of;
Food;
Science;
and;
Technology;
Agricultural;
University;
of;
Hebei;
Baoding;
071001;
P.R.;
China;
of;
Food;
Science;
and;
Nutritional;
Engineering;
China;
Agricultural;
University;
Beijing;
100083;
P.R.;
China;
of;
Microbiology;
Chinese;
Academy;
of;
Sciences;
Beijing;
100080;
P.R.;
China;
半乳糖苷酶基因; 表达载体; 选择标记; 食品级; SDS-PAGE分析; 乳酸乳球菌; PCR扩增; PCR克隆;