Symbiont Conversion is a term that refers to the transformation of normally parasitic organisms into a symbiotic relationship with a host. It is the theory that microorganisms and cells that are often considered parasites can be "educated" and converted into symbionts, partners that live together for mutual benefit. A symbiosis is a living community in which two different species are closely related to each other and at least one species derives an advantage from the relationship. By contrast, parasitism signifies a relationship in which one organism (the parasite) lives at the expense of another (the host) without benefiting the latter. Symbiont Conversion is the idea that an organism normally considered a parasite can be converted into a symbiotic relationship with a host through certain processes. This contrasts with traditional approaches that focus on eliminating or destroying pathogens. The theory suggests that instead of solely employing methods like chemotherapy or antibiotics (which can harm healthy cells), we can reprogram these organisms to become beneficial to the host.
Theoretical basis: The Symbiont Conversion Theory postulates that it is possible to influence parasites in such a way that they develop into symbionts and make a positive contribution to the host. This could be done, for example, by specifically modifying the genetic or physiological characteristics of the parasite or by creating an environment that favours the development of a symbiotic relationship.
Examples and applications: Although Symbiont Conversion is still a relatively new concept, there are already theoretical considerations and initial experimental approaches as to how this could be achieved. Possible applications could be in medicine, agriculture and environmental technology. For example, harmful bacteria could be converted into beneficial bacteria through Symbiont Conversion, which could be used to treat diseases or improve soil quality. In theory, Symbiont Conversion might also be a solution to antimicrobial resistance, as well as an alternative way to treat cancer. In essence, Symbiont Conversion Theory offers a paradigm shift in how we approach disease treatment, suggesting that we can harness the power of symbiosis to create healthier interactions between organisms, rather than solely focusing on eradication.
Basically a literature survey shows that there are two different approaches towards the reprogramming of bacteria: On the one hand, bacteria can be reprogrammed by altering their genes, for example by using bacteriophages (viruses that target bacteria) or methods like CRISPR/Cas9. These approaches are usually conducted ex vivo. On the other hand, there is metabolic reprogramming: by adding certain substances to the bacteria, the behavior of the bacteria is modified. This can even be done in vivo. For true Symbiont Conversion, it seems an in vivo approach would be more desirable, as the objective is to “cure” living patients. However, this might perhaps be only possible by extracting bacteria from the human organism, modifying them ex vivo and then inserting them into the human organism again.
The term Symbiont Conversion was coined by Claus D. Volko. He was a member of Dr. Uwe Rohr's research group, which investigated the working mechanisms of isoflavones in the human body. Rohr's main hypothesis was that isoflavones helped convert a particular bunch of steroid hormones which he called stress hormones into another bunch which he called immunity hormones. He also hypothesized that isoflavones have a beneficial effect for cancer patients because they convert cancer cells back into regular tissue. This inspired Volko to extend the hypothesis to all sorts of parasitic cells - thus Symbiont Conversion Theory was born. Because of the historical relevance, some of Rohr's publications are listed below as well.
Claus Volko: Reprogramming Bacteria for Symbiont Conversion: A Review (2025)
Claus Volko: Converting parasites into symbionts (2024)
Claus Volko: Symbiont Conversion Theory (2018)
Claus Volko: Hormones, Stress and Immunity (2013)
Claus Volko: Hormone und ihre Wirkung auf Stress und Immunsystem (2013)
Uwe Rohr et al.: Cancer protection of soy resembles cancer protection during pregnancy (2010)
Uwe Rohr et al.: Phytoestrogens from red clover (2005)
Reversing cancer? New gel converts tumour cells to stem cells in 24 Hours
Dr. Jessica Sacher, Ph.D. - Co-Founder, Phage Directory - Unlocking The Potential Of Phage Therapy
(Phages are a possible way to inject genes into bacteria and thus reprogram them.)
Dr. Noel Gahamanyi, Ph.D. - Rwanda Biomedical Centre - One Health To Curb AMR & Zoonoses
Darmbakterien und Viren als Schlüssel für ein langes Leben
(Quote: "Besonders bestimmte Viren beeinflussen laut Simon Rasmussen das Darmmikrobiom des Menschen und damit dessen Gesundheit laut der Studie positiv.")
Exosome-delivered AGO2–siRNA complexes
(By packaging human Argonaute 2 (AGO2) along with an siRNA into exosomes, researchers have been able to get a functional RISC into Staph. aureus. Once inside, the AGO2-siRNA complex binds the target mRNA (e.g. mecA) and blocks its translation-converting MRSA into methicillin-sensitive bacteria in mice. Thanks to Abdullah Al Mamun for contributing this link!)
Phage- or plasmid-delivered bacterial sRNAs
(Bacteriophages (or phagemids) can carry synthetic small regulatory RNAs (sRNAs) - not true siRNAs, but short antisense transcripts - into E. coli to block translation of resistance enzymes (e.g. chloramphenicol acetyltransferase). This has restored antibiotic sensitivity in vitro. Thanks to Abdullah Al Mamun for contributing this link!)
A New Method of Modifying Stem Cells
How AI is reviving a century-old solution against antibiotic resistance
How viruses can help the fight against antibiotic resistance
COVID-19 Vaccine's mRNA Technology Adapted for First Antibiotic-Resistant Bacteria Vaccine
Korean Researchers Turn Cancer Cells Back Into Normal Cells
Claus D. Volko, July 10, 2025