β-Galactosidase production by the psychrotolerant yeast Guehomyces pullulans 17-1 isolated from sea sediment in Antarctica and lactose hydrolysis

Abstract

A psychrotolerant yeast Guehomyces pullulans 17-1 was isolated from sea sediment in Antarctica. It was found that it could yield both extracellular and cell-bound β-galactosidase. After optimization of the medium and cultivation conditions, it was found that the yeast strain produced over 17.2 U mL⁻¹ of β-galactosidase activity within 120 h at the flask level while the yeast strain produced over 25.3 U mL⁻¹ of β-galactosidase activity within 144 h during the 2-L fermentation. This is the highest β-galactosidase activity produced by the wild type yeast strains reported so far. However, the optimal pH and temperature for the crude β-galactosidase were 4.0 and 50 °C, respectively. Lactose could be converted into glucose and galactose and a large amount of reducing sugar could be released from milk under catalysis of the yeast culture.

Enhanced β-Galactosidase Production from Whey Powder by a Mutant of the Psychrotolerant Yeast Guehomyces pullulans 17–1 for Hydrolysis of Lactose

“…In our previous studies [7], it was found that the psychrotolerant yeast G. pullulans 17-1 isolated from sea sediment in Antarctica could produce over 17.2 U/ml of β-galactosidase activity within 120 h at the flask level. In order to further enhance β-galactosidase activity produced by the yeast strain, its cells were treated using NTG as described in "Materials and Methods".…”

Occurrence and diversity of marine yeasts in Antarctica environments

“…With optimizing the medium and cultivation conditions, the yeast strain G. pullulans 17-1 could produce over 17.2 U mL -1 of β-galactosidase activity, which was the highest in the wild type yeasts reported so far (Song et al, 2010).…”

“…To isolate yeasts, 2.0 g of the sediments was suspended in 20.0 mL of YPD medium (20.0 g L -1 polypeptone, 20.0 g L -1 glucose and 10.0 g L -1 yeast extract) prepared with seawater and supplemented with 0.5 g L -1 chloramphenicol and cultivated at 15℃ for 5 d. Then the sample was diluted and plated on the YPD plates with 0.5 g L -1 chloramphenicol and the plates were incubated at 15℃ for 5 d. Different yeast colonies from the plates were transferred to the YPD slants (Song et al, 2010).…”

The Role of Extremophilic Microorganisms and their Bioproducts in Food Processing and Production

“…Several other cold-active ␤-galactosidases have been identified and characterized; these include those from Arthrobacter psychrolactophilus strain F2 (Nakagawa et al, 2007); Arthrobacter sp. 20B (Białkowska et al, 2009); and the psychrotolerant yeast Guehomyces pullulans 17-1 (Song et al, 2010). Some of these enzymes may be used in lactose hydrolysis in the future.…”