Under these conditions, the SD selleck screening library was 1.1% (Table 2, mixed amplicons), and relative abundances varied from 18.7% to 22.0% (Table

S3 in Appendix S2). The influence of the vicinity of the peaks on LH-mcrA data was evaluated by comparing the LH-mcrA profile from the mixed amplicons with a profile generated by overlaying individual electrophoretic migrations of each clone (Fig. S1b). This resulted in an artificial profile with peak heights varying from 17.7% to 21.7% with a mean value of 20.0 ± 1.4% (Table 2, individual clones). This is the first time that the structure and diversity of archaeal communities are estimated by LH-PCR using a functional gene. One can therefore estimate simultaneously the diversity of a functional group and the relative expression level of this gene (mRNA level) from the different members of this group. Even

though T-RFLP based on the mcrA gene has already been reported as a valuable tool for this purpose find more (Lueders et al., 2001), LH-PCR is less expensive (Talbot et al., 2008), more reproducible (Mills et al., 2003) and more rapid than T-RFLP. In contrast to LH-mcrA, T-RFLP requires that PCR products are first purified and de-salted using a commercial kit followed by a restriction digestion step for several hours. The cost for T-RFLP is therefore increased by a factor of approximately 250% (ca. 3.50$ instead of 1$ per DNA sample) by comparison with LH-mcrA. Incomplete enzymatic restriction digestion may affect reproducibility in T-RFLP data (Mills et al., 2003). All those advantages LH-mcrA offers U0126 research buy are promising to assess changes in methanogenic archaeal communities

in biosystems at low cost and quickly. As suggested by LH-mcrA profiling and clone library analysis from the PFBR, the methanogenic archaeal communities in swine manure would tentatively be mainly composed of members from the Order Methanomicrobiales, which is in agreement with T-RFLP results based on the 16S rRNA gene on other swine manure samples (Talbot et al., 2009). LH-mcrA profiling suggested that the methanogenic community in the dairy manure sample would mainly be composed of members in the Methanomicrobiales order including the Methanobrevibacter spp., and members of the Methanosarcinaceae. The presence of Methanobrevibacter spp. in dairy manure methanogenic communities is in agreement with their dominance in bovine rumen (Whitford et al., 2001). However, one should remind that the LH-mcrA method has to be coupled to clone library analysis from the same environmental samples for an accurate phylogenetic identification of the peaks. The phylogenetic resolution of the LH-mcrA method was studied by combining clone library analysis to LH-mcrA data. The Methanoculleus-related phylotypes were not only found in the 483-bp amplicon: some of them were comprised in the 485-bp amplicon.