Abstract
BackgroundNocardia cyriacigeorgica is recognized as one of the most prevalent etiological agents of human nocardiosis. Human exposure to these Actinobacteria stems from direct contact with contaminated environmental matrices. The full genome sequence of N. cyriacigeorgica strain GUH-2 was studied to infer major trends in its evolution, including the acquisition of novel genetic elements that could explain its ability to thrive in multiple habitats.ResultsN. cyriacigeorgica strain GUH-2 genome size is 6.19 Mb-long, 82.7% of its CDS have homologs in at least another actinobacterial genome, and 74.5% of these are found in N. farcinica. Among N. cyriacigeorgica specific CDS, some are likely implicated in niche specialization such as those involved in denitrification and RuBisCO production, and are found in regions of genomic plasticity (RGP). Overall, 22 RGP were identified in this genome, representing 11.4% of its content. Some of these RGP encode a recombinase and IS elements which are indicative of genomic instability. CDS playing part in virulence were identified in this genome such as those involved in mammalian cell entry or encoding a superoxide dismutase. CDS encoding non ribosomal peptide synthetases (NRPS) and polyketide synthases (PKS) were identified, with some being likely involved in the synthesis of siderophores and toxins. COG analyses showed this genome to have an organization similar to environmental Actinobacteria.ConclusionN. cyriacigeorgica GUH-2 genome shows features suggesting a diversification from an ancestral saprophytic state. GUH-2 ability at acquiring foreign DNA was found significant and to have led to functional changes likely beneficial for its environmental cycle and opportunistic colonization of a human host.
Highlights
Nocardia cyriacigeorgica is recognized as one of the most prevalent etiological agents of human nocardiosis
These comparisons highlighted regions of genomic plasticity (RGP) among the N. cyriacigeorgica GUH-2 genome. Selection of these RGP was probably a driving force in the emergence of N. cyriacigeorgica GUH-2. These results revealed highly dynamic genomic evolutionary patterns in N. cyriacigeorgica caused by a significant ability at acquiring foreign DNA
On one hand, primary pathogens are subjected to evolutionary forces driven by the host defense responses which can lead to a specialization for certain hosts and a genome size reduction as observed for B. mallei [62]
Summary
Nocardia cyriacigeorgica is recognized as one of the most prevalent etiological agents of human nocardiosis. N. cyriacigeorgica can be differentiated from other species by 16S rDNA sequence analysis, their ability at growing on acetamide but inability at using proline as carbon and nitrogen sources. N. cyriacigeorgica strains were described as etiological agents of human pneumonia, brain abscesses, and kidney, heart and eye infections [4,7,8,9,10,11,12] It is the most prevalent species involved in human nocardiosis in North America [11,13] and its prevalence in France was estimated at 12% among human nocardial infections declared between 2000 and 2007 [14]. N. cyriacigeorgica strains have been recovered from oil contaminated soils [15,16], and were shown to oxidize a variety of aliphatic compounds [17]
Sign-in/Register to view highlights & summary 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.
