Protein-Coding Genes as Alternative Markers in Microbial Diversity Studies
The small ribosomal unit RNA (SSU rRNA or 16S rRNA) has been widely used in microbial systematic and diversity studies. The appeal of using 16S rRNA gene as a marker gene is numerous. First of all, it is distributed in every single cellular organism. Secondly, because regions of 16S rRNA sequence are highly conserved, 16S rRNA gene can be PCR amplified from a wide diversity of taxa using “universal” primers and sequenced, bypassing the need to isolate and culture the organisms in question. Consequently, millions of 16S rRNA reference sequences are available for microbial classification and identification (Cole 2009).
Although 16S rRNA has been the “gold standard” in microbial diversity studies, it has several shortcomings. First, because 16S rRNA only makes up a tiny fraction of a genome (~0.1 %), its application as a marker gene in classifying metagenomic sequences is seriously limited. Secondly, the widely...
KeywordsHide Markov Model Marker Gene Lateral Gene Transfer Metagenomic Sequence Evolutionary Rate Variation
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