Desiccation and heat tolerance of Enterobacter sakazakii.
OBJECTIVE
Enterobacter sakazakii is an opportunistic pathogen which has been isolated at low levels from powdered infant formulas. This study was performed to demonstrate that Ent. sakazakii is not particularly thermotolerant, but can adapt to osmotic and dry stress.


RESULTS
We determined the heat, osmotic and dry stress resistance of Ent. sakazakii. The D-value at 58 degrees C ranged from 0.39 to 0.60 min, which is comparable with that of other Enterobacteriaceae, but much lower than reported previously (Nazarowec-White and Farber 1997, Letters in Applied Microbiology 24: 9-13). However, stationary phase Ent. sakazakii cells were found to be more resistant to osmotic and dry stress than Escherichia coli, Salmonella and other strains of Enterobacteriaceae tested. Further analysis indicated that the dry resistance is most likely linked to accumulation of trehalose in the cells.


CONCLUSIONS
The high tolerance to desiccation provides a competitive advantage for Ent. sakazakii in dry environments, as found in milk powder factories, and thereby increases the risk of postpasteurization contamination of the finished product.


CONCLUSIONS
Understanding of the physiology and survival strategies of Ent. sakazakii is an important step in the efforts to eliminate this bacterium from the critical food production environments.
Breeuwer
P
P
Nestlé Research Center, Nestec Ltd, Vers-Chez-Les-Blanc, Lausanne, Switzerland. pieter.breeuwer@rdls.nestle.com
Lardeau
A
A
Peterz
M
M
Joosten
H M
HM
D015169:Colony Count, Microbial; D044083:Cronobacter sakazakii / Q000201:enzymology / Q000254:growth & development*; D003890:Desiccation; D005516:Food Microbiology; D006358:Hot Temperature; D006801:Humans; D007223:Infant; D007225:Infant Food / Q000382:microbiology*; D009997:Osmotic Pressure; D013696:Temperature; D014199:Trehalose / Q000032:analysis
D014199:Trehalose