Title: Large Circular Plasmids from Groundwater Plasmidomes Span Multiple Incompatibility Groups and Are Enriched in Multimetal Resistance Genes

Abstract

Naturally occurring plasmids constitute a major category of mobile genetic elements responsible for harboring and transferring genes important in survival and fitness. A targeted evaluation of plasmidomes can reveal unique adaptations required by microbial communities. We developed a model system to optimize plasmid DNA isolation procedures targeted to groundwater samples which are typically characterized by low cell density (and likely variations in the plasmid size and copy numbers). The optimized method resulted in successful identification of several hundred circular plasmids, including some large plasmids (11 plasmids more than 50 kb in size, with the largest being 1.7 Mb in size). Several interesting observations were made from the analysis of plasmid DNA isolated in this study. The plasmid pool (plasmidome) was more conserved than the corresponding microbiome distribution (16S rRNA based). The circular plasmids were diverse as represented by the presence of seven plasmid incompatibility groups. The genes carried on these groundwater plasmids were highly enriched in metal resistance. Results from this study confirmed that traits such as metal, antibiotic, and phage resistance along with toxin-antitoxin systems are encoded on abundant circular plasmids, all of which could confer novel and advantageous traits to their hosts. This study confirms the ecological rolemore » of the plasmidome in maintaining the latent capacity of a microbiome, enabling rapid adaptation to environmental stresses. IMPORTANCEPlasmidomes have been typically studied in environments abundant in bacteria, and this is the first study to explore plasmids from an environment characterized by low cell density. We specifically target groundwater, a significant source of water for human/agriculture use. We used samples from a well-studied site and identified hundreds of circular plasmids, including one of the largest sizes reported in plasmidome studies. The striking similarity of the plasmid-borne ORFs in terms of taxonomical and functional classifications across several samples suggests a conserved plasmid pool, in contrast to the observed variability in the 16S rRNA-based microbiome distribution. Additionally, the stress response to environmental factors has stronger conservation via plasmid-borne genes as marked by abundance of metal resistance genes. Last, identification of novel and diverse plasmids enriches the existing plasmid database(s) and serves as a paradigm to increase the repertoire of biological parts that are available for modifying novel environmental strains.« less

Authors:

Kothari, Ankita ;

• Search DOE PAGES for author "Kothari, Ankita"
• Search DOE PAGES for ORCID "0000-0002-6241-5821"

Wu, Yu-Wei; Chandonia, John-Marc ;

• Search DOE PAGES for author "Chandonia, John-Marc"
• Search DOE PAGES for ORCID "0000-0002-5153-9079"

Charrier, Marimikel ;

• Search DOE PAGES for author "Charrier, Marimikel"
• Search DOE PAGES for ORCID "0000-0003-4264-5985"

Rajeev, Lara; Rocha, Andrea M.; Joyner, Dominique C.; Hazen, Terry C. ;

• Search DOE PAGES for author "Hazen, Terry C."
• Search DOE PAGES for ORCID "0000-0002-2536-9993"

Singer, Steven W.; Mukhopadhyay, Aindrila ;

• Search DOE PAGES for author "Mukhopadhyay, Aindrila"
• Search DOE PAGES for ORCID "0000-0002-6513-7425"

Winans, ed., Stephen Carlyle

Publication Date:

Tue Feb 26 00:00:00 EST 2019

Research Org.:

Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:

1496501

Alternate Identifier(s):

OSTI ID: 1528692; OSTI ID: 1545317

Grant/Contract Number:  

AC02-05CH11231; AC05-00OR22725

Resource Type:

Published Article

Journal Name:

mBio (Online)

Additional Journal Information:

Journal Name: mBio (Online) Journal Volume: 10 Journal Issue: 1; Journal ID: ISSN 2150-7511

Publisher:

American Society for Microbiology

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES