The Nocardia cyriacigeorgica GUH-2 genome shows ongoing adaptation of an environmental Actinobacteria to a pathogen’s lifestyle

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.

Molecular identification of clinical Nocardia isolates from India

“…Intraspecies variation in susceptibility to imipenem has also been reported in N. cyriacigeorgica (Schlaberg et al, 2014). Recently, genomic sequencing of N. cyriacigeorgica (GUH-2 strain) revealed virulence determinants such as the production of superoxide dismutase and peptide synthesis probably for siderophore/toxin production (Zoropogui et al, 2013).…”

Pathogenic Nocardia: A diverse genus of emerging pathogens or just poorly recognized?

“…It may be argued that modern molecular biology tools have improved diagnosis of this elusive pathogen and enabled finer species level identification, giving increased recognition to this well-established, rather than emerging, genus as an agent of infection. Conversely, information obtained from whole genome sequencing of at least one N. cyriacigeorgica genome suggests that this organism is on the path of an ongoing adaptation from an environmental bacterium to an emerging pathogen [52]. In either case, it is clear that accurate diagnosis and timely treatment of nocardial infections are crucial because undiagnosed and latent infections have the ability to spread from primary sites to more sensitive regions in the body that can be fatal.…”

Insights into the Microbial Degradation of Rubber and Gutta-Percha by Analysis of the Complete Genome of Nocardia nova SH22a

“…A comparison of the SH22a genome with the other three fully sequenced genomes of the genus Nocardia (N. farcinica IFM 10152 [31], Nocardia cyriacigeorgica GUH-2 [32], and Nocardia brasiliensis HUJEG-1 [33]) was carried out. These analyses revealed that in comparison to the predicted proteomes of the other Nocardia strains, many protein families of SH22a which might be involved in the degradation of xenobiotics, other hardly degradable compounds, and polymers are represented at higher percentages.…”