D Bizani1, A P M Dominguez, A Brandelli. 1. Laboratório de Bioquímica e Microbiologia Aplicada, Departamento de Ciência de Alimentos, ICTA, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
Abstract
AIMS: To purify and to characterize the antimicrobial compound cerein 8A. METHODS AND RESULTS: Cerein 8A was isolated by ammonium sulfate precipitation, 1-butanol extraction and ion-exchange chromatography. Direct activity on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was observed. The purified substance corresponded to a 26 kDa peptide band. The native protein eluted at the void volume of Sephadex G-100, but within the included volume when a 1.5 mol l(-1) NaCl buffer was used, indicating that cerein 8A aggregates extracellularly. The antimicrobial activity was lost by treatment with proteases and heat. The ultraviolet spectrum was typical of a polypeptide and the infrared spectrum indicates that the peptide contains acyl group(s) in its structure. Intact Bacillus cereus spores were sensitive to cerein 8A at 1600 AU ml(-1). CONCLUSIONS: Cerein 8A show distinct properties from other antimicrobial peptides of B. cereus, and has a significant inhibitory effect on spores. SIGNIFICANCE AND IMPACT OF THE STUDY: The characterization of a substance active against important pathogens addresses an important aspect of food safety.
AIMS: To purify and to characterize the antimicrobial compound cerein 8A. METHODS AND RESULTS:Cerein 8A was isolated by ammonium sulfate precipitation, 1-butanol extraction and ion-exchange chromatography. Direct activity on sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE) was observed. The purified substance corresponded to a 26 kDa peptide band. The native protein eluted at the void volume of Sephadex G-100, but within the included volume when a 1.5 mol l(-1) NaCl buffer was used, indicating that cerein 8A aggregates extracellularly. The antimicrobial activity was lost by treatment with proteases and heat. The ultraviolet spectrum was typical of a polypeptide and the infrared spectrum indicates that the peptide contains acyl group(s) in its structure. Intact Bacillus cereus spores were sensitive to cerein 8A at 1600 AU ml(-1). CONCLUSIONS:Cerein 8A show distinct properties from other antimicrobial peptides of B. cereus, and has a significant inhibitory effect on spores. SIGNIFICANCE AND IMPACT OF THE STUDY: The characterization of a substance active against important pathogens addresses an important aspect of food safety.
Authors: Mary C Rea; Clarissa S Sit; Evelyn Clayton; Paula M O'Connor; Randy M Whittal; Jing Zheng; John C Vederas; R Paul Ross; Colin Hill Journal: Proc Natl Acad Sci U S A Date: 2010-04-30 Impact factor: 11.205