Previous Article | Next Article ![]()
Appl. Environ. Microbiol., Feb 1996, 668-675, Vol 62, No. 2
BA Hales, C Edwards, DA Ritchie, G Hall, RW Pickup and JR Saunders
The presence of methanogenic bacteria was assessed in peat and soil cores
taken from upland moors. The sampling area was largely covered by blanket
bog peat together with small areas of red-brown limestone and peaty gley. A
30-cm-deep core of each soil type was taken, and DNA was extracted from
5-cm transverse sections. Purified DNA was subjected to PCR amplification
with primers IAf and 1100Ar, which specifically amplify 1.1 kb of the
archaeal 16S rRNA gene, and ME1 and ME2, which were designed to amplify a
0.75-kb region of the alpha-subunit gene for methyl coenzyme M reductase
(MCR). Amplification with both primer pairs was obtained only with DNA
extracted from the two deepest sections of the blanket bog peat core. This
is consistent with the notion that anaerobiosis is required for activity
and survival of the methanogen population. PCR products from both
amplifications were cloned, and the resulting transformants were screened
with specific oligonucleotide probes internal to the MCR or archaeal 16S
rRNA PCR product. Plasmid DNA was extracted from probe-positive clones of
both types and the insert was sequenced. The DNA sequences of 8 MCR clones
were identical, as were those of 16 of the 17 16S rRNA clones. One clone
showed marked variation from the remainder in specific regions of the
sequence. From a comparison of these two different 16S rRNA sequences, an
oligonucleotide was synthesized that was 100% homologous to a sequence
region of the first 16 clones but had six mismatches with the variant. This
probe was used to screen primary populations of PCR clones, and all of
those that were probe negative were checked for the presence of inserts,
which were then sequenced. By using this strategy, further novel methanogen
16S rRNA variants were identified and analyzed. The sequences recovered
from the peat formed two clusters on the end of long branches within the
methanogen radiation that are distinct from each other. These cannot be
placed directly with sequences from any cultured taxa for which sequence
information is available.
Copyright © 1996, American Society for Microbiology
Isolation and identification of methanogen-specific DNA from blanket bog peat by PCR amplification and sequence analysis
Department of Genetics and Microbiology, University of Liverpool, United Kingdom.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»