Mobile Elements in a Single-Filament Orange Guaymas Basin Beggiatoa (“Candidatus Maribeggiatoa”) sp. Draft Genome: Evidence for Genetic Exchange with Cyanobacteria
ABSTRACT
The draft genome sequence of a single orange
Beggiatoa
(“
Candidatus
Maribeggiatoa”) filament collected from a microbial mat at a hydrothermal site in Guaymas Basin (Gulf of California, Mexico) shows evidence of extensive genetic exchange with cyanobacteria, in particular for sensory and signal transduction genes. A putative homing endonuclease gene and group I intron within the 23S rRNA gene; several group II catalytic introns; GyrB and DnaE inteins, also encoding homing endonucleases; multiple copies of sequences similar to the
fdxN
excision elements XisH and XisI (required for heterocyst differentiation in some cyanobacteria); and multiple sequences related to an open reading frame (ORF) (00024_0693) of unknown function all have close non-
Beggiatoaceae
matches with cyanobacterial sequences. Sequences similar to the uncharacterized ORF and Xis elements are found in other
Beggiatoaceae
genomes, a variety of cyanobacteria, and a few phylogenetically dispersed pleiomorphic or filamentous bacteria. We speculate that elements shared among filamentous bacterial species may have been exchanged in microbial mats and that some of them may be involved in cell differentiation.