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The "Phoenix Phenomenon" During Resuscitation of Fungi in Foods 1, 2
John A Koburger1, Richard A Dargan1
1Food Science and Human Nutrition, University of Florida, Gainesville, Florida 32611.
Abstract:
During attempts to increase recovery of fungi from foods by providing for a period of resuscitation before plating, a rapid decrease in cell numbers was observed with certain samples. This decrease in numbers occurred for about the first 12 h of incubation followed by a gradual increase in viable cell count thereafter. This pattern of growth has been termed the "Phoenix Phenomenon" and is associated with repair of metabolic injury. Numerous attempts to overcome this decrease in numbers by altering resuscitation menstrua and plating media were not successful.
Insights
Certain food samples showed a rapid decrease in fungal cell numbers during resuscitation, followed by a gradual increase. This "Phoenix Phenomenon" indicates metabolic injury repair in fungi, which current methods could not overcome.
Area of Science:
- Microbiology
- Food Science
- Cellular Physiology
Background:
- Fungal recovery from foods is crucial for safety and quality assessment.
- Standard methods may not account for stressed or injured fungal cells.
- Resuscitation aims to revive viable but non-culturable (VBNC) or metabolically impaired fungi.
Purpose of the Study:
- To investigate an observed initial decrease in fungal cell counts during resuscitation.
- To characterize the phenomenon of initial cell reduction followed by recovery.
- To identify potential strategies to improve fungal recovery from stressed food samples.
Main Methods:
- Incubation of fungal samples from food sources under specific resuscitation conditions.
- Monitoring of viable fungal cell counts over time (e.g., 12-hour intervals).
- Systematic variation of resuscitation media and plating techniques.
Main Results:
- A consistent pattern of rapid decrease in viable fungal cell numbers within the first 12 hours of resuscitation was observed.
- Following the initial decline, a gradual increase in cell counts indicated fungal recovery.
- This transient reduction in cell numbers was termed the "Phoenix Phenomenon".
- Attempts to modify resuscitation and plating media did not prevent the initial cell decrease.
Conclusions:
- The "Phoenix Phenomenon" is linked to the metabolic injury repair process in fungi.
- Standard resuscitation protocols may initially underestimate fungal populations due to this effect.
- Further research is needed to understand and potentially mitigate the initial cell decline for improved fungal detection in foods.