Antibiotic-free Bacterial Fermentation

Gen-H developed an antibiotic-free plasmid maintenance system that offers a superior alternative to antibiotic-based plasmid maintenance.


Benefits of the Gen-H antibiotic-free fermentation system:

  • Cost-efficient – no antibiotic supplmentation necessary, no purification or analytic steps needed to ensure the product is antibiotic free
  • Reduced metabolic load for host cells – eliminating expression of an antibiotic resistance marker can result in higher productivity
  • No antibiotics in the fermentation – prevents consumer exposure to antibiotics
  • No antibiotic genes in process – prevents development of antibiotic-resistant bacteria through horizontal gene flow
  • Flexible – one strain can be used with different fermentation plasmids without requiring helper plasmids or genetic engineering
  • Highly compatible – compatible with all strain backgrounds, media, fermentation temperatures and expression systems
  • Adaptable – existing strains and processes can be converted to the antibiotic-free system

The Gen-H plasmid maintenance system is completely independent of antibiotics: there are no antibiotics needed in the culture and no antibiotic resistance genes in the cells.

This patented technology uses conditional complementation. An essential endogenous gene in the fermentation strain is replaced with an inducible genomic copy of the same gene. In the absence of the inducer, cells are dependent on a plasmid with a constitutively expressed copy of the essential for growth, ensuring optimal plasmid maintenance. Importantly, expression of the genomic copy of the essential gene can be induced so that the bacterial strain can be propagated without a plasmid, allowing the strain to be easily transformed with a new plasmid without cumbersome strain modifications or helper plasmids.

 Interested? Please contact us for more information.

For the detailed report and supporting data, take a look for yourself at our publication:



We have filed two patents for this technology:

EP21174990: Microorganism strain and method for antibiotic-free plasmid-based fermentation, 20 May 2021
EP22160310: Microorganism strain for antibiotic-free plasmid-based fermentation and method for generation thereof, 04 March 2022

For more information please contact our service team in Heidelberg, Germany: contact (at)


Gen-H Genetic Engineering Heidelberg GmbH
Im Neuenheimer Feld 584
69120 Heidelberg

Phone : +49 6221 1370811
contact (at)

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Gen-H Genetic Engineering Heidelberg GmbH
Im Neuenheimer Feld 584
69120 Heidelberg