Eberhart LJ, Knutson CM, Barney BM. A methodology for markerless genetic modifications in Azotobacter vinelandii.
J Appl Microbiol 2017;
120:1595-604. [PMID:
26854474 DOI:
10.1111/jam.13091]
[Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 01/29/2016] [Accepted: 01/30/2016] [Indexed: 01/03/2023]
Abstract
AIMS
Efficient manipulation of multiple regions within a genome can be improved by counter-selection approaches. In this work, we sought to develop a method to manipulate Azotobacter vinelandii using a counter-selection approach based on the presence of the pyrF gene.
METHODS AND RESULTS
A background uracil auxotroph of A. vinelandii was first constructed by deleting the pyrF gene coding orotidine-5'-phosphate decarboxylase. The pyrF gene and promoter were also incorporated together with an antibiotic marker to create a selection and counter-selection cassette to shuttle into various plasmids. The constructed cassette could then be removed using a plasmid lacking the pyrF gene via counter-selection resulting from the production of 5-fluorouracil. The process could be repeated multiple times using the same procedure for selection and counter-selection. Following completion, the pyrF gene may be reintroduced to the genome in its original location, leaving a completed strain devoid of any antibiotic markers.
CONCLUSIONS
Utilization of the pyrF gene for counter-selection is a powerful tool that can be used effectively to make multiple gene deletions in A. vinelandii.
SIGNIFICANCE AND IMPACT OF THE STUDY
This study demonstrates the successful application of a counter-selection approach to yield markerless genetic modifications to A. vinelandii, which should be of interest for a range of applications in this important model bacterium.
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