The spyder output, which consists

of a text file summarizing the location of indels and substitutions, was used to identify locations where degeneracies could be introduced to compensate for common mismatches. A second analysis using RDP Probe Match was used to evaluate the new primer and verify that it did not compromise specificity (Table 4). oligocalc confirmed primer quality, including a suitable GC content, and the absence of self-complementarity, hairpins, and 3′- primer–primer complementarity (data not shown). The most substantial improvements http://www.selleckchem.com/products/pf-562271.html were for the primers targeting Alphaproteobacteria (Alf28f), Gammaproteobacteria (Gamma395f), Bacteriodetes (CFB555f), Firmicutes (Firm350f), and Archaea (A571F) resulting in 22%, 42%, 15%, 18%, and 26% increases in coverage, respectively, while nonspecific mismatches remained low (0.03–2.56%) (Table 4). Analysis of primers designed using arb and primrose (i.e. those designed by Muhling et al., 2008) by spyder indicated that these primers could be improved without sacrificing specificity by adding targeted degeneracies (Table 4). This may be because current databases are more comprehensive and/or that arb does not include a feature for including degeneracies in primer design (Muhling et al., 2008). spyder also identified improvements (5.9% increase) of the commonly

used eubacterial primer F27, which is the forward primer used along with R1492 for the Human Microbiome

Project Sanger sequencing libraries CX-5461 price (Turnbaugh et al., 2007). The F27 primer was also the forward primer of choice in the recent survey of the microbiota of the oral cavity of healthy adults in which over 10 000 full-length 16S rRNA gene sequences were analyzed (Bik et al., 2010). Methocarbamol In the majority of cases, spyder determined that only the forward or the reverse primer of a standard set could be improved. The lack of nonspecific hits associated with the improved primer indicates that it may be beneficial to use a comprehensive universal or alternate primer to complete the pair in the event that the current primer pair possesses differential coverage. Adding degeneracies is a common method for improving primers; however, it is possible that too many degenerate sites will diminish the primers target specificity. As such, other methods to increase mismatch tolerance should also be considered such as using long primers (25+ bases long), increasing dNTP concentrations, MgCl2, and annealing time, as well as using annealing temperatures below the Tm of the primers (Kwok et al., 1994). PCR cycle number should also be minimized along with the pooling of multiple PCR products to reduce the high variation that is inherent in the early stages of multitemplate PCR (Brooks et al., 2007).