Isolation and identification of a strain producing cold-adapted β galactosidase, and purification and characterisation of the enzyme

Wen-Yu Liu, Ying-Wu Shi, Xin-Qin Wang, Yun Wang, Chang-Qing Wei and Kai Lou
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Wen-Yu Liu: Xinjiang Institute of Microbiology, Xinjiang Academy of Agricultural Sciences, Urumqi, Xinjiang, P. R. China
Ying-Wu Shi: Xinjiang Institute of Microbiology, Xinjiang Academy of Agricultural Sciences, Urumqi, Xinjiang, P. R. China
Xin-Qin Wang: Xinjiang Institute of Microbiology, Xinjiang Academy of Agricultural Sciences, Urumqi, Xinjiang, P. R. China
Yun Wang: Xinjiang Institute of Microbiology, Xinjiang Academy of Agricultural Sciences, Urumqi, Xinjiang, P. R. China
Chang-Qing Wei: College of Food, Shihezi University, Shihezi, Xinjiang, P. R. China
Kai Lou: Xinjiang Institute of Microbiology, Xinjiang Academy of Agricultural Sciences, Urumqi, Xinjiang, P. R. China

Czech Journal of Food Sciences, 2008, vol. 26, issue 4, 284-290

Abstract: Enzymes with high specific activities at low temperatures have potential uses in the food industry. Cold-adapted microorganisms are potentially useful sources of cold-active enzyme. To find cold-adapted β-galactosidase, we isolated several cold-adapted microorganisms from glacier zone soil. One cold-adapted β-galactosidase producing strain was obtained. The biochemical characteristics and the results of 16S rDNA sequencing identified the strain as Rahnella aquatilis. The enzyme was purified by column chromatography after which a single protein band migrating near 60 kDa was observed by means of SDS-PAGE. The β-galactosidase was optimally active at 35°C and at pH 6.5 when assayed with o-nitrophenyl-β-D-galactopyrano-side as substrate. The enzyme activity was sensitive to temperatures above 40°C and was undetectable at 45°C. Metal ions Mn2+and K+ activated the enzyme while Cu2+, Zn2+, Fe3+, and Al3+ inhibited the activity. The enzyme was also assayed for lactose hydrolysis. When milk is treated with the enzyme at 30°C for 2 h, the degree of lactose hydrolysis can reach 80%. It has, thus, potential applications in the food industry.

Keywords: psychrotrophic microorganism; cold-adapted β -galactosidase; lactose hydrolysis (search for similar items in EconPapers)
Date: 2008
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Persistent link: https://EconPapers.repec.org/RePEc:caa:jnlcjf:v:26:y:2008:i:4:id:31-2008-cjfs

DOI: 10.17221/31/2008-CJFS

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