Observation of Injured E. coli Population Resulting from the Application of High-Pressure Throttling Treatments

This study used flow cytometry (FC), epifluorescent microscopy (EM), and conventional culture media (PC) to evaluate the potential for high‐pressure throttling (HPT) to produce injury in E. coli. E. coli cells suspended at a concentration of approximately 8 log (CFU/mL) in Butterfield's phospha...

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Bibliographic Details
Published in:Journal of food science 2013-04, Vol.78 (4), p.M582-M586
Main Authors: De Lamo-Castellví, Silvia, Toledo, Romeo, Frank, Joseph F.
Format: Article
Language:English
Subjects:
Agar
Agar - chemistry
Animals
Bacteria
Biological and medical sciences
Cells
Colony Count, Microbial
conventional culture techniques
Culture Media
E coli
epifluorescent microscopy
Escherichia coli
Escherichia coli - growth & development
Flow Cytometry
Food contamination & poisoning
Food Contamination - prevention & control
Food Handling - methods
Food industries
Food Microbiology
Food Preservation - methods
Food processing industry
Food science
Fundamental and applied biological sciences. Psychology
high-pressure throttling
Hydrostatic Pressure
injured cells
Injuries
Integrity
Membranes
Microbial Viability
Microscopy, Fluorescence
Milk
Milk - microbiology
Polycarbonates
Pressure
Throttling
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Summary:This study used flow cytometry (FC), epifluorescent microscopy (EM), and conventional culture media (PC) to evaluate the potential for high‐pressure throttling (HPT) to produce injury in E. coli. E. coli cells suspended at a concentration of approximately 8 log (CFU/mL) in Butterfield's phosphate buffer and UHT skimmed milk, were treated with HPT at pressures ranging from 35 to 283 MPa. Cells were stained with SYTO 9 and propidium iodide (Live/Dead Baclight kit) to assess their membrane integrity. MacConkey and Tryptone Soy agars and a modification of the thin agar layer method were used to determine injured and non‐injured cells. PC results indicated a reduction in E. coli counts as pressure increased but no significant injured population was detected in either matrix. However, FC and EM observations indicated that the membrane integrity of a portion of the bacterial population was affected by HPT, producing different degrees of cell injury that could be sublethal. The percentage of this heterogeneous population increased with applied pressure. These results reassert the importance of understanding the potential of new processing treatments to produce sublethally‐injured bacteria, and developing appropriate detection techniques. Practical Application High‐pressure throttling could be an interesting technology to pasteurize liquid products in a continuous way. There is not a lot of information available for the researchers with this equipment. Thus, the information provided in this article will attract much attention from the scientific and industrial communities.
ISSN:0022-1147
1750-3841
DOI:10.1111/1750-3841.12074