title: Identification and partial characterization of tochicin, a bacteriocin offduced by Bacillus thuringiensis subsp tochigiensis.
abstract: Bacillus thuringiensis subsp tochigiensis HD868 was identified as a bacteriocin producer which exhibited a bactericidal effect against closely related species. This bacteriocin designated as tochicin, was partially purified by 75% ammonium sulfate precipitation followed by subsequent dialysis. This partially purified tochicin showed a narrow antibacterial spectrum of activity against most of 20 typical B. thuringiensis strains and a strain of B. cereus, but not against other bacteria and yeasts tested. The antibacterial activity of tochicin on sensitive indicator cells disappeared completely by proteinase K treatment (1 mg ml-1), which indicates its proteinaceous nature. Tochicin was very stable throughout the range of pH 3.0-9.0 and was relatively heat-stable at 90 degrees C, but bacteriocin activity was not detected after boiling for 30 min. The relationship between cell growth and bacteriocin production was studied in a semi-defined medium. Tochicin activity was detected at the mid-log growth phase, reached the maximum at the early stationary phase, but decreased after the stationary phase. Direct detection of tochicin activity on sodium dodecyl sulfate-polyacrylamide gel suggested it has an apparent molecular mass of about 10.5 kDa. Tochicin exhibited a bactericidal activity against B. thuringiensis subsp thompsoni HD522 in phosphate buffer (pH 7.0).
authors.affiliation: Bioprocess Engineering Division, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Taejon, Korea.
authors.forename: H D
authors.initials: HD
authors.lastname: Paik
authors.forename: S S
authors.initials: SS
authors.lastname: Bae
authors.forename: S H
authors.initials: SH
authors.lastname: Park
authors.forename: J G
authors.initials: JG
authors.lastname: Pan
mesh_terms: D001413:Bacillus thuringiensis / Q000378:metabolism*; D001430:Bacteriocins / Q000302:isolation & purification*; D004591:Electrophoresis, Polyacrylamide Gel; D006863:Hydrogen-Ion Concentration; D013696:Temperature
chemical_list: D001430:Bacteriocins