenoptimized through the use of different promoters, the coexpressionof molecular chaperones and development of a fed-batch process,reaching a title 260U/ml and productivity 36 U/ml/hour. In this workwe describe the effect of using different carbon sources (glucose,glycerol, crude glycerol, sucrose and molasses) in high cell densityfermentations of E. coli. Furthermore the effects on the production ofthe enzyme for different feeding strategies and different C/N ratios atthe stage of post-induction were analyzed. Changes in fermentationconditions increased productivity 1.7 times, which directly impactson the costs of the industrial process for the treatment of biodiesel.Keywords: Biodiesel, oil, sterile glycosidase, fermentations.