Abstract
Desulfonema ishimotonii strain Tokyo 01T is a filamentous sulfate-reducing bacterium isolated from a marine sediment. In this study, the genome of this strain was sequenced and analyzed with a focus on gene transfer from phylogenetically distant organisms. While the strain belongs to the class Deltaproteobacteria, hundreds of proteins encoded in the genome showed the highest sequence similarities to those of organisms outside of the class Deltaproteobacteria, suggesting that more than 20% of the genome is putatively of foreign origins. Many of these proteins had the highest sequence identities with proteins encoded in the genomes of filamentous bacteria, including giant sulfur oxidizers of the orders Thiotrichales, cyanobacteria of various genera, and uncultured bacteria of the candidate phylum KSB3. As mobile genetic elements transferred from phylogenetically distant organisms, putative inteins were identified in the GyrB and DnaE proteins encoded in the genome of strain Tokyo 01T. Genes involved in DNA recombination and repair were enriched in comparison to the closest relatives in the same family. Some of these genes were also related to those of organisms outside of the class Deltaproteobacteria, suggesting that they were acquired by horizontal gene transfer from diverse bacteria. The genomic data suggested significant genetic transfer among filamentous gliding bacteria in phylogenetically dispersed lineages including filamentous sulfate reducers. This study provides insights into the genomic evolution of filamentous bacteria belonging to diverse lineages, characterized by various physiological functions and different ecological roles.
Highlights
The genus Desulfonema belongs to the family Desulfobacteraceae in the class Deltaproteobacteria (Kuever, 2014)
Open-reading frames likely to encode proteins were identified as coding sequences (CDSs) by MetaGene Annotator (Noguchi et al, 2008)
We showed that the genome of strain Tokyo 01T appears to have many protein-coding genes with wide phylogenetic affiliations, implying extensive genetic transfer from diverse organisms
Summary
The genus Desulfonema belongs to the family Desulfobacteraceae in the class Deltaproteobacteria (Kuever, 2014). This genus encompasses mesophilic filamentous sulfate-reducing bacteria which have gliding motility (Kuever et al, 2015). Desulfonema organisms were abundant in the oxic layer of cyanobacterial mats (Teske et al, 1998; Minz et al, 1999). These findings of physical association imply that Desulfonema species have close relationships with filamentous sulfur oxidizers and cyanobacteria, which may drive cycles of sulfur and carbon
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
