奶酪中高产β-半乳糖苷酶菌株的筛选及发酵条件的优化

Screening of High-yieldβ-Galactosidase Strains in Cheese and Optimization of Fermentation Conditions

以新疆哈萨克族奶酪样品为原料,通过蓝白斑筛选找到9株产β-半乳糖苷酶的菌株。经过摇瓶发酵测定β-半乳糖苷酶的水解活性,筛选出一株酶活力较高的菌株y-2,经鉴定为马克斯克鲁维酵母。通过研究温度、pH、破壁时间、乳糖浓度、金属离子和接种量6个参数对这株菌酶活的影响,以优化合成培养基中β-半乳糖苷酶的产生。通过单因素试验进行响应面法回归统计分析,结果表明,在温度为37℃,pH为7,破壁时间为5min,K+是促生长因子且浓度为0.001g/L,乳糖浓度为10%,接种量为4%时马克斯克鲁维酵母产生的β-半乳糖苷酶活性最高。

Using Xinjiang Kazakh cheese samples as the raw materials,9 strains producingβ-galactosidase are found through blue-white screening.The hydrolytic activity ofβ-galactosidase is measured by shake-flask fermentation,and a strain y-2 with high enzyme activity is selected and identified as Kluyveromyces marxianus.By studying the influence of temperature,pH,wall breaking time,lactose concentration,metal ions and inoculation amount on the enzyme activity of the strain,the production ofβ-galactosidase in the synthetic medium is optimized.The regression statistical analysis of response surface method is conducted through single factor experiment.The results show that the activity ofβ-galactosylase produced by Kluyveromyces marxianus is the highest at 37℃,pH 7,wall breaking time 5 min,K+as a growth factor at the concentration of 0.001 g/L,10%lactose and 4%inoculation amount.