Development and application of a most probable number-PCR assay to quantify flagellate populations in soil samples

TY - JOUR

T1 - Development and application of a most probable number-PCR assay to quantify flagellate populations in soil samples

AU - Fredslund, Line

AU - Ekelund, Flemming

AU - Jacobsen, Carsten Suhr

AU - Johnsen, Kaare Eske

PY - 2001

Y1 - 2001

N2 - This paper reports on the first successful molecular detection and quantification of soil protozoa. Quantification of heterotrophic flagellates and naked amoebae in soil has traditionally relied on dilution culturing techniques, followed by most-probable-number (MPN) calculations. Such methods are biased by differences in the culturability of soil protozoa and are unable to quantify specific taxonomic groups, and the results are highly dependent on the choice of media and the skills of the microscopists. Successful detection of protozoa in soil by DNA techniques requires (i) the development and validation of DNA extraction and quantification protocols and (ii) the collection of sufficient sequence data to find specific protozoan 18S ribosomal DNA sequences. This paper describes the development of an MPN-PCR assay for detection of the common soil flagellate Heteromita globosa, using primers targeting a 700-bp sequence of the small-subunit rRNA gene. The method was tested by use of gnotobiotic laboratory microcosms with sterile tar-contaminated soil inoculated with the bacterium Pseudomonas putida OUS82 UCB55 as prey. There was satisfactory overall agreement between H. globosa population estimates obtained by the PCR assay and a conventional MPN assay in the three soils tested.

AB - This paper reports on the first successful molecular detection and quantification of soil protozoa. Quantification of heterotrophic flagellates and naked amoebae in soil has traditionally relied on dilution culturing techniques, followed by most-probable-number (MPN) calculations. Such methods are biased by differences in the culturability of soil protozoa and are unable to quantify specific taxonomic groups, and the results are highly dependent on the choice of media and the skills of the microscopists. Successful detection of protozoa in soil by DNA techniques requires (i) the development and validation of DNA extraction and quantification protocols and (ii) the collection of sufficient sequence data to find specific protozoan 18S ribosomal DNA sequences. This paper describes the development of an MPN-PCR assay for detection of the common soil flagellate Heteromita globosa, using primers targeting a 700-bp sequence of the small-subunit rRNA gene. The method was tested by use of gnotobiotic laboratory microcosms with sterile tar-contaminated soil inoculated with the bacterium Pseudomonas putida OUS82 UCB55 as prey. There was satisfactory overall agreement between H. globosa population estimates obtained by the PCR assay and a conventional MPN assay in the three soils tested.

U2 - 10.1128/AEM.67.4.1613-1618.2001

DO - 10.1128/AEM.67.4.1613-1618.2001

M3 - Journal article

C2 - 11282613

SN - 0099-2240

VL - 67

SP - 1613

EP - 1618

JO - Applied and Environmental Microbiology

JF - Applied and Environmental Microbiology

IS - 4

ER -