Ultra-deep pyrosequencing of pmoA amplicons confirms the prevalence of Methylomonas and Methylocystis in Sphagnum mosses from a Dutch peat bog

Sphagnum peatlands are important ecosystems in the methane cycle. Methanotrophs in these ecosystems have been shown to reduce methane emissions and provide additional carbon to Sphagnum mosses. However, little is known about the diversity and identity of the methanotrophs present in and on Sphagnum mosses in these peatlands. In this study, we applied a pmoA microarray and high-throughput 454 pyrosequencing to pmoA PCR products obtained from total DNA from Sphagnum mosses from a Dutch peat bog to investigate the presence of methanotrophs and to compare the two different methods. Both techniques showed comparable results and revealed an abundance of Methylomonas and Methylocystis species in the Sphagnum mosses. The advantage of the microarray analysis is that it is fast and cost-effective, especially when many samples have to be screened. Pyrosequencing is superior in providing pmoA sequences of many unknown or uncultivated methanotrophs present in the Sphagnum mosses and, thus, provided much more detailed and quantitative insight into the microbial diversity.