Page 37 - FoodFocusThailand No.164 November 2019

STRONG QC & QA

Nucleic acid remaining inside the microbial cells Nucleic acids releasing from
Techniques/methods microbial cells or nucleic acids
Dead cells VBNC Injured cells Normal living in food
cells
Molecular techniques + + + + +
Standard method: developing - - +/- + -
microbes in culture media
Note: + detectable – undetectable
เอกสารอ้างอิง/Reference
microbes. However, to use molecular Siele, C., L. Dan, U. Mieke, R. Pierre, R. Paul, R. V. Marc, C. Luca and D. John. 2014. Molecular methods in
techniques for foodborne pathogen analysis, food safety microbiology: Interpretation and implications of nucleic acid detection. doi: 10.1111/1541-
certain limitation should be concerned, such 4337.12072.
as some genetic substances characterize
stability even in the process of food processing
that are used to destroy living microbial cells.
Therefore, the existence of genetic material
in food in such condition can affect the
accuracy of the analyzing interpretation of the
targeting microbes just as genetic material are
synthesized from the dead targeting microbial
cells. Also, the cost of chemicals, equipment
and tools are relatively high, together with an
inhibition of the synthesis of target genetic
material from various components in food, and
low initial amount of target microbes contained
in foods.
The limitations of such molecular
techniques, for instance, the synthesis of
genetic material from dead microbial cells in
food could be resolved by culturing target
microbes under optimum conditions. That way
the number of living microbial cell target can
be increased sufficiently before extracting the
genetic material, in conjunction with the design
of messenger RNA (mRNA) analysis of target
microbes, or the use of chemical agents like
Ethidium monoazide or Propidium monoazide
in the analyzing process to differentiate living
genetic material from dead microbial cells.

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