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Study of the thermal stability of the beta-galactosidase from Kluyveromyces marxianus URM 7404

Grant number: 18/12493-5
Support type:Scholarships in Brazil - Scientific Initiation
Effective date (Start): September 01, 2018
Effective date (End): July 31, 2019
Field of knowledge:Biological Sciences - Biochemistry
Principal Investigator:Gustavo Orlando Bonilla Rodriguez
Grantee:Isabela Brunozi de Oliveira
Home Institution: Instituto de Biociências, Letras e Ciências Exatas (IBILCE). Universidade Estadual Paulista (UNESP). Campus de São José do Rio Preto. São José do Rio Preto , SP, Brazil


The enzyme beta-D-galactosidase, also called lactase, catalyzes the hydrolysis of milk sugar (lactose), which is not absorbed directly into the bloodstream, releasing D-galactose and D-glucose. Low levels of this enzyme in the small intestine produce lactose intolerance, a condition that affects approximately 65% of people at some level, causing colic, bloating, diarrhea, among other complications. The uses of this enzyme include food processing for taste improvement, solubility, texture and digestibility, and the production of galactooligosaccharides, considered functional foods. Among its sources, yeasts are outstanding, notably those that are considered safe for industrial use, among them Kluyveromyces marxianus. The beta-galactosidase obtained from this source, however does not have its thermal stability properly analyzed, since the majority of researches with structural focus occurred with the enzyme removed from E. coli, being described in the literature mainly studies related to its enzymatic kinetics. The aim of the project is to understand how thermal denaturation of this enzyme occurs through activity and circular dichroism tests, as well as to optimize the enzymatic activity with lactose of the URM 7404 strain isolated from the cheese serum, and compare it with the results already obtained in the literature .