Phylogenetic Evidence for Lateral Gene Transfer in the Intestine of Marine Iguanas

Appalachian Laboratory, University of Maryland Center for Environmental Science, Frostburg, Maryland, USA.
PLoS ONE (Impact Factor: 3.53). 05/2010; 5(5):e10785. DOI: 10.1371/journal.pone.0010785
Source: PubMed

ABSTRACT Lateral gene transfer (LGT) appears to promote genotypic and phenotypic variation in microbial communities in a range of environments, including the mammalian intestine. However, the extent and mechanisms of LGT in intestinal microbial communities of non-mammalian hosts remains poorly understood.
We sequenced two fosmid inserts obtained from a genomic DNA library derived from an agar-degrading enrichment culture of marine iguana fecal material. The inserts harbored 16S rRNA genes that place the organism from which they originated within Clostridium cluster IV, a well documented group that habitats the mammalian intestinal tract. However, sequence analysis indicates that 52% of the protein-coding genes on the fosmids have top BLASTX hits to bacterial species that are not members of Clostridium cluster IV, and phylogenetic analysis suggests that at least 10 of 44 coding genes on the fosmids may have been transferred from Clostridium cluster XIVa to cluster IV. The fosmids encoded four transposase-encoding genes and an integrase-encoding gene, suggesting their involvement in LGT. In addition, several coding genes likely involved in sugar transport were probably acquired through LGT.
Our phylogenetic evidence suggests that LGT may be common among phylogenetically distinct members of the phylum Firmicutes inhabiting the intestinal tract of marine iguanas.

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Available from: David Nelson, Jul 21, 2015
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    • "A previous attempt to isolate novel bacteria from Galápagos marine iguana feces resulted in a range of Clostridia isolated from media containing different carbohydrate sources, and these isolates await full identification and characterization (Mackie, unpublished data). In a separate enrichment culture that actively degraded agar by rapid liquefaction, repeated attempts to isolate pure cultures of the agar-degraders failed, suggesting novel metabolic and functional pathways, operating synergistically , that require further elucidation before subsequent isolation attempts (Nelson et al., 2010). "
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