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Purification and characterization of thermophilin T, a novel bacteriocin produced by Streptococcus thermophilus ACA-DC 0040

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Author: Aktypis, A. · Kalantzopoulos, G. · Huis Veld,in't J.H.J. · Brink, B. ten
Type:article
Date:1998
Institution: Centraal Instituut voor Voedingsonderzoek TNO
Source:Journal of Applied Microbiology, 4, 84, 568-576
Identifier: 234497
Keywords: Nutrition · Amylase · Bacteriocin · Proteinase · Thermophilin t · Unclassified drug · Bactericidal activity · Clostridium sporogenes · Gel filtration chromatography · Lactococcus · Molecular weight · Nonhuman · Polyacrylamide gel electrophoresis · Protein analysis · Protein purification · Streptococcus thermophilus · Ultrafiltration · Bacteriocins · Cheese · Electrophoresis, Polyacrylamide Gel · Food Microbiology · Hydrogen-Ion Concentration · Lactococcus · Streptococcus · Temperature · Time Factors · Clostridium sporogenes · Lactococcus · Lactococcus lactis subsp. cremoris · Posibacteria · Streptococcus thermophilus

Abstract

ACA-DC 0040 produced an antimicrobial agent, which was named thermophilin T, active against several lactic acid bacteria strains of different species and food spoilage bacteria, such as Clostridium sporogenes C22/10 and Cl. tyrobutyricum NCDO-1754. The crude antimicrobial compound is sensitive to proteolytic enzymes and α-amylase, heat-stable (100 °C for 30 min), resistant to pH exposure at pH 1-12 and demonstrates a bactericidal mode of action against the sensitive strain Lactococcus cremoris CNRZ-117. The production of bacteriocin was optimized approximately 10-fold in an aerobic fermenter held at constant pH 5.8 and 6.2. Ultrafiltration experiments with culture supernatant fluids containing the bacteriocin, and further estimation of molecular weight with gel filtration chromatography, revealed that bacteriocin in the native form has a molecular weight in excess of 300 kDa. SDS-gel electrophoresis of partially purified thermophilin T showed that bacteriocin activity was associated with a protein band of approximately 2.5 kDa molecular mass.