On August 28, 2026, Philemon Orwa successfully defended his doctoral dissertation at Technische Universität Darmstadt, graduating with the overall grade “very good” and thereby earning the academic degree Doctor of Natural Sciences (Dr. rer. nat.).
His dissertation, entitled “Exploring the microbiome of tomato: implications for plant health in the context of Phytophthora infestans,” was carried out as part of a DAAD-funded research project at the Institute for Biological Control (BI) in cooperation with Embu University in Kenya.
Philemons research focused on controlling Phytophthora infestans, the causal agent of late blight in tomatoes, through the use of microbial antagonists. In that context, he isolated more than 1000 fungi and bacteria from tomato soils and tomato-associated tissues. He subsequently investigated these microorganisms individually and in consortia for their antagonistic effects against P. infestans and other tomato-related pathogens under laboratory, greenhouse, and field conditions. In parallel, he characterized the microbiome of soil and plant samples in relation to the occurrence of Phytophthora infestans and compared samples from different soil origins.
Through his research, Philemon made an important contribution to understanding the role of the tomato microbiome in plant health and to the development of sustainable biological control strategies for organic and integrated crop production.
We warmly congratulate Philemon on this outstanding achievement and wish him continued success and fulfillment in both his personal life and his scientific career!
References
Orwa, P., Kuhl-Nagel, T., Meinhold-Ernst, R., Seyer, A., Jehle, J. A. , Mwirichia, R., Linkies, A. (2025). Chaetomium, Chlonostachys, and Pseudogymnoascus isolates from tomato tissues significantly suppress Phytophthora infestans in tomato. PLOS ONE 20(10): e0335007. doi.org/10.1371/journal.pone.0335007
Orwa, P., Kuhl-Nagel, T., Meinhold-Ernst, R., Jehle, J. A., Mwirichia, R., Linkies, A. (2026). Linking microbiome structure to functional analysis identifies resilient Pseudarthrobacter, Pseudomonas, and Streptomyces antagonists of Phytophthora infestans in tomato. Front. Microbiol. 17:1810932. doi: 10.3389/fmicb.2026.1810932