SOLVENT EXTRACTION OF Β-Galactosidase FROM KLUYVEROMYCES LACTIS YIELDS a STABLE AND HIGHLY ACTIVE ENZYME PREPARATION

Abstract

The yeastKluyveromyces lactis was cultured in cheese whey and b-galactosidase was extracted from cells by an organic solvent procedure. Under optimum conditions (pH 8.5, 25C), approximately 90% of the intracellular b-galactosidase activity was released into 0.1 M potassium phosphate solution with 2% chloroform after 9 h. The cell-free extract containing b-galactosidase activity was concentrated and the enzyme partially characterized. This enzyme has exhibited an optimum activity at a pH range of 6.2-6.6 and temperature of 40-45C on O-nitrophenyl-b-D-galctopyranoside. The maximum enzyme activity in milk was found at 45C and the concentrated enzymatic extract was found to have 19 U/mg protein. A feasible preparation for commercial application containing 20% glycerol maintained 89% of activity after 2 months at 4C, demonstrating stability. This preparation analyzed on 5% nondenaturing polyacrylamide gel electrophoresis exhibited two bands suggesting two aggregation forms with b-galactosidase activity. PRACTICAL APPLICATIONSKluyveromyces lactis yeast cells are a safe source of b-galactosidase for food and pharmaceutical industries. Their application to prior hydrolysis of lactose in milk products has become commonplace in alleviating the symptoms of lactose intolerance. It is also of great interest to prevent lactose crystallization in concentrated or frozen dairy products such as condensed 1 Corresponding

Production of Galacto-oligosaccharides by the β-Galactosidase from Kluyveromyces lactis: Comparative Analysis of Permeabilized Cells versus Soluble Enzyme

“…Solvent treatment is an inexpensive method that can be applied on a large scale . Depending on the solvent nature and concentration, as well as the incubation time, the permeability of membranes may be increased enough to lead to disruption of cells, with the concomitant release of enzyme molecules into the supernatant. ,, In our study, the ethanol treatment was not so intense as to produce cell disruption. Although cells treated with short-chain alcohols become nonviable in many cases, intracellular enzymes may resist such treatment and, as a consequence, are not inactivated.…”

“…The major commercial source of β-galactosidase by far is the mesophile yeast Kluyveromyces lactis. − Due to its intracellular nature, the production of cell-free K. lactis β-galactosidase is limited by the high cost associated with enzyme extraction and downstream processing as well as the low stability of the enzyme. , The hydrolytic activity of K. lactis β-galactosidase is very high . The production of GOS using batch and continuous bioreactors of K. lactis β-galactosidase has been reported. , Several studies on the immobilization of this enzyme with different carriers have been also described. ,, …”

Immobilization of β-d-galactosidase from Kluyveromyces lactis on functionalized silicon dioxide nanoparticles: Characterization and lactose hydrolysis

“…The use of beta-d-galactosidase as a therapeutic enzyme to hydrolyze lactose from milk products has become commonplace in alleviating the symptoms of lactose intolerance. Its medical properties are also utilized to treat infants with genetic deficiency of intestinal lactase, and it can also be used to prevent lactose crystallization in concentrated or frozen dairy products such as condensed milk and ice cream, thereby increasing consumer acceptance [3]. Beta-d-galactosidase has potential application in an array of fields such as the food industry, bioremediation, biosensory, diagnosis and treatment of various disorders [4].…”

Extraction of β‐galactosidase from Saccharomyces fragilisIZ 275 grown in cheese whey

“…Purification of the enzyme is ideal, but the costs involved do not make it a viable competitive option. 6,9 An alternative for the purification of ⊎-galactosidase is through tangential flow ultrafiltration with a 10 kDa membrane pore.…”