Genotypic and phenotypic characterization of foodborne Geobacillus stearothermophilus. (February 2015)

• Record Type: Journal Article
• Authors: Durand, Loïc; Planchon, Stella; Guinebretiere, Marie-Hélène; Carlin, Frédéric; Remize, Fabienne
• Is Part Of: Food microbiology. Volume 45:Part A(2015)
• Page Start: 103
• Page End: 110
• Publication Date: 2015-02
• Subjects: Geobacillus stearothermophilus -- Canned food spoilage -- Spore-forming bacteria -- Diversity -- M13 genetic typing; Food Microbiology -- Periodicals; Aliments -- Microbiologie -- Périodiques; Food -- Microbiology; Periodicals; Food -- Microbiology -- Periodicals; Food contamination -- Periodicals; 664.001579
• DOI: 10.1016/j.fm.2014.01.015
• Languages: English
• ISSNs: 0740-0020

Abstract

Abstract: Geobacillus stearothermophilus is the main thermophilic spore former involved in flat sour spoilage of canned foods. Three typing methods were tested and applied to differentiate strains at intra-species level: panC sequence analysis, REP-PCR and M13-PCR. panC gene was highly conserved within the studied strains, suggesting a low intra-specific diversity. This was supported by REP-PCR primary assays and M13-PCR results. M13-PCR profile analysis succeeded in differentiating six closely related groups (at 79% threshold similarity) among 127 strains from a range of spoiled canned food products and from different canneries. Phenotypic traits were investigated among 20 selected strains representing groups and origins. Ranges of growth under different temperatures (from 40 °C to 70 °C), pH (from 5.0 to 6.5), NaCl concentrations (from 1 to 5%) and sporulation conditions poorly differed between strains, but wet heat resistance of spores showed a 20-fold variation between strains. Furthermore, in this study, strains that belonged to the same M13-PCR genetic group did not share phenotypic characteristics or common origin. The work emphasizes a low diversity within the G. stearothermophilus species but data from this study may contribute to a better control of G. stearothermophilus spoilage in canned food. Highlights: 127 Geobacillus stearothermophilus strains of diverse origins were examined for diversity. M13-PCR typing showed a weak genetic diversity. Growth limits for temperature, pH and NaCl poorly differed between strains. Time to 5 log-reduction varied between <0.5 min and 12.4 min.