A Molecular Biology Tool Kit for the Phototrophic Firmicute Heliobacterium modesticaldum

Patricia L. Baker, Gregory S. Orf, Zahid Khan, Levi Espinoza, Sabrina Leung, Kimberly Kevershan, Kevin Edward Redding

Research output: Contribution to journalArticle

Abstract

The heliobacteria are members of the bacterial order Clostridiales and form the only group of phototrophs in the phylum Firmicutes Several physiological and metabolic characteristics make them an interesting subject of investigation, including their minimalist photosynthetic system, nitrogen fixation abilities, and ability to reduce toxic metals. While the species Heliobacterium modesticaldum is an excellent candidate as a model system for the family Heliobacteriaceae, since an annotated genome and transcriptomes are available, studies in this organism have been hampered by the lack of genetic tools. We adapted techniques for genetic manipulation of related clostridial species for use with H. modesticaldum Five heliobacterial DNA methyltransferase genes were expressed in an Escherichia coli strain engineered as a conjugative plasmid donor for broad-host-range plasmids. Premethylation of the shuttle vectors before conjugation into H. modesticaldum is absolutely required for production of transconjugant colonies. The introduced shuttle vectors are maintained stably and can be recovered using a modified minipreparation procedure developed to inhibit endogenous DNase activity. Furthermore, we describe the formulation of various growth media, including a defined medium for metabolic studies and isolation of auxotrophic mutants.IMPORTANCE Heliobacteria are anoxygenic phototrophic bacteria with the simplest known photosynthetic apparatus. They are unique in using bacteriochlorophyll g as their main pigment and lacking a peripheral antenna system. Until now, research on this organism has been hampered by the lack of a genetic transformation system. Without such a system, gene knockouts, site-directed mutations, and gene expression studies cannot be performed to help us further understand or manipulate the organism. Here we report the genetic transformation of a heliobacterium, which should enable future genetic studies in this unique phototrophic organism.

Original languageEnglish
JournalApplied and environmental microbiology
Volume85
Issue number19
DOIs
Publication statusPublished - Oct 1 2019

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Heliobacterium
Heliobacteriaceae
Genetic Transformation
Genetic Vectors
molecular biology
genetic vectors
Molecular Biology
Plasmids
autotrophs
genetic transformation
Bacteriochlorophylls
Genetic Techniques
Nitrogen Fixation
Gene Knockout Techniques
Deoxyribonucleases
Poisons
Host Specificity
organisms
plasmids
Methyltransferases

Keywords

  • conjugation
  • DNA methylation
  • heliobacteria
  • restriction

ASJC Scopus subject areas

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

Cite this

A Molecular Biology Tool Kit for the Phototrophic Firmicute Heliobacterium modesticaldum. / Baker, Patricia L.; Orf, Gregory S.; Khan, Zahid; Espinoza, Levi; Leung, Sabrina; Kevershan, Kimberly; Redding, Kevin Edward.

In: Applied and environmental microbiology, Vol. 85, No. 19, 01.10.2019.

Research output: Contribution to journalArticle

Baker, Patricia L. ; Orf, Gregory S. ; Khan, Zahid ; Espinoza, Levi ; Leung, Sabrina ; Kevershan, Kimberly ; Redding, Kevin Edward. / A Molecular Biology Tool Kit for the Phototrophic Firmicute Heliobacterium modesticaldum. In: Applied and environmental microbiology. 2019 ; Vol. 85, No. 19.
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