Search

Lipases are used in many food, energy, and pharmaceutical processes. Thus, new systems have been sought to synthesize alternative lipases with potential biotechnological applications. Kluyveromyces marxianus is a yeast with recognized lipase activity; at least ten putative lipases/esterases in its genome have been detected, and two of them possess a signal peptide for extracellular secretion. The study of extracellular lipases becomes more relevant since they usually have higher activity rates than intracellular lipases and simpler purification mechanisms. For these reasons, this study aimed to characterize the production and lipase activity of the putative extracellular lipases of the K. marxianus L-2029 strain, encoded in the genes LIP3 and YJR107W. Both genes were heterologously expressed in Saccharomyces cerevisiae BY4742 (yeast strain without extracellular lipase activity) using a pYES2.1/V5-His-TOPO® plasmid. Herein, we show evidence that the strain transformed with the LIP3 gene did not show lipase activity during flask galactose induction. On the other hand, the strain transformed with the YJR107W gene showed a specific activity of 0.397 U/mg, with an optimum temperature of 37 °C and pH 6. For maximum cell production, glucose and yeast extract concentrations were evaluated by a 22 factorial design, followed by the validation of the best concentrations predicted by a statistical model; a 22 factorial design was also carried out to evaluate the concentration of the inducer galactose on the transformed strains, and the intracellular and extracellular lipase specific activities were quantified. Finally, the biomass and lipase production were determined for each strain, which was grown in a stirred tank bioreactor with a working volume of 1.5 L. The specific activities of the transformed strains obtained in the bioreactor were 1.36 U/mg for the LIP3 transformant and 1.25 U/mg for the YJR107W transformant, respectively.

Resveratrol (3,4′,5-trihydroxy-trans-stilbene, RSV) has emerged as an important molecule in the biomedical area. This is due to its antioxidant and health benefits exerted in mammals. Nonetheless, early studies have also demonstrated its toxic properties toward plant-pathogenic fungi of this phytochemical. Both effects appear to be opposed and caused by different molecular mechanisms. However, the inhibition of cellular respiration is a hypothesis that might explain both toxic and beneficial properties of resveratrol, since this phytochemical: (1) decreases the production of energy of plant-pathogenic organisms, which prevents their proliferation; (2) increases adenosine monophosphate/adenosine diphosphate (AMP/ADP) ratio that can lead to AMP protein kinase (AMPK) activation, which is related to its health effects, and (3) increases the reactive oxygen species generation by the inhibition of electron transport. This pro-oxidant effect induces expression of antioxidant enzymes as a mechanism to counteract oxidative stress. In this review, evidence is discussed that supports the hypothesis that cellular respiration is the main target of resveratrol.