TY - JOUR

T1 - Cereulide formation by Bacillus weihenstephanensis and mesophilic emetic Bacillus cereus at temperature abuse depends on pre-incubation conditions

AU - Thorsen, Line

AU - Budde, Birgitte Bjørn

AU - Henrichsen, Lars

AU - Martinussen, Torben

AU - Jakobsen, Mogens

N1 - Food Micro 2008 “Evolving Microbial Food Safety and Quality” 1–4 September 2008, Aberdeen, Scotland, UK

PY - 2009

Y1 - 2009

N2 - Emetic toxin (cereulide) formation was recently identified in a psychrotolerant species, Bacillus weihenstephanensis[Thorsen, L., Hansen, B.M., Nielsen, K.F.,Hendriksen, N.B., Phipps, R.K., Budde, B.B., 2006. Characterization ofemetic Bacillus weihenstephanensisis, a new cereulide-producing bacterium. Applied and EnvironmentalMicrobiology, 72, 5118-5121.]. Although recent findings indicated B. weihenstephanensis as a cereulide producer only limited information is available regarding environmental conditions affecting cereulide production. In the present study a model agar system was used to compare cereulide production during surface growth of B. weihenstephanensis MC67, and twowell known mesophilic cereulide producing Bacillus cereus strains, NC7401 and NS117. Cereulide production was quantified by use of Liquid-Chromatography Mass Spectrometry/Mass Spectrometry. Cereulide production of B. weihenstephanensis MC67 occurred in stationary growth phase, as previously observed for B. cereus, and biomass formation and cereulide formation showed a linear correlation. During incubation at 5 °C for 1, 2 and 3 weeks growth was inhibited and as a consequence no detectable cereulide production occurred for any of the three strains. Similar resultswere obtained for the mesophilic B. cereus strains when incubated at 8 °C, whereas B. weihenstephanensis MC67 grew to stationary phase and produced 0.002 µg cereulide/cm2 agar surface in 1 week. Raising the temperature from 5 °C to 25 °C for 24 h after 1 week of incubation resulted in growth to stationary phase and production of variable levels of cereulide. B. weihenstephanensis MC67 produced 6.18 µg cereulide/cm2, B. cereus NS117 0.91 µg cereulide/cm2 and B. cereus NC7401 0.09 µg cereulide/cm2. Similar levels of cereulidewas produced by the mesophilic strains when raising the temperature from 8 °C (instead of from 5 °C) to 25 °C for 24 h, while a considerably lower level was produced by B. weihenstephanensis MC67 (0.10 µg cereulide /cm2). If the temperature was raised from 5 °C and 8 °C to 25 °C for 24 h after an increased incubation time for 2 and 3 weeks, all three strains produced considerably less cereulide. B. weihenstephanensis MC67 produced 100-6000 times less and the mesophilic B. cereus strains produced 9-40 times less cereulide. These results can partly be explained by differences in the growth at the temperature abuse.Effect of chill storage on cereulide production at temperature abuse has not been investigated previously. Results of the present study indicate that storage at 5 and 8 °C will not lead to emetic intoxications, however the time at, and choice of chill temperature will determine the amount of cereulide produced in a temperature abuse situation. These results are of relevance for the safety of chilled foods of extended durability.

AB - Emetic toxin (cereulide) formation was recently identified in a psychrotolerant species, Bacillus weihenstephanensis[Thorsen, L., Hansen, B.M., Nielsen, K.F.,Hendriksen, N.B., Phipps, R.K., Budde, B.B., 2006. Characterization ofemetic Bacillus weihenstephanensisis, a new cereulide-producing bacterium. Applied and EnvironmentalMicrobiology, 72, 5118-5121.]. Although recent findings indicated B. weihenstephanensis as a cereulide producer only limited information is available regarding environmental conditions affecting cereulide production. In the present study a model agar system was used to compare cereulide production during surface growth of B. weihenstephanensis MC67, and twowell known mesophilic cereulide producing Bacillus cereus strains, NC7401 and NS117. Cereulide production was quantified by use of Liquid-Chromatography Mass Spectrometry/Mass Spectrometry. Cereulide production of B. weihenstephanensis MC67 occurred in stationary growth phase, as previously observed for B. cereus, and biomass formation and cereulide formation showed a linear correlation. During incubation at 5 °C for 1, 2 and 3 weeks growth was inhibited and as a consequence no detectable cereulide production occurred for any of the three strains. Similar resultswere obtained for the mesophilic B. cereus strains when incubated at 8 °C, whereas B. weihenstephanensis MC67 grew to stationary phase and produced 0.002 µg cereulide/cm2 agar surface in 1 week. Raising the temperature from 5 °C to 25 °C for 24 h after 1 week of incubation resulted in growth to stationary phase and production of variable levels of cereulide. B. weihenstephanensis MC67 produced 6.18 µg cereulide/cm2, B. cereus NS117 0.91 µg cereulide/cm2 and B. cereus NC7401 0.09 µg cereulide/cm2. Similar levels of cereulidewas produced by the mesophilic strains when raising the temperature from 8 °C (instead of from 5 °C) to 25 °C for 24 h, while a considerably lower level was produced by B. weihenstephanensis MC67 (0.10 µg cereulide /cm2). If the temperature was raised from 5 °C and 8 °C to 25 °C for 24 h after an increased incubation time for 2 and 3 weeks, all three strains produced considerably less cereulide. B. weihenstephanensis MC67 produced 100-6000 times less and the mesophilic B. cereus strains produced 9-40 times less cereulide. These results can partly be explained by differences in the growth at the temperature abuse.Effect of chill storage on cereulide production at temperature abuse has not been investigated previously. Results of the present study indicate that storage at 5 and 8 °C will not lead to emetic intoxications, however the time at, and choice of chill temperature will determine the amount of cereulide produced in a temperature abuse situation. These results are of relevance for the safety of chilled foods of extended durability.

U2 - 10.1016/j.ijfoodmicro.2009.03.023

DO - 10.1016/j.ijfoodmicro.2009.03.023

M3 - Journal article

C2 - 19428136

VL - 134

SP - 133

EP - 139

JO - International Journal of Food Microbiology

JF - International Journal of Food Microbiology

SN - 0168-1605

IS - 1-2

ER -