The invention relates to a preparation method and application of a recombinant
lactococcus lactis. The invention is characterized in that the surface immunogenic
protein (Sip) of
tilapia-source
streptococcus agalactiae is intracellularly or secretorily expressed in
lactococcus lactis cells, vectors which are used for the
recombinant expression of the Sip are pNZ8124 and pNZ8148 respectively,
signal peptide segments are removed from Sip
gene segments inserted into the vectors, and
histidine sequence tags are added to the Sip
gene segments, the recombinant
protein is induced to be expressed by
Nisin, the optimum induction condition is 4h of induction by 100ng / mL of
Nisin, the optimum
oral immunization concentration is 2.24*10<10>CFU / mL, and the oral dosage is 100 mu L. The recombinant
lactococcus lactis disclosed by the invention which is applied in
lactobacillus living vector vaccines against
tilapia streptococcus agalactiae has the advantages of wide
serotype coverage, direct
oral administration, high safety, easiness in operation, easy large-scale
herd immunity, good immune effect and the like.