Two Pseudomonas aeruginosa clonal groups belonging to the PA14 clade are indigenous to the Churince system in Cuatro Ciénegas Coahuila, México

Abstract

Summary Pseudomonas aeruginosa is a widely distributed environmental bacterium but is also an opportunistic pathogen that represents an important health hazard due to its high intrinsic antibiotic resistance and its production of virulence factors. The genetic structure of P. aeruginosa populations using whole genome sequences shows the existence of three clades, one of which (PA7 clade) has a higher genetic diversity. These three clades include clinical and environmental isolates that are very diverse in terms of geographical origins and isolation date. Here, we report the characterization of two distinct clonal P. aeruginosa groups that form a part of the PA14 clade (clade 2) sampled from the Churince system in Cuatro Ciénegas Basin (CCB). One of the clonal groups that we report here was isolated in 2011 (group 2A) and was displaced by the other clonal group (2B) in 2015. Both Churince groups are unable to produce pyoverdine but can produce other virulence‐associated traits. The existence of these unique P. aeruginosa clonal groups in the Churince system is of ecological and evolutionary significance since the microbiota of this site is generally very distinct from other lineages, and this is the first time that a population of P. aeruginosa has been found in CCB.

Fast eco-evolutionary changes in bacterial genomes after anthropogenic perturbation

“…However, in that case, the outcome could be easier to predict, given the possible black queen dynamics [82] in B. coahuilensis, which was a specialized lineage with a particularly small genome, lacking several metabolic pathways, therefore, an organism highly dependent on several metabolites from other community members [30,81,83]. What was observed in our study is more intriguing, since P. otitidis is a planktonic generalist that was observed consistently over the years at Churince [43–45, 33, 35, 36] and even experimented a dramatic population increase just before apparently going locally extinct.…”

“…Laguna Intermedia from the Churince system in Cuatro Ciénegas, Coahuila, Mexico (26.848572 N 102.141783 W) suffered four recent desiccation events: October 2011, November 2012, October 2015 and October 2016 before completely drying up in 2017 [24, 36]. Churince was a long-term study site, and water physico-chemical conditions were recorded periodically since 2002 with the multiparameter water quality sonde Hydrolab MS5, until water disappeared from the two main lagoons in the system.…”

“…An in situ nutrient enrichment experiment was performed in Churince using different proportions of N:P, showing that lower N:P ratio favored the proliferation of generalist bacteria and algae at the expense of the typically rare endemic lineages [32–34]. This was the case of pseudomonads, which appeared to benefit from the environmental disturbance [35, 36].…”

“…Biology and ecology of pseudomonads from Churince has been described in different studies [35, 43–45], and more recently two new strains of the P. aeruginosa PA14 clade native to Laguna Intermedia were sampled during the first desiccation event in 2011 [36]. P. otitidis from CCB represented a separate native lineage that was present, but was rare, before the perturbations at Laguna Intermedia [44].…”

Tracking the genome of four Pseudomonas aeruginosa isolates that have a defective Las quorum-sensing system, but are still virulent

“…aeruginosa isolates that are defective in the LasR QS-system, but are able to produce PYO and RL and are virulent (), to determine whether they share some genetic traits that could be used as markers, and compared them with the PAO1 and PA14 type strains. Two of the studied strains are environmental, ID4365 isolated from the Indian Ocean [9] and M66 isolated from the Churince water system in 2011 (belongs to clonal group 2A) [11], one strain was isolated from the stomach of a dolphin [9, 13], and the fourth strain, INP43, is a pediatric Cystic Fibrosis isolate [17]. We focus on the genomic analysis of only these four strains because they have been characterized in terms of their defective Las QS system and their virulence (), and because they represent independent isolates that include environmental, veterinary and clinical strains.…”