Antimicrobial activity of lactobacilli: preliminary characterization and optimization of production of acidocin B, a novel bacteriocin produced by Lactobacillus acidophilus M46.
Approximately 1000 lactobacillus strains were isolated and screened for the production of antimicrobial activity, using a target panel of spoilage organisms and pathogens. Only eight positive strains were found; two of these were studied in more detail. Lactobacillus salivarius M7 produces the new broad spectrum bacteriocin salivaricin B which inhibits the growth of Listeria monocytogenes, Bacillus cereus, Brochothrix thermosphacta, Enterococcus faecalis and many lactobacilli. A new atypical bacteriocin produced by Lact. acidophilus M46, acidocin B, combines the inhibition of Clostridium sporogenes with a very narrow activity spectrum within the genus Lactobacillus and was selected for further characterization. Acidocin B is sensitive to trypsin, heat-stable (80 degrees C for 20 min) and can be extracted from the culture supernatant fluid with butanol. Native acidocin B occurs as a large molecular weight complex (100 kDa), while with SDS-PAGE the partly purified activity migrates as a peptide of 2.4 kDa. Optimization of the cultivation conditions resulted in an eightfold increase of the amount of acidocin B produced during growth. Growth is not necessary for acidocin B production; washed producer cells can synthesize the bacteriocin in a chemically defined production medium. The application potential of acidocin B is discussed.
TNO Nutrition and Food Research, Department of Microbiology, Zeist, The Netherlands.
B
B
ten Brink
M
M
Minekus
J M
JM
van der Vossen
R J
RJ
Leer
J H
JH
Huis in't Veld
D001430:Bacteriocins / Q000096:biosynthesis* / Q000302:isolation & purification; D004591:Electrophoresis, Polyacrylamide Gel; D005516:Food Microbiology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007779:Lactobacillus acidophilus / Q000378:metabolism*; D008970:Molecular Weight; D014357:Trypsin / Q000494:pharmacology
D001430:Bacteriocins; C090262:acidocin B protein, Lactobacillus; D014357:Trypsin