Low doses of diarrhoeagenic E. coli induce enhanced monocyte and mDC responses and prevent development of symptoms after homologous rechallenge.

The experimental challenge with attenuated enterotoxigenic E. coli strain E1392/75-2A prevents diarrhea upon a secondary challenge with the same bacteria. A dose-response pilot study was performed to investigate which immunological factors are associated with this protection.

Use of propidium monoazide for selective profiling of viable microbial cells during Gouda cheese ripening.

DNA based microbial community profiling of food samples is confounded by the presence of DNA derived from membrane compromised (dead or injured) cells. Selective amplification of DNA from viable (intact) fraction of the community by propidium monoazide (PMA) treatment could circumvent this problem. Gouda cheese manufacturing is a proper model to evaluate the use of PMA for selective detection of intact cells since large fraction of membrane compromised cells emerges as a background in the cheese matrix during ripening.

Multifactorial diversity sustains microbial community stability.

Maintenance of a high degree of biodiversity in homogeneous environments is poorly understood. A complex cheese starter culture with a long history of use was characterized as a model system to study simple microbial communities. Eight distinct genetic lineages were identified, encompassing two species: Lactococcus lactis and Leuconostoc mesenteroides.

Indigenous and environmental modulation of frequencies of mutation in Lactobacillus plantarum.

Reliability of microbial (starter) strains in terms of quality, functional properties, growth performance, and robustness is essential for industrial applications. In an industrial fermentation process, the bacterium should be able to successfully withstand various adverse conditions during processing, such as acid, osmotic, temperature, and oxidative stresses. Besides the evolved defense mechanisms, stress-induced mutations participate in adaptive evolution for survival under stress conditions.

Functional analysis of promoters in the nisin gene cluster of Lactococcus lactis.

The promoters in the nisin gene cluster nisABTCIPRKFEG of Lactococcus lactis were characterized by primer extension and transcriptional fusions to the Escherichia coli promoterless beta-glucuronidase gene (gusA). Three promoters preceding the nisA, nisR, and nisF genes, which all give rise to gusA expression in the nisin-producing strain L. lactis NZ9700, were identified.