The growing interest in lipases is related to its high biotechnological potential. In this work we investigated the regio- and typo-selectivity of extracellular lipase from Yarrowia lipolytica 583 (IMUFRJ 50682) in its free form and immobilized on magnetic nano-sized particles. Results of p-nitrophenyl laurate hydrolysis showed optimal stability of these biocatalysts at pH 6–8 and between 20 and 45 °C. The immobilization of lipase on nano-sized magnetic particles increased thermo and pH stabilities of the enzyme. Both catalysts displayed high hydrolytic activity on triolein and on triacylglycerols in vegetable oils in 5 min. The free lipase showed a strict 1,3-regioselectivity, whereas the immobilized lipase was only slightly 1,3-regioselective, in hydrolysis reactions of triolein and vegetable oils. Both lipases were able to hydrolyze saturated esters, but showed no typo-selectivity for this group. However, the lipases are selective for the hydrolysis of unsaturated esters, especially for 18:2 fatty acids. These results give a better knowledge of this lipase hydrolytic activity, both in the free form and immobilized and widen their potential biotechnological use, especially in the synthesis of structured lipids. (Résumé d'auteur)

The growing interest in lipases is related to its high biotechnological potential. In this work we investigated the regio- and typo-selectivity of extracellular lipase from Yarrowia lipolytica 583 (IMUFRJ 50682) in its free form and immobilized on magnetic nano-sized particles. Results of p-nitrophenyl laurate hydrolysis showed optimal stability of these biocatalysts at pH 6–8 and between 20 and 45°C. The immobilization of lipase on nano-sized magnetic particles increased thermo and pH stabilities of the enzyme. Both catalysts displayed high hydrolytic activity on triolein and on triacylglycerols in vegetable oils in 5min. The free lipase showed a strict 1,3-regioselectivity, whereas the immobilized lipase was only slightly 1,3-regioselective, in hydrolysis reactions of triolein and vegetable oils. Both lipases were able to hydrolyze saturated esters, but showed no typo-selectivity for this group. However, the lipases are selective for the hydrolysis of unsaturated esters, especially for 18:2 fatty acids. These results give a better knowledge of this lipase hydrolytic activity, both in the free form and immobilized and widen their potential biotechnological use, especially in the synthesis of structured lipids.

International audience | The differentiation of human induced pluripotent stem cells (hiPSCs) into functional hepatocytes has the potential to solve the shortage of human primary liver cells and would be of use in drug screening. In this frame, we developed a hiPSCs maturation strategy in microfluidic biochips, using a liver-on-chip approach, a promising technology mimicking in vivo physiology. Hepato-like tissues differentiated in biochips presented advanced liver features, including ALB and CYP3A4 expressing cells. The metabolomics and transcriptomics profiles of hepato-likes cells differentiated either in biochips or Petri dishes were integrated to compare their functionalities. The multi-omics analysis revealed 41 metabolites and 302 genes differentially expressed. Overall, biochip environment lead to higher degree of hepatic differentiation demonstrated by an increase in the metabolic production of lipids, fatty acids and biliary acids, which was confirmed at the transcriptome level by the modulation of expression for genes involved in related signaling pathways. This observation was correlated with higher production of fructose in biochips, together with down-regulation of genes engaged in glycolysis. In parallel, increased activity of the Krebs cycle, pentose phosphate shuffle, and fatty acid beta oxidation was observed in tissues cultured in Petri. Besides, the modulation of nitrogen metabolism was observed in transcriptomic data and confirmed by an intense production of glutamine, putrescine and creatinine and by the higher consumption of spermidine measured in Petri.

The differentiation of human induced pluripotent stem cells (hiPSCs) into functional hepatocytes has the potential to solve the shortage of human primary liver cells and would be of use in drug screening. In this frame, we developed a hiPSCs maturation strategy in microfluidic biochips, using a liver-on-chip approach, a promising technology mimicking in vivo physiology. Hepato-like tissues differentiated in biochips presented advanced liver features, including ALB and CYP3A4 expressing cells. The metabolomics and transcriptomics profiles of hepato-likes cells differentiated either in biochips or Petri dishes were integrated to compare their functionalities. The multi-omics analysis revealed 41 metabolites and 302 genes differentially expressed. Overall, biochip environment lead to higher degree of hepatic differentiation demonstrated by an increase in the metabolic production of lipids, fatty acids and biliary acids, which was confirmed at the transcriptome level by the modulation of expression for genes involved in related signaling pathways. This observation was correlated with higher production of fructose in biochips, together with down-regulation of genes engaged in glycolysis. In parallel, increased activity of the Krebs cycle, pentose phosphate shuttle, and fatty acid beta oxidation was observed in tissues cultured in Petri. Besides, the modulation of nitrogen metabolism was observed in transcriptomic data and confirmed by an intense production of glutamine, putrescine and creatinine and by the higher consumption of spermidine measured in Petri.