Beta-galactosidase from a cold-adapted bacterium: purification, characterization and application for lactose hydrolysis.

The enzyme beta-galactosidase was purified from a cold-adapted organism isolated from Antarctica. The organism was identified as a psychrotrophic Pseudoalteromonas sp. The enzyme was purified with high yields by a rapid purification scheme involving extraction in an aqueous two-phase system followed by hydrophobic interaction chromatography and ultrafiltration. The beta-galactosidase was optimally active at pH 9 and at 26 degrees C when assayed with o-nitrophenyl-beta-D-galactopyranoside as substrate for 2 min. The enzyme activity was highly sensitive to temperature above 30 degrees C and was undetectable at 40 degrees C. The cations Na+, K+, Mg2+ and Mn2+ activated the enzyme while Ca2+, Hg2+, Cu2+ and Zn2+ inhibited activity. The shelf life of the pure enzyme at 4 degrees C was significantly enhanced in the presence of 0.1% (w/v) polyethyleneimine. The pure beta-galactosidase was also evaluated for lactose hydrolysis. More than 50% lactose hydrolysis was achieved in 8 h in buffer at an enzyme concentration of 1 U/ml, and was increased to 70% in the presence of 0.1% (w/v) polyethyleneimine. The extent of lactose hydrolysis was 40-50% in milk. The enzyme could be immobilized to Sepharose via different chemistries with 60-70% retention of activity. The immobilized enzyme was more stable and its ability to hydrolyze lactose was similar to that of the soluble enzyme.

Geueke, B (författare)
Delgado, OsvaldoLund University,Lunds universitet,Bioteknik,Centrum för tillämpade biovetenskaper,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Biotechnology,Center for Applied Life Sciences,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH(Swepub:lu)biot-ode (författare)
Coleman, J (författare)
Hatti-Kaul, RajniLund University,Lunds universitet,Bioteknik,Centrum för tillämpade biovetenskaper,Kemiska institutionen,Institutioner vid LTH,Lunds Tekniska Högskola,Biotechnology,Center for Applied Life Sciences,Department of Chemistry,Departments at LTH,Faculty of Engineering, LTH(Swepub:lu)biot-rhk (författare)
BioteknikCentrum för tillämpade biovetenskaper (creator_code:org_t)

Ingår i:Applied Microbiology and Biotechnology: Springer Science and Business Media LLC58:3, s. 313-3211432-06140175-7598

Av författaren/redakt...: Fernandes, S; Geueke, B; Delgado, Osvaldo; Coleman, J; Hatti-Kaul, Rajn ...

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