Characterization of a bacteriocin, Thermophilin 1277, produced by Streptococcus thermophilus SBT1277.

AIMS

To assess the inhibitory activity and the influence of culture condition on the growth and bacteriocin, Thermophilin 1277, production by Streptococcus thermophilus SBT1277.

METHODS AND RESULTS

Thermophilin 1277, which was produced by S. thermophilus SBT1277, showed an antimicrobial activity against several lactic acid bacteria and food spoilage bacteria including Clostridium butylicum, C. sprogenes and Bacillus cereus. Thermophilin 1277 was inactivated by proteinase K. Heating treatment did not affect the antimicrobial activity. The partially purified Thermophilin 1277 had an apparent molecular mass of 3.7 kDa. N-terminal sequence analysis revealed 15 amino acid residues that correspond with amino acid sequence of the lantibiotics bovicin HJ50 produced by Streptococcus bovis HJ50. The effects of culture condition for the bacteriocin production by S. thermophilus SBT1277 were studied. During the batch fermentation, Thermophilin 1277 was produced in M17 broth, but no bacteriocin production occurred in the sucrose-tryptone (ST) broth. Bacteriocin production was detected in pH controlled ST broth at pH values of 5.5-6.5.

CONCLUSIONS

Thermophilin 1277 production from S. thermophilus strain depended on the culture conditions. Some characters and N-terminal amino acid sequence of Thermophilin 1277 differed from bacteriocins produced by S. thermophilus reported previously.

SIGNIFICANCE AND IMPACT OF THE STUDY

Streptococcus thermophilus SBT1277 or its bacteriocin which has a wide inhibitory spectrum has a potential use as a biopreservative in dairy products.