A total of 3,378 genes (77.42%) were assigned a putative function. The remaining genes were annotated as hypothetical proteins. The properties and statistics of the genome are summarized in Table 3. The distribution of genes into COGs functional categories is presented in Table 4. Table 3 Nucleotide content and gene count levels of the genome Figure 2 Graphical sellectchem circular map of the S. enterica subsp. houtenae strain RKS 3027 genome. From the outside to the center: genes on forward strand (color by COG categories), genes on reverse strand (color by COG categories), GC content, GC skew. The map was generated … Table 4 Number of genes associated with the 25 general COG functional categories Acknowledgments This work was supported by grants of the National Natural Science Foundation of China (NSFC30970119, 81030029, 81271786, NSFC-NIH 81161120416) to SLL.

Methanobrevibacter sp. AbM4 was isolated and purified from the abomasum of a sheep maintained as part of a study into effects of the nematode Ostertagia circumcincta on the abomasal environment [5] (Keith Joblin, personal communication). AbM4 is a member of the methanogenic archaea. It is a strict anaerobe and its hydrogenotrophic metabolism is characterized by its ability to produce methane from hydrogen, carbon dioxide and formate. A phylogenetic analysis of the AbM4 small subunit ribosomal RNA (ssrRNA) gene sequence places it closest to Methanobrevibacter wolinii and the sequence is approximately 95% similar to the M. wolinii type strain SH [Figure 1].

Although an ovine abomasal isolate, ssrRNA gene sequences identical, or with >97% similarity to that of AbM4 have also been reported among methanogen sequences derived from rumen contents of both sheep and cattle [8-10]. Searches of the Genbank and the Ribosomal Database Project databases also show sequences >97% similar to AbM4 occur in yak (Genbank accession “type”:”entrez-nucleotide”,”attrs”:”text”:”JF807172″,”term_id”:”334361753″,”term_text”:”JF807172″JF807172), in sheep in Venezuela [11] Batimastat and Western Australia [12], in alpacas [13] and Jersey dairy cows farmed in the USA [14], as well as in the feces of manatee in Florida, USA (Genbank accession “type”:”entrez-nucleotide”,”attrs”:”text”:”HQ599703″,”term_id”:”315111442″,”term_text”:”HQ599703″HQ599703, “type”:”entrez-nucleotide”,”attrs”:”text”:”HQ599742″,”term_id”:”315111481″,”term_text”:”HQ599742″HQ599742). The cellular morphology of AbM4 was determined by electron microscopy (Fig. 2). For this, AbM4 cells were grown on RM02 medium [2] and were negatively stained with 1% phosphotungstic acid, mounted on Formvar-coated copper grids. Grids were examined using a Philips model 201C electron microscope. AbM4 is a short rod and is not motile [Figure 2].