Aims: To characterize the composition of microbial populations in a distribution system simulator (DSS) by direct sequence analysis of 16S rDNA clone libraries. Methods and Results: Bacterial populations were examined in chlorinated distribution water and chloraminated DSS feed and discharge water. Bacterial strains isolated from DSS discharge water on R2A medium were identified using 16S rDNA sequence analysis. The majority of the bacteria identified were a-proteobacteria, ranging from approx. 34% in the DSS discharge water to 94% of the DSS isolates. Species richness estimators Chao1 and ACE (abundance-based coverage estimators) indicated that the chlorinated distribution water sample was representative of the total population diversity, while the chloraminated DSS feed water sample was dominated by Hyphomicrobium sp. sequences. The DSS discharge water contained the greatest diversity of a-, b-, cproteobacteria, with 36% of the sequences being operational taxonomic units (OTUs, sequences with >97AE0% homology). Conclusions: This work demonstrated the dominance of a-proteobacteria in distribution system water under two different disinfectant residuals. The shift from chlorine to monochloramine residual may have played a role in bacterial population dynamics. Significance and Impact of the Study: Accurate identification of bacteria present in treated drinking water is needed in order to better determine the risk of regrowth of potentially pathogenic organisms within distribution systems.
The significant association between vaccination and isolate pertactin production suggests that the likelihood of having reported disease caused by PRN(-) compared with PRN(+) strains is greater in vaccinated persons. Additional studies are needed to assess whether vaccine effectiveness is diminished against PRN(-) strains.
Abstract1 The several forms of ecological spatial connectivity -population, genetic, community, ecosystem -are among the most important ecological processes in determining the distribution, persistence and productivity of coastal marine populations and ecosystems.2 Ecological marine protected areas (MPAs) focus on restoring or maintaining marine populations, communities, or ecosystems. All ecological MPAs -no matter their specific focus or objectives -depend for their success on incorporating ecological spatial connectivity into their design, use (i.e. application), and management.3 Though important, a synthesis of the implications of ecological spatial connectivity for the design, use, and management of MPAs, especially in the face of a changing global climate, does not exist. We synthesize this information and distill it into practical principles for design, use, and management of MPAs and networks of MPAs.4 High population connectivity among distant coastal ecosystems underscores the critical value of MPA networks for MPAs and the populations and ecosystems between them.5 High ecosystem connectivity among coastal ecosystems underscores the importance of protecting multiple connected ecosystems within an MPA, maximizing ecosystem connectivity across MPAs, and managing ecosystems outside MPAs so as to minimize influxes of detrimental organisms and materials into MPAs.6 Connectivity-informed MPAs and MPA networks -designed and managed to foster the ecological spatial connectivity processes important to local populations, species, communities, and ecosystems -can best address ecological changes induced by climate change. Also, the protections afforded by MPAs from direct, local human impacts may ameliorate climate change impacts in coastal ecosystems inside MPAs and, indirectly, in ecosystems outside MPAs.
Despite high pertussis vaccine coverage, reported cases of whooping cough (pertussis) have increased over the last decade in the United States and other developed countries. Although Bordetella pertussis is well known for its limited gene sequence variation, recent advances in long-read sequencing technology have begun to reveal genomic structural heterogeneity among otherwise indistinguishable isolates, even within geographically or temporally defined epidemics. We have compared rearrangements among complete genome assemblies from 257 B. pertussis isolates to examine the potential evolution of the chromosomal structure in a pathogen with minimal gene nucleotide sequence diversity. Discrete changes in gene order were identified that differentiated genomes from vaccine reference strains and clinical isolates of various genotypes, frequently along phylogenetic boundaries defined by single nucleotide polymorphisms. The observed rearrangements were primarily large inversions centered on the replication origin or terminus and flanked by IS481, a mobile genetic element with Ͼ240 copies per genome and previously suspected to mediate rearrangements and deletions by homologous recombination. These data illustrate that structural genome evolution in B. pertussis is not limited to reduction but also includes rearrangement. Therefore, although genomes of clinical isolates are structurally diverse, specific changes in gene order are conserved, perhaps due to positive selection, providing novel information for investigating disease resurgence and molecular epidemiology.IMPORTANCE Whooping cough, primarily caused by Bordetella pertussis, has resurged in the United States even though the coverage with pertussis-containing vaccines remains high. The rise in reported cases has included increased disease rates among all vaccinated age groups, provoking questions about the pathogen's evolution. The chromosome of B. pertussis includes a large number of repetitive mobile genetic elements that obstruct genome analysis. However, these mobile elements facilitate large rearrangements that alter the order and orientation of essential protein-encoding genes, which otherwise exhibit little nucleotide sequence diversity. By comparing the complete genome assemblies from 257 isolates, we show that specific rearrangements have been conserved throughout recent evolutionary history, perhaps by eliciting changes in gene expression, which may also provide useful information for molecular epidemiology.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.