Evaluation of Encapsulated Lipase Activity within Emulsion Droplets

05.07.2021
15:00
https://technion.zoom.us/j/94104417439
Itzhak Meir; MSc. Graduate Seminar

Biomassis highly considered as a sustainable and economic source for chemicals. Inparticular, biodiesel can be produced by cellulose hydrolysis to glucose, itsfermentation to ethanol and trans-esterification with triacylglycerols fromwaste or other sources. There is current interest in combined enzymaticprocesses in emulsified systems due to their large surface area, localized masstransfer and ease of separation. Previous work described the formation of astable non-crystalline cellulose coating on emulsified oil droplets. Suchcellulose-coated oil-in-water emulsion droplets were shown to provide aneffective substrate for enzymatic cellulose hydrolysis. Ongoingresearch is aimed at utilization of cellulose-coated emulsions in simultaneoussaccharification and fermentation and combining a cascade of biochemicalprocesses in a “one-pot” biodiesel synthesis. The aim of this study is toevaluate the ability of an enzyme (Lipase, as a model), introduced into theemulsion’s aqueous phase, to be incorporated within the cellulose-coateddroplets and to function effectively in hydrolysis of a fatty acid-esterdissolved in the emulsion core.

 

Inthis presentation, the complex structure of cellulose-coated emulsion droplets ispresented by cryogenic scanning-electron microscopy images. These reveal theinner oil core surrounded by a shell of cellulose hydrogel, encapsulated by athin outer coating of amorphous cellulose. Lipase activity is evaluated by twomethods. a) hydrolysis of p-nitrophenyl dodecanoate (p-NPD) dissolved in n-decaneand emulsified by cellulose, using lipase introduced into the aqueous medium. Activity wasmonitored colorimetrically by the release of p-nitrophenol.b) transesterification of methyl laurate and oleylalcohol emulsified with cellulose. Activity was monitored by GC-MS followingthe production of oleyl laurate. The results of bothexperiments, and the associated control experiments, prove that lipaseintroduce into the aqueous medium is successfully incorporated at the innerinterface within the emulsified droplets between oil and hydrogel, and is henceactive. In addition, conversion of transesterification product (oleyl laurate) is notably higher compared to conversion of hydrolysis bi-product (lauric acid)