Jolanta Krzyczkowska

Studies on the lipolytic activity of sonicated enzymes from Yarrowia lipolytica

The aim of this study was to evaluate the efficiency of sonication in releasing protein from a widespread lipase-producing yeast, Yarrowia lipolytica KKP 379, and to examine the impact of ultrasound waves generated in a horn-type sonicator on the lipolytic activity of Y. lipolytica in the hydrolysis of p-nitrophenyl laurate. In this paper, we focused on a few parameters of ultrasound cell disruption, such as the time of sonication, acoustic power, storage time of the frozen yeast biomass used in sonication and the solvent used to suspend the yeast cells which were considered as the most important part in the process of obtaining a biocatalyst from Y. lipolytica for organic synthesis. The most effective additive in protein release proved to be 2% Tween 80; other ideal parameters of the process were ultrasonic power at 150 W for 15 min and 9 weeks of frozen biomass storage time. The sonication parameters, which were the best for protein release, did not seem to be the most effective for obtaining high lipolytic activity due to denaturation as an effect of cavitation.

Catalytic activity of baker's yeast in ester hydrolysis

Abstract The hydrolysis of phenyl esters of alkane carboxylic acids in the presence of lyophilized Saccharomyces cerevisiae has been studied. In the case of phenyl acetate the hydrolysis obeyed Michaelis–Menten kinetics, behavior typical of esterase-catalyzed reactions. For phenyl laurate our experiments provided evidence for the growth-associated production of lipase by bakers yeast.

Synthetic and Natural Lipase Inhibitors

Lipases are enzymes that catalyse the hydrolysis of ester bonds of triglycerides ranging among biocatalysts of considerable physiological significance and industrial potential. Better understanding of the catalytic functions and achieving the possibility to control the biocatalysis process, in particular exploring some activators and inhibitors of lipases, seems to be crucial in the context of novel applications. The lipase activity is a function of interfacial composition: the enzyme can be there activated as well as denaturated or deactivated and the interface is an appropriate site for modulating lipolysis. Lipase inhibitor, interacts directly with the enzyme and inhibits lipase action. Alternatively, some compounds can postpone the lipolytic reaction via adsorption to the interphase or to the substrate molecules. The aim of this review is to summarise the current knowledge concerning human, animal and microbial lipase inhibitors, which were grouped into two categories: synthetic lipase inhibitors (including phosphonates, boronic acids and fats analogues) and natural compounds (including β-lactones and some botanical foodstuffs - plant extracts and plant metabolites, mainly polyphenols and saponins as well as peptides and some dietary fibers). The topics discussed include also inhibition issues from the viewpoint of obesity treatment. Among natural compounds able to inhibit lipase activity are β- lactones including orlistat. Orlistat is the only registered drug for obesity treatment in many countries and lipases are essential enzymes for lipid absorption - thus fat absorption or obesity can be controlled by lipase inhibition, especially pancreatic lipase which is responsible for the hydrolysis of over 80% of total dietary fats. Its effectiveness in obesity treatment was also described.

Effect of Oils Extracted from Plant Seeds on the Growth and Lipolytic Activity of Yarrowia lipolytica Yeast

This study was aimed at evaluating the capability of Yarrowia lipolytica W29 for the synthesis of lipolytic enzymes in a medium containing plant oils from non-conventional sources with some components displaying bioactivity. Oils from almond, hazelnut, and coriander seeds were obtained by using n-hexane (Soxhlet method) and a chloroform/methanol mixture of solvents (Folch method), and their effect on the growth and lipolytic activity of Y. lipolytica was compared. A comparison of these two extraction methods showed that the extraction with n-hexane was less effective regarding the oil extraction yields than the extraction conducted according to Folch’s procedure. The lipolytic activity of the studied yeast was higher in the culture media containing oils extracted with the Soxhlet method than the Folch method but it was lower compared to olive oil medium. Among all oils tested, almond oil extracted with n-hexane was the best inducer of extracellular lipases synthesized by Y. lipolytica. Its lipolytic activity achieved the maximum value of 2.33 U/mL after 48 h of culture. After 24 h of culture, it was close to the value obtained for the medium containing olive oil. Almond oil was a source of oleic and linoleic acids, which may determine differences in the lipolytic activity. The linoleic acid content in almond oil was higher than that found in other oils. When n-hexane was used for extraction, the resultant oils were characterized by lower contents of polyphenols and poorer antioxidative activity.

Regioselective hydrolysis of acetates in the presence of different yeast strains

The model compound, hexane-1,2-diol diacetate, was hydrolyzed in the presence of supernatant obtained after cultivation of 4 yeast strains: Pichia jadinii, Rhodotorula glutinis and Yarrowia lipolytica KKP 379 and Saccharomyces cerevisiae 102 to evaluate the type of catalysis. The regioselectivity of extracellular enzymes as a function of hydrolysis towards primary and secondary acetic acid ester groups was monitored. The enzymes secreted by P. jadinii, R. glutinis and Y. lipolytica KKP 379 exhibited high regioselectivity towards primary position, while those from S. cerevisiae showed practically no discrimination between the ester groups.