Some characteristics and isolation of novel thermostable ß-galactosidase from Thermus oshimai DSM 12092

The ß-galactosidases belong to the class of hydrolytic enzymes and have been used as lactose hyrolysis. The enzyme is used in reducing lactose milk production, an outstanding industrial product used by a large lactoseintolerant population. This is the first detailed report of some characteristics of ß-galactosidase and the gene encoding ß-galactosidase in Thermus oshimai DSM 12092. The growth rate (µ, 1/h), and the doubling time (tD, h) for T. oshimai grown both in shaking flasks and in a bioreactor were determined. The optimal temperature and pH for ß-galactosidase were determined as 75°C and 7. 4, respectively. This enzyme was thermostable and was retained by more than 70% at 90°C for 3 h. The ß-galactosidase from T. oshimai DSM 12092 was more stable in basic pH and Zn2+ was the most effective divalent cation. Also, 2 steps of purification consisting of ammonium sulfate precipitation and gel filtration were employed and purified 32-fold. © 2013 The Korean Society of Food Science and Technology and Springer Science+Business Media Dordrecht.