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Appl. Environ. Microbiol., Oct 1995, 3639-3644, Vol 61, No. 10
AJ Alvarez, MP Buttner and LD Stetzenbach
The PCR technique has potential for use in detection of low concentrations
of airborne microorganisms. In this study, the sensitivity of PCR and its
susceptibility to environmental interference were assessed with Escherichia
coli DH1 as the target organism. Air samples, containing environmental
bioaerosols, were collected with AGI- 30 samplers and seeded with E. coli
DH1 cells. Parallel studies were performed with cells seeded into the
sampler prior to collection of air samples to determine the effects of
environmental inhibition and sampling stress on the PCR assay. Baseline
studies were also performed without environmental challenge or sampling
stress to compare two protocols for cell lysis, solid phase and
freeze-thaw. Amplification of a plasmid target sequence resulted in a
detection limit of a single bacterial cell by the freeze-thaw and
solid-phase methods within 5 and 9 h, respectively. With a genomic target,
the sensitivity of the solid- phase method was 10-fold lower than that of
freeze-thaw. Samples which contained 10(3) to 10(4) CFU of environmental
organisms per m3 inhibited amplification; however, a 1/10 dilution of these
samples resulted in successful amplifications. No difference in sensitivity
of the PCR assay was obtained as a result of sampling stress, although a
10-fold decrease in culturability was observed. A field validation of the
protocol with genomic primers demonstrated the presence of airborne E. coli
and/or Shigella spp. in outdoor samples. This study indicates that the PCR
method for detection of airborne microorganisms is rapid and sensitive and
can be used as an alternative method for air quality monitoring.
Copyright © 1995, American Society for Microbiology
PCR for bioaerosol monitoring: sensitivity and environmental interference
Harry Reid Center for Environmental Studies, University of Nevada, Las Vegas 89154-4009, USA.
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