A phylogenetic census of global diversity of gut anaerobic fungi and a new taxonomic framework

The Vienna RNA secondary structure server provides a web interface to the most frequently used functions of the Vienna RNA software package for the analysis of RNA secondary structures. It currently offers prediction of secondary structure from a single sequence, prediction of the consensus secondary structure for a set of aligned sequences and the design of sequences that will fold into a predefined structure. All three services can be accessed via the Vienna RNA web server at http://rna.tbi.univie.ac.at/.

The objective of this study was to generate a phylogenetic diversity census of bacteria identified in the intestinal tract of chickens and turkeys using a naïve analysis of all the curated 16S rRNA gene sequences archived in public databases. High-quality sequences of chicken and turkey gastrointestinal origin (3,184 and 1,345, respectively) were collected from the GenBank, Ribosomal Database Project, and Silva comprehensive ribosomal RNA database. Through phylogenetic and statistical analysis, 915 and 464 species-equivalent operational taxonomic units (defined at 0.03 phylogenetic distance) were found in the chicken and the turkey sequence collections, respectively. Of the 13 bacterial phyla identified in both bird species, Firmicutes, Bacteroidetes, and Proteobacteria were the largest phyla, accounting for >90% of all the sequences. The chicken sequences represent 117 established bacterial genera, and the turkey sequences represent 69 genera. The most predominant genera found in both the chicken and the turkey sequence data sets were Clostridium, Ruminococcus, Lactobacillus, and Bacteroides, but with different distribution between the 2 bird species. The estimated coverage of bacterial diversity of chicken and turkey reached 89 and 68% at species-equivalent and 93 and 73% at genus-equivalent levels, respectively. Less than 7,000 bacterial sequences from each bird species from various locations would be needed to reach 99% coverage for either bird species. Based on annotation of the sequence records, cecum was the most sampled gut segment. Chickens and turkeys were shown to have distinct intestinal microbiomes, sharing only 16% similarity at the species-equivalent level. Besides identifying gaps in knowledge on bacterial diversity in poultry gastrointestinal tract, the bacterial census generated in this study may serve as a framework for future studies and development of analytic tools.

In this study, the collective microbial diversity in the rumen was examined by performing a meta-analysis of all the curated 16S rRNA gene (rrn) sequences deposited in the RDP database. As of November 2010, 13,478 bacterial and 3516 archaeal rrn sequences were found. The bacterial sequences were assigned to 5271 operation taxonomic units (OTUs) at species level (0.03 phylogenetic distance) representing 19 existing phyla, of which the Firmicutes (2958 OTUs), Bacteroidetes (1610 OTUs) and Proteobacteria (226 OTUs) were the most predominant. These bacterial sequences were grouped into more than 3500 OTUs at genus level (0.05 distance), but only 180 existing genera were represented. Nearly all the archaeal sequences were assigned to 943 species-level OTUs in phylum Euryarchaeota. Although clustered into 670 genus-level OTUs, only 12 existing archaeal genera were represented. Based on rarefaction analysis, the current percent coverage at species level reached 71% for bacteria and 65% for archaea. At least 78,218 bacterial and 24,480 archaeal sequences would be needed to reach 99.9% coverage. The results of this study may serve as a framework to assess the significance of individual populations to rumen functions and to guide future studies to identify the alpha and global diversity of ruminal microbiomes. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.