About this Research Topic
Microorganisms, like all living organisms, naturally respond to changing environmental conditions. They display a remarkable ability to adapt to certain physical and chemical stresses in their environment. Survival mechanisms are activated following the detection of environmental signals and generate a complex adaptive response that leads to a state of tolerance and thus survival under sub-optimal or even sub-lethal conditions. When the environmental conditions threaten their survival or prevent them from living in optimal conditions, the cells are described as stressed. This notion of stress plays a fundamental role in the survival of microorganisms in foodstuff.
The viable but non-culturable (VBNC) state, a unique state in which a number of bacteria respond to adverse circumstances, was first discovered in 1982. The VBNC state, which has been extensively studied in bacteria, is characterized by an inability of the cells to grow on culture media, even though they are still viable and maintain a detectable metabolic activity. This state is reversible upon return of favorable conditions. Various environmental factors can induce entry into VBNC state including temperature, the physiological age of the culture, salinity, the oxygen content, light, and ventilation.
Most studies on VBNC cells have focused on pathogenic bacteria. Almost 70 bacterial species have been described as being able to enter into a VBNC state, Gram-positive (e.g. Listeria monocytogenes, Enterococcus, Micrococcus luteus) and Gram-negative (e.g. Escherichia coli, Vibrio cholerae, Vibrio vulnificus, Legionella pneumophila, Campylobacter jejuni, Salmonella enterica, Pseudomonas aeruginosa, Helicobacter pylorii). In contrast, the VBNC state has received much less attention in other microorganisms, such as yeast and non-pathogenic foodborne bacteria.
In addition, just as all of us are challenged by the formation of biofilm on our teeth, a challenge that food processors and their sanitation teams face is the formation of biofilms on food equipment surfaces. Food manufacturing plants, particularly sanitation and food safety/quality personnel, will want to recognize this potential hazard related to sanitation and that biofilms can have a profound impact on the safety and quality of their products.
Biofilm formation can contaminate products through the introduction of pathogenic microorganisms or spoilage bacteria. They are difficult to remove, are often resistant to normal sanitation procedures and can result in other detrimental process effects. Even when a food surface appears to be clean, the presence of biofilms is a potential hazard that must be eliminated and prevented from reoccurring. Before this can be done, it is important to understand what a biofilm is and how it is formed.
This Research Topic aims to provide an avenue for the dissemination of recent advances within the “VBNC” and “biofilms” fields, including:
i) novel knowledge on induction and resuscitation mechanisms of VBNC microorganisms under food processing conditions and their biological characteristics,
ii) novel knowledge on mechanisms of biofilm formation and biofilm architecture under food processing conditions, and
iii) novel strategies and methods for the control of VBNC microorganisms and biofilms in food industrial settings.
Keywords: Food microbiology, Viable but nonculturable state, Biofilm, Formation, Food safety and control
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