Screening and identification of Nisin producing strains Available to Purchase

With fresh Chinese cabbage leaves as material, 0.004% bromocresol purple and 1500 IU/mL Nisin standards were added into modified GM17 medium, saccharose was used as the only carbon source, spherical strain that was Nisin-tolerate, acid-producing and Gram positive was obtained. Oxford Cup method of inhibition zone and 16S rDNA were used to identify it, and it was named L-217. By verifying the thermal stability of the bacteriostatic substance in the fermentation broth, it was detected to have good thermal stability under low pH condition. Then, the bacteriostatic substance in the fermentation broth was concentrated and purified by macroporous adsorption resin, and high performance liquid chromatography (HPLC) was used to compare the purified liquid with Nisin standards. Finally, the bacteriostatic substance was confirmed as Nisin. The Nisin-producing Lactococcus lactis was obtained.