2026-09-18T17:51:22Zhttps://publikationen.uni-tuebingen.de/oai/request
oai:publikationen.uni-tuebingen.de:10900/1807882026-06-16T01:00:48Zcom_10900_42126col_10900_42133
Publikationssystem UB Tuebingen advisor Forchhammer, Karl (Prof. Dr.) author Aries von Manteuffel, Nathan Matthias 2026-06-15T08:15:53Z 2026-06-15 http://hdl.handle.net/10900/180788 The use of herbicides over the last 80 years has been a constant driver of global food production. Specifically, the development of glyphosate-containing herbicides, most notably Roundup®, has significantly impacted global food security. Glyphosate is a selective inhibitor of the essential shikimate pathway in plants, bacteria, and fungi. With increasing critical research into the safety of glyphosate and the emergence of glyphosate-resistant weeds, the search for alternative herbicides has intensified in recent years. Since herbicides are essential to global food production and security, finding alternatives to glyphosate is of great importance. A promising candidate in this search is the bioactive sugar 7-deoxy-sedoheptulose (7dSh). 7dSh is naturally produced by Synechococcus elongatus and Streptomyces setonensis. It has been identified as an inhibitor of the shikimate pathway in plants and cyanobacteria, just like glyphosate. These findings have positioned 7dSh as a promising alternative to glyphosate. However, questions remain about additional working mechanisms and more economical and efficient methods of 7dSh production. In this work, Streptomyces setonensis was used to produce 7dSh in 20 L bioreactors, achieving concentrations of up to 1 g/l. A novel purification protocol was developed that yields 7dSh with high purity using cost-effective, scalable methods. The development of an economically scalable production of 7dSh ensures sufficient supply for future work and provides a basis for the development of potential industrial applications. A mutant in the highly sensitive strain Trichormus variabilis was found to show no sensitivity to 7dSh. Multi-sequence alignment revealed mutations in genes previously not linked to 7dSh activity. Although further research is needed, these findings open new avenues for investigating 7dShs' working mechanisms. Furthermore, it was shown that 7dSh must be phosphorylated after uptake to be bioactive. Work on chlorotic cells revealed that 7dSh is a potent inhibitor of both glycogen production and consumption. Furthermore, CO2 flux measurements showed that 7dSh inhibits CO2 fixation as early as 100 minutes after application. Lastly, 7dSh was shown to strongly influence glutamate pools in chlorotic and vegetative cells. These findings cannot be attributed to inhibition of the shikimate pathway and therefore must result from yet unknown working mechanisms. Based on these findings, this work suggests that 7dSh is not a selective inhibitor of the shikimate pathway alone, but rather a potent disruptor of central carbohydrate and nitrogen metabolism. en ubt-podno 7dSh – a Natural Sugar from Cyanobacteria as a Sustainable Herbicide PhDThesis URL https://publikationen.uni-tuebingen.de/xmlui/bitstream/10900/180788/2/Dissertation%20Nathan%20Aries%20von%20Manteuffel%20PDFA.pdf File MD5 1f0120e165f402cd8fd3c50c4cd7a969 8408415 application/pdf Dissertation Nathan Aries von Manteuffel PDFA.pdf URL https://publikationen.uni-tuebingen.de/xmlui/bitstream/10900/180788/4/Dissertation%20Nathan%20Aries%20von%20Manteuffel%20PDFA.pdf.txt File MD5 485087c0dde318480aadfddbabe490f1 173622 text/plain Dissertation Nathan Aries von Manteuffel PDFA.pdf.txt