Genotypical and phenotypical characterization of Bacillus sporothermodurans strains, surviving UHT sterilisation

• Published in: International dairy journal 1997-06, Vol.7 (6), p.421-428
• Main Authors: Klijn, Nicolette, Herman, Lieve, Langeveld, Leo, Vaerewijck, Mario, Wagendorp, Arjen A., Huemer, Ingrid, Weerkamp, Anton H.
• Format: Article
• Language: English
• Subjects: 16S rRNA; Bacillus sporothermodurans; Biological and medical sciences; Food industries; Fundamental and applied biological sciences. Psychology; heat resistance; Milk and cheese industries. Ice creams; RAPD- and REP-DNA-fingerprinting; spores
• ISSN: 0958-6946; 1879-0143
• DOI: 10.1016/S0958-6946(97)00029-0

Isolates from UHT products suspected for the presence of highly heat resistant sporeforming bacteria obtained from different European countries and sporeforming bacteria isolated from heated raw milk were identified by 16S rRNA sequence analysis, RAPD- and REP-patterns. The isolates from the UHT products formed a very homogeneous group and based on the 16S rRNA sequence they belong to the recently described new species Bacillus sporothermodurans. Similar RAPD or REP-PCR patterns could be observed for all isolates from non-sterile UHT-milk, while other bacilli from milk had clearly different patterns. The heat resistance of the spores of B. sporothermodurans in the UHT region was high, less than three decimal reductions in 5 s at 140 °C, in particular compared to spores of other mesophilic sporeformers and Bacillus stearothermophilus. Identification of B. sporothermodurans on phenotypic characteristics was problematic, partly because other Bacillus species with similar phenotypes could be isolated from raw milk. Since 16S rRNA sequence analysis for B. sporothermodurans is complicated by the presence of multiple 16S rRNA types, it was concluded that for the rapid and reliable identification of isolates the application of RAPD or REP-PCR fingerprinting presents a most useful tool.