食品科学 ›› 2007, Vol. 28 ›› Issue (11): 350-353.

• 生物工程 • 上一篇    下一篇

产低温β-半乳糖苷酶菌株的筛选及其酶学性质研究

 史应武, 娄恺, 常玮, 欧提库尔   

  1. 新疆农科院微生物所新疆特殊环境微生物实验室; 新疆农科院微生物所新疆特殊环境微生物实验室 新疆乌鲁木齐830091; 新疆乌鲁木齐830091;
  • 出版日期:2007-11-15 发布日期:2011-11-22

Screening and Enzyme Properties of Psychrotrophic Bacterium Producing Cold-active β-galactosidase

 SHI  Ying-Wu, LOU  Kai, CHANG  Wei, 欧Ti-Ku-尔   

  1. Institute of Microbiology, Xinjiang Academy of Agriultural Sciences, Extremophiles Laboratory of Xinjiang, Urumqi 830091, China
  • Online:2007-11-15 Published:2011-11-22

摘要: 从新疆高寒冻土、冷冻乳制品及生乳中分离到101株耐冷菌,利用低温β-半乳糖苷酶筛选模型,获得1株低温酶高产菌株L2004,根据其形态特征、生理生化特性,鉴定为短芽孢杆菌属(BrevibacillusShida,1996)。在以乳糖为主要碳源的发酵培养基中,L2004菌最适生长温度和最适产酶温度分别为20、15℃。该低温酶的最适pH值为6.5,最适作用温度为33℃,0℃相对酶活为总酶活的25%,在0~0℃范围内,具有较好的稳定性。不同金属离子对β-半乳糖苷酶活性的影响为:Mn2+>Mg2+>K+>Na+>Ca2+>Fe2+>Hg2+>Cu2+>Zn2+。Mn2+、Mg2+增强酶活,而Hg2+、Cu2+、Zn2+抑制酶活。该酶Km值为5.29mmol/L,具低温酶特性。

关键词: 低温&beta, -半乳糖苷酶, 酶学性质, 发酵, 短芽孢杆菌属

Abstract: A strain L2004 was obtained by screening model of cold-active β-galactosidase from 101 strains isolated from the sample of permafrost, refrigeration dairy products under 4 ℃. Based on morphological, physiology and biochemistry properties, the strain l2004 was identified as belonging to the genus Brevibacillus. The growth characteristics of the psychrotrophic bacterium L 2004 were studied, and the results showed that the optimal temperature for growth and enzyme production of the strain is about 20 ℃ and 15 ℃ respectively. The maximum enzyme activity occurred at pH 9 for L2004, and the optimal temperature of β-galactosidase action was about 33℃with ONPG as the substrate. β-galactosidase activity under 0 ℃ exhibited nearly 25% of the maximum activity, stimulated by Mg2+ and Mn2+, inhibited by Zn2+, Cu2+ and Hg2+. Moreover, Km of the cold-active β- galactosidase activity for ONPG from strain L2004 is of found to be 52.9 mmol/L at 30 ℃ Therefore the cold-active β- galactosidase of Brevibacillus sp. L2004 has particular advantage for producing lactose-reduced dairy at low temperature. The strain L2004 gives a maximum β-galactosidase activity of 80 U/ml in shaking flask after 48 h cultivation at 20 ℃ and 200 r/min when growing in a medium containing tryptone 37.5 g/L, soya peptone 5 g/L, lactose 6 g/L, yeast extract 4.5 g/L, KH2PO4 2.5 g/L and NaCl 7.5 g/L.

Key words: cold-active &beta, -galactosidase; enzyme property; fermentation; Brevibacillus;