abstract book - Clostridia

EFFECT OF CARBON DIOXIDE ON NEUROTOXIN GENE
EXPRESSION IN NON-PROTEOLYTIC CLOSTRIDIUM BOTULINUM
TYPES B AND E
I. Artin 1,2,3 , A.T. Carter 2 , E. Holst 3 , M. Lövenklev 1 , D.R. Mason 2 , M.W.
Peck 2 , and P. Rådström 1
1 Applied Microbiology, Lund Institute of Technology, Lund University,
SE-221 00 Lund, Sweden, 2 Institute of Food Research, Norwich
Research Park, Colney, Norwich, NR4 7UA, UK, 3 Division of Medical
Microbiology, Department of Laboratory Medicine, Lund University, SE-
223 62 Lund, Sweden.
When developing new food products and manufacturing solutions, it is
important to consider not only the occurrence and quantity of
pathogens in the food chain, but how the processing and subsequent
storage and handling will affect them. This is especially relevant for
food designed to have a long shelf-life. Understanding the influence of
environmental factors, food preservatives, and type of packaging on
microbial growth and expression of virulence factors is very important.
Quantitative reverse transcription PCR (qRT-PCR) and enzyme-linked
immunosorbent assay (ELISA) were used to monitor neurotoxin gene
(cnt) expression and neurotoxin formation in non-proteolytic C.
botulinum types B and E. Relative gene expression varied with growth
phase in both types, reaching a maximum in late exponential and early
stationary phase.
We also found that while growth was slowed, relative cnt expression
was increased with an elevated CO 2 concentration, with five-fold
greater expression of cntB mRNA and accumulation of type B toxin at
70% CO 2 than at 10%. For type E the increase in expression at 70%
CO 2 was two-fold greater, when compared with 10% CO 2 .
In conclusion, these findings, shown with both qRT-PCR and ELISA,
sheds a new cautionary light on the potential risks of botulism
associated with non-proteolytic C. botulinum and the use of modified
atmosphere packaging.
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