Screening Of Lactic Acid Bacteria With Potential To Reduce Antigenic Response Of β-lactoglobulin And Study On Its Characteristics

The whey proteinβ-lactoglobulin, which accounts for 43.6%-50.0% whey protein in total protein and 2-4g/L in skim milk, is a kind of special protein synthesized by the epidermic cell of galactophore in ruminants. The naturalβ-lactoglobulin is the major allergen in milk for children and infants, which badly blocks the absorbtion of milk protein for infants. A strain WPC09 with high ability to reduceβ-lg antigenity was isolated from the raw milk. The morphological, physiological characteristics and 16s rDNA sequence of strain WPC09 were studied and the results showed that characteristics of this strain were essentially consistent with Lactobacillus casei. The optimum growth temperature of L. casei WPC09 is 37℃, as to the pH, the optimum is 6.5.With the 1%(v/v) cell of L. casei WPC09 at 37℃for 24h in milk, the reduction rate ofβ-lactoglobulin antigenity was 92.0%. At the same condition,β-lactoglobulin antigenity of MRS which was added withβ-lactoglobulin reduced 74.1%, it also has the high ability.The supernatant and intact cells of L. casei WPC09 also have the ability to reduceβ-lactoglobulin antigenity, so we supposed that it was the combined action of growth and product of metabolism.L. casei WPC09 has the high ability to reduce antigenic response ofβ-lactoglobulin, so we studied the drug sensitivity, tolerance to acid, bible salt and NaCl. The resistance for antibiotic of L. casei WPC09 indicates that it is sensitive to the most of the antibiotic in the 26 kinds of common antibiotic. The livability of L. casei WPC09 in pH3.0 for 1h is 85.11%. And the maximal growth concentration of bible salt is 0.09%, and that of the NaCl is 10%.