Quantitative real-time reverse transcription-PCR analysis reveals stable and prolonged neurotoxin cluster gene activity in a Clostridium botulinum type E strain at refrigeration temperature.
The relative expression levels of six botulinum neurotoxin cluster genes in a group II Clostridium botulinum type E strain grown at 10 or 30 degrees C were investigated using quantitative real-time reverse transcription-PCR. An enzyme-linked immunosorbent assay was used to confirm neurotoxin expression. Distinct mRNA and toxin production patterns were observed at the two temperatures. The average relative mRNA levels at 10 degrees C were higher than (ntnh and p47), similar to (botE), or lower than (orfx1, orfx2, orfx3) those at 30 degrees C. The maximum botE expression levels and average neurotoxin levels at 10 degrees C were 45 to 65% of those at 30 degrees C. The relative mRNA levels at 10 degrees C declined generally slowly within 8 days, as opposed to the rapid decline observed at 30 degrees C within 24 h. Distinct expression patterns of the six genes at the two temperatures suggest that the type E neurotoxin cluster genes are transcribed as two tricistronic operons at 30 degrees C, whereas at 10 degrees C monocistronic (botE or orfx1 alone) and bicistronic (ntnh-p47 and orfx2-orfx3) transcription may dominate. Thus, type E botulinum neurotoxin production may be involved with various temperature-dependent regulatory events. In light of group II C. botulinum type E being a dangerous food-borne pathogen, these findings may be important in terms of the safety of refrigerated packaged foods of extended durability.
Chen
Ying
Y
Centre of Excellence in Microbial Food Safety Research, Department of Food and Environmental Hygiene, Faculty of Veterinary Medicine, University of Helsinki, Finland.
Korkeala
Hannu
H
Lindén
Jere
J
Lindström
Miia
M
D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics; D001905:Botulinum Toxins / Q000096:biosynthesis* / Q000235:genetics; D047970:Clostridium botulinum type E / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D003080:Cold Temperature; D017931:DNA Primers / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D020869:Gene Expression Profiling; D023061:Gene Order; D005796:Genes; D008969:Molecular Sequence Data; D005810:Multigene Family; D012329:RNA, Bacterial / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D012034:Refrigeration; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
D001426:Bacterial Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012333:RNA, Messenger; D001905:Botulinum Toxins; C096326:botulinum toxin type E