Biology subjects

Besse, A.

Publications and source records attributed to Besse, A..

3 recordsLinked to original sources

bioRxiv2022

Emergence of Small Colony Variants (SCVs) is an adaptive strategy used by Pseudomonas aeruginosa to palliate O2 limitations

The ability to generate a subpopulation of Small Colony Variants (SCVs) is a conserved feature of Pseudomonas aeruginosa and could represent a key adaptive strategy to colonize and persist in multiple niches. However, very little is known about the role of the SCV phenotype, the conditions that promote its emergence and its possible involvement in an adaptive strategy. In the present work, we investigated the in vitro selective conditions promoting the emergence of SCVs from the prototypical strain PA14, which readily forms SCVs in non-agitated standing cultures. We found that O2 limitations, which cause a redox imbalance, is the main factor selecting for the SCV phenotype, which promotes survival of the population via formation of a biofilm at the air-liquid interface to access the electron acceptor. When this selective pressure is relieved by aeration or supplementation of an alternative electron acceptor, SCVs are barely detectable. We also observed that SCV emergence contributes to redox rebalancing, suggesting that it is involved in an adaptive strategy. We conclude that selection for the SCV phenotype is an adaptive solution adopted by P. aeruginosa to access poorly available O2. IMPORTANCEThe bacterium P. aeruginosa is an opportunistic pathogen that thrives in many environments. It poses a significant health concern, notably because it is a causative agent of nosocomial infections and the most prevalent pathogen found in the lungs of people with cystic fibrosis. In infected hosts, its persistence is often related to the emergence of an alternative phenotype known as Small Colony Variant (SCV). Identification of conditions selecting for the SCV phenotype contributes to knowledge regarding adaptive mechanisms exploited by P. aeruginosa to survive in multiple niches and persist during infections. Hindering this adaptation strategy could help control P. aeruginosa persistent infections.

microbiology↗

bioRxiv2022

Pseudomonas aeruginosa strains from both clinical and environmental origins readily adopt a stable small colony variant (SCV) phenotype resulting from single mutations in c-di-GMP pathways

A subpopulation of Small Colony Variants (SCVs) is a frequently observed feature of Pseudomonas aeruginosa isolated from colonized cystic fibrosis lungs. Since most SCVs have until now been isolated from clinical samples, it remains unclear how widespread is the ability of P. aeruginosa to develop this phenotype and the genetic mechanism(s) behind SCVs emergence according to the origin of the isolate. In the present work, we investigated the ability of 22 P. aeruginosa isolates from various environmental origins to, under laboratory culture conditions, spontaneously adopt a SCV-like smaller alternative morphotype distinguishable from the ancestral parent strain. We found that all the P. aeruginosa strains tested could adopt a SCV phenotype, regardless of their origin. Whole genome sequencing of SCVs obtained from clinical and environmental sources revealed single mutations exclusively in two distinct c-di-GMP signaling pathways, Wsp and YfiBNR. We conclude that the ability to switch to a SCV phenotype is a conserved feature of P. aeruginosa and results from the acquisition of a stable genetic mutation, regardless of the origin of the strain. IMPORTANCEP. aeruginosa is an opportunistic pathogen that thrives in many environments. It poses a significant health concern, notably because this bacterium is the most prevalent pathogen found in the lungs of people with cystic fibrosis. In infected hosts, its persistence is considered related to the emergence of an alternative small colony variant (SCV) phenotype. By reporting the distribution of P. aeruginosa SCVs in various non-clinical environments and the involvement of c-di-GMP in SCV emergence from both clinical and environmental strains, this work contributes to understanding a conserved adaptation mechanism used by P. aeruginosa to adapt readily in all environments. Hindering this adaptation strategy could help control P. aeruginosa persistent infection.

microbiology↗

bioRxiv2021

The ability of Pseudomonas aeruginosa to adopt a Small Colony Variant (SCV) phenotype is conserved, and not restricted to clinical isolates

A subpopulation of Small Colony Variants (SCVs) is a frequently observed feature of Pseudomonas aeruginosa isolated from cystic fibrosis (CF) lungs biofilms. SCVs have almost exclusively been reported from infected hosts, essentially CF individuals or, by extension, from laboratory cultivation of strains originated from infected hosts. We previously reported the identification of P. aeruginosa SCVs emerging from a non-clinical strain and displaying features shared with clinical SCVs. In the present work, we investigated the ability of 22 P. aeruginosa isolates from various environmental origins to, under laboratory culture conditions, spontaneously adopt a SCV-like smaller alternative morphotype distinguishable from the ancestral parent strain. Unexpectedly, we found that all the P. aeruginosa strains tested have the ability to adopt a SCV morphotype, regardless of their origin. Based on the phenotypes already described for SCVs, the SCV-like morphotypes obtained were clustered in two groups displaying various phenotypic profiles, including one characteristic of already described SCVs. We conclude that the ability to switch to a SCV phenotype is a conserved feature in Pseudomonas aeruginosa. IMPORTANCEP. aeruginosa is an opportunistic pathogen that thrives in many environments. It is significant public health concern, notably because it is the most prevalent pathogen found in the lungs of people with cystic fibrosis (CF). In infected hosts, its persistence is believed to be related to the emergence of an alternative small colony variant (SCV) phenotype. By reporting the distribution of P. aeruginosa SCVs in various non-clinical environments, this work contributes to understanding a conserved adaptation mechanism used by P. aeruginosa to rapidly adapt in all environments. Counteraction of this strategy could prevent P. aeruginosa persistent infection in the future.

microbiology↗