Viable but nonculturable bacteria in drinking water

Byrd, Jeffrey J.; Xu, Hanlin; Colwell, Rita R.

doi:10.1128/aem.57.3.875-878.1991

Cited by 225 publications

(90 citation statements)

References 13 publications

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“…The reasons why the plating efficiency of pelagic bacteria is so low are unknown. Colwell and colleagues have proposed that stress of the ocean environment may render the bacteria unculturable while remaining viable [21,22]. We hypothesize that low plating efficiency of the dominant bacteria (as in our study) may have been caused through lysis by bacteriophages entering lytic phase upon shift-up of bacteria on the culture medium [23].…”

Section: Resultsmentioning

confidence: 65%

Blooms of sequence-specific culturable bacteria in the sea

Rehnstam

Bäckman

Smith

et al. 1993

FEMS Microbiology Letters

143

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Using specific deoxyoligonucleotide probes we have discovered seasonally strong (up to ∼ 100%) dominance of bacteria hybridizing to a single probe, in near shore waters off Scripps pier (32°53′N; 117°15′W). The probes were designed from partially sequenced 16S rRNA (V3 domain) of isolated marine bacteria. The results indicate that this approach may be used for studies of bacterial populations in the marine environment. We have shown that a number of genotypes that at times are dominant in the natural assemblages are culturable (and not, ‘viable‐but‐unculturable’). Additionally, our data suggests that the discrepancy between viable counts and direct counts in sea water samples can be explained by low plating efficiency.

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Section: Resultsmentioning

confidence: 65%

Blooms of sequence-specific culturable bacteria in the sea

Rehnstam

Bäckman

Smith

et al. 1993

FEMS Microbiology Letters

143

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“…However, aggregates were never observed under the microscope in the leaf homogenate used for plate counts. VBNC bacteria have previously been detected in microbiologically-controlled systems such as autoclaved or filtered water (Byrd et al 1991;Besnard et al 2000b) and in sterilized irradiated seeds (Pedersen and Leser 1992;Grey and Steck 2001).…”

Section: Discussionmentioning

confidence: 99%

Viable but non-culturableListeria monocytogeneson parsley leaves and absence of recovery to a culturable state

Dreux

Albagnac

Fédérighi³

et al. 2007

Journal of Applied Microbiology

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Aims: To investigate the presence of viable but non‐culturable Listeria monocytogenes during survival on parsley leaves under low relative humidity (RH) and to evaluate the ability of L. monocytogenes to recover from VBNC to culturable state under satured humidity. Methods and Results: Under low RH (47–69%) on parsley leaves, the initial number of L. monocytogenes populations counted on non selective media (109 L. monocytogenes per leaf on TSA) was reduced by 6 log10 scales in 15 days, whereas number of viable L. monocytogenes counted under the microscope was reduced by 3–4 log10 scales, indicating the presence of VBNC cells. This was demonstrated on three L. monocytogenes strains (EGDe, Bug 1995 and LmP60). Changing from low to 100% RH permitted an increase of the culturable counts of L. monocytogenes and this growth was observed only when residual culturable cells were present. Moreover, VBNC L. monocytogenes inoculated on parsley leaves did not become culturable after incubation under 100% RH. Conclusions: Dry conditions induced VBNC L. monocytogenes on parsley leaves but these VBNC were likely unable to recover culturability after transfer to satured humidity. Significance and Impact of Study: Enumeration on culture media presumably under‐estimates the number of viable L. monocytogenes on fresh produce after exposure to low RH.

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“…This state has been described as viable but non-culturable (VBNC). Certain enteric bacteria can retain their pathogenicity whilst VBNC [5,6]. A recent study showed that intact S. typhimurium cells reside in non-sterile soil for long periods of time in spite of apparent rapid die-o¡ according to viable counts on selective agar [7].…”

Section: Introductionmentioning

confidence: 99%

Quantitative molecular detection of Salmonella typhimurium in soil and demonstration of persistence of an active but non-culturable population

Marsh

1998

FEMS Microbiology Ecology

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Several methods were used to study survival of Salmonella typhimurium LT2 in soil. An ion exchange resin-based extraction method was used to concentrate biomass from soil, from which DNA was extracted in order to quantify a Salmonella-specific sequence by a quantitative polymerase chain reaction (QPCR). S. typhimurium LT2 was detected at a minimum density of 10 Q cells g 3I in non-sterile soil, and the method proved to be specific for this organism in microcosm experiments. Non-sterile soil microcosms were inoculated with S. typhimurium LT2 at 10 U cfu g 3I dry soil and survival monitored at three matric potentials. Viable counts on XLD indicated a rapid decline in cell density over 54 days, whereas direct counts of active cells using the respiration-sensitive dye 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) remained relatively constant. XLD did not underestimate culturable cells in comparison to non-selective agar. QPCR revealed that the number of salmonella targets (H-li) remained constant up to day 13. After that time, a decrease occurred, corresponding to that of the plate counts, due to an increase in resistance of the cells to lysis, as incorporation of a lysozyme step into the DNA extraction method allowed more efficient DNA extraction. This resulted in a constant QPCR signal over 54 days which correlated with direct, active cell counts. QPCR showed H-li was present at levels only slightly lower than those at day 0. There was no difference in survival between the three different moisture regimes. Direct CTC counts of S. typhimurium LT2 in the soil microcosms confirmed that intact cells were present in a metabolising state after 54 days in non-sterile soil, indicating a significant proportion of uncultured but active cells. z

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Viable but nonculturable bacteria in drinking water

Cited by 225 publications

References 13 publications

Blooms of sequence-specific culturable bacteria in the sea

Blooms of sequence-specific culturable bacteria in the sea

Viable but non-culturableListeria monocytogeneson parsley leaves and absence of recovery to a culturable state

Quantitative molecular detection of Salmonella typhimurium in soil and demonstration of persistence of an active but non-culturable population

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