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ŻYJĄCE
LECZ NIE DAJĄCE SIĘ
HODOWAĆ BAKTERIE
Hanna
Dahm, Edmund Strzelczyk
1. Wstęp.
2. Zjawisko niehodowalności wśród patogenów bakteryjnych. 3. Nie
dające się hodować bakterie
glebowe. 3.1. Przesączalność, budowa komórki a hodowalność
bakterii glebowych. 3.2. Przesączalność a
metaboliczna aktywność. 4. Reakcja bakterii na głodzenie.
5. Molekularne interpretacje niehodowalności
bakterii. 6. Czynniki wpływające na wyniki testów na
hodowalność bakterii. 7. Podsumowanie
Viable
but nonculturable bacteria
Abstract: The stage VBNC (Viable But
Nonculturable) is a strategy assumed by microrganisms when they
are exposed to stresses of the environment. In this stage bacteria
are still viable, show the metabolic
activity and respiration but can not be shown as colony
forming units by the conventional plate
methods. The stage VBNC is usually detected both in Gram-negative
and Gram-positive soil and
water bacteria as well as in pathogenic bacteria with a
considerable clinical importance. There-fore
it is important to know whether or not the cells in the stage of
nonculturability can be still pathogenic.
Up to the date it is not known whether the VBNC is a stable
physiological stage or only a temporary
form, leading to death. Some bacteria capable to grow on the
routine laboratory media, after the stress, for instance starvation, stop to grow in vitro but still show features of living cells, i.e.
metabolic activity and maintaining structures.
Factors affecting the nonculturability of bacteria can be
lethal or sublethal injury of the cells, adaptation
and differentiation, nutrient substrates accelerating the death,
lysogenic bacteriophages. Classical
methods for determinating viability status of bacteria arê
time consuming. Molecular methods offer speed, sensitivity
and specificity. Both DNA and RNA have been analysed using
molecular amplification methods such as polymerase chain reaction
(PCR), reverse transcriptase PCR (RT-PCR)
and nucleic acid sequence-based amplification (NASBA). However due
to the variable persistence of nucleic acid in post-death cells,
the relationship between presence of DNA and RNA and viability is
not clear-cut.
1. Introduction.
2. Occurence of nonculturability among pathogenic bacteria.
3. Nonculturable soil bacteria. 3.1. Filterability, cell
constituents and culturability. 3.2. Filterability and metabolic
activity. 4. The
starvation response of bacteria. 5. Molecular interpretation
of nonculturability of bacteria. 6. Factors
influencing the results of tests on the culturability of the
bacteria. 7. Conclusions
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