Evidence map›Paper›PMID 27993152›Full record

ArticleMicrobial cell factories2016

Copy number variability of expression plasmids determined by cell sorting and Droplet Digital PCR.

Michael Jahn, Carsten Vorpahl, Thomas Hübschmann, Hauke Harms, Susann Müller

Open access · goldAbstract read
In one paragraph

Article in Microbial cell factories, 2016. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 98 papers.

0numbers the graph read from it
0cells of the map it votes in
98citing papers in PubMed
4.2field-weighted citation impact, top 5% of its field
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.

3 · Its place in the literature

Who cites it

98 citing papers in PubMed, 202 citations in OpenAlex.

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  8. A modular single- and dual-gene expression toolkit for Kluyveromyces marxianus.World journal of microbiology & biotechnology · 2026
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  17. Universal rules govern plasmid copy number.Nature communications · 2025
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38 more citing papers are in PubMed but not listed here.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

5 authors at 1 institution in 2 countries.

Michael JahnHelmholtz-Centre for Environmental Research-UFZ, Permoserstraße 15, 04318, Leipzig, Germany.ORCID http://orcid.org/0000-0002-3913-153X
Carsten VorpahlHelmholtz-Centre for Environmental Research-UFZ, Permoserstraße 15, 04318, Leipzig, Germany.
Thomas HübschmannHelmholtz-Centre for Environmental Research-UFZ, Permoserstraße 15, 04318, Leipzig, Germany.
Hauke HarmsHelmholtz-Centre for Environmental Research-UFZ, Permoserstraße 15, 04318, Leipzig, Germany.
Susann MüllerHelmholtz-Centre for Environmental Research-UFZ, Permoserstraße 15, 04318, Leipzig, Germany. susann.mueller@ufz.de.
Helmholtz Centre for Environmental Research · DE

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundPlasmids are widely used for molecular cloning or production of proteins in laboratory and industrial settings. Constant modification has brought forth countless plasmid vectors whose characteristics in terms of average plasmid copy number (PCN) and stability are rarely known. The crucial factor determining the PCN is the replication system; most replication systems in use today belong to a small number of different classes and are available through repositories like the Standard European Vector Architecture (SEVA).

resultsIn this study, the PCN was determined in a set of seven SEVA-based expression plasmids only differing in the replication system. The average PCN for all constructs was determined by Droplet Digital PCR and ranged between 2 and 40 per chromosome in the host organism Escherichia coli. Furthermore, a plasmid-encoded EGFP reporter protein served as a means to assess variability in reporter gene expression on the single cell level. Only cells with one type of plasmid (RSF1010 replication system) showed a high degree of heterogeneity with a clear bimodal distribution of EGFP intensity while the others showed a normal distribution. The heterogeneous RSF1010-carrying cell population and one normally distributed population (ColE1 replication system) were further analyzed by sorting cells of sub-populations selected according to EGFP intensity. For both plasmids, low and highly fluorescent sub-populations showed a remarkable difference in PCN, ranging from 9.2 to 123.4 for ColE1 and from 0.5 to 11.8 for RSF1010, respectively.

conclusionsThe average PCN determined here for a set of standardized plasmids was generally at the lower end of previously reported ranges and not related to the degree of heterogeneity. Further characterization of a heterogeneous and a homogeneous population demonstrated considerable differences in the PCN of sub-populations. We therefore present direct molecular evidence that the average PCN does not represent the true number of plasmid molecules in individual cells.

Indexed as

DNA Copy Number VariationsEscherichia coliFlow CytometryPlasmidsPolymerase Chain ReactionCell sortingEGFPEscherichia coliOrigin of replicationPlasmid copy numberPopulation heterogeneityReplication systemSEVASub-populationVariability

Identifiers

PMID27993152
PMCPMC5168713
OpenAlexW2563908666

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LicenceCC BY
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Registered trials

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.