Applied Biochemistry and Biotechnology

, Volume 60, Issue 2, pp 107–113 | Cite as

An epimerasic activity on galactose induced by xylose inKluyveromyces sp

  • María Edith Elorza De Orellano
  • Ana María Ponce De Ascheri
  • María Isabel Sanz De Tosetti
  • Rodolfo Segovia
Original Articles


Production of galactose epimerase by anKluyveromyces sp. isolated from Kefir (dairy product) was investigated in batch culture. The microorganism was cultured in media with 1% galactose, 1% xylose, or 0.5% xylose plus 0.5% galactose, in Erlenmeyer flasks shaken at 200 rpm and maintained at 30°C. After 48 h, the biomass was harvested by centrifugation and permeated with 80% ethanol. Permeated cells were suspended in 0.1M sodium phosphate buffer pH 6.5. A part of this suspension was shaken for 17h at 140 rpm. The supernatant, free of cells, was separated. Partial characterization ofKluyveromyces sp. epimerase was carried out in the cellular suspension and the supernatant solution. Enzymatic activity, using galactose as substrate, was measured. The product of this reaction was measured by the use of glucose oxidase. The results indicated: (1) there was a strong effect of xylose on induction of epimerase activity; (2) the epimerase obtained was independent of the energetic cell activity; (3) the epimerase activity in whole cells was similar to the activity obtained from the supernatant; (4) epimerase showed a typical substrate-inhibition curve and dependence on magnesium; and (5) the best pH range was between 5.5 and 6.5 and the optimal temperature was 30°C.

Index entries

Epimerase galactose Kluyveromyces sp xylose 


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Copyright information

© Humana Press Inc 1996

Authors and Affiliations

  • María Edith Elorza De Orellano
    • 1
  • Ana María Ponce De Ascheri
    • 1
  • María Isabel Sanz De Tosetti
    • 1
  • Rodolfo Segovia
    • 1
  1. 1.Laboratorio de Fermentaciones Industriales, Cátedra de Microbiologia Industrial, Facultad de QuimicaBioquimica y Farmacia UNSLSan LuisArgentina

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