Jan Andersson

Senior Lecturer/Associate Professor at Department of Cell and Molecular Biology; Molecular Evolution

Mobile phone:
+46 70 167 95 98
Visiting address:
Husargatan 3
752 37 UPPSALA
Postal address:
Box 596
751 24 UPPSALA

Short presentation

I am a senior lecturer in microbial evolutionary genomics. Since the early 10s, I have been heavily involved in teaching and teaching issues in the role of program director for the MSc program in molecular biotechnology engineering.

My research is about how changes in the genome facilitate evolutionary adaptations to new environments in eukaryotic microorganisms, a process for which I have contributed to the understanding that horizontal gene transfer from bacteria plays an important role.


  • anaerobic protists
  • comparative genomics
  • diplomonads
  • evolutionary genomics
  • horisontell genöverföring
  • horizontal gene transfer
  • lateral gene transfer
  • microbiology
  • mikrobiologi
  • molecular evolution
  • molekylär bioteknik
  • programutveckling


I grew up in Björklinge, north of Uppsala, and began my university studies at Uppsala University in 1990. In the following years, I studied mathematics and natural sciences. I did a one year's military service and a six-month ERASMUS exchange to Sussex University in Brighton before I started my doctoral studies in the fall of 1995. I studied how intracellular bacteria of the genus Rickettsia evolved, with Siv Andersson and Charles Kurland as supervisors.

During my PhD, I was able to demonstrate that the genome contained genes that had lost their function, so-called pseudogenes. It was a phenomenon known to exist in eukaryotes at the time but many in the research field doubted that pseudogenes existed in bacteria. I also contributed to the genome sequence of Rickettsia prowazekii, which was the first complete genome published by a Swedish group, and the 18th in the world.

After the defense in December 1999, I was a postdoc for three years at Dalhousie University in Halifax, Nova Scotia, Canada with a Wennergren scholarship. Ford Doolittle and Andrew Roger were my supervisors. I studied the role of horizontal gene transfer between prokaryotes and eukaryotes in the evolution of microbial eukaryotes. It became clear early on to me, and my supervisors, that it was an important process that was largely neglected by the research field.

When I returned to Uppsala in 2003 as a Assistant professor, I continued the studies of genome evolution of protists, with a particular focus on the role of horizontal gene transfer. During the 00s, I published a series of papers that, along with studies from other groups, slowly built acceptance in the research field that horizontal gene transfer is an aspect of genome evolution that should not be ignored in studies of eukaryotic microorganisms.

Since the late 00s, the focus has shifted more towards the evolution of diplomonads, a group of eukaryotic microorganisms found in oxygen-poor environments. We study Giardia lamblia, which causes diarrhea in humans, but also the fish parasite Spironucleus salmonicida and the free-living Trepomonas and Hexamita inflata. Questions we studied include e.g. whether different isolates of Giardia are different species, how the defense against oxygen and oxygen radicals has evolved in diplomonads and their relatives and how the secondarily free-living diplomonads have been able to adapt to a life independent of a host organism.

Since the 10th century, I have been heavily involved in teaching and program development. I have worked a lot with project courses in addition to teaching traditional courses in bioinformatics and molecular biology. In these courses, I have developed structures to involve external actors from industry and authorities as clients of projects.

I was program director for the MSc program in Molecular biotechnology engineering during 2013-2021. During that time I, together with the program council and departments, reviewed and restructured the entire program with the aim of strengthening the progression, the achievement of program goals and the matching with the industry. The work resulted in a mandatory block of courses in years 1-3 followed by three different profiles in years 4 and 5 during which the students can select their individual specialisation. Together with IBG and the program council, I introduced an ethics track that runs through the entire program. Since 2022, I am deputy program


The overall goal of our research is to understand how different evolutionary processes acting on the genomic level have changed, and still are changing, the biology of microbial eukaryotes. We focus on diplomonads, a peculiar group with the genetic material divided into two separate nuclei in the cell. Knowledge from our research gives a deeper understanding of the origin and evolution of parasites, and the role of eukaryotic microbes in natural environments.

I am using a diplomonads, a group of microorganisms as a model since many years. We are using sequencing technology to do whole genome sequencing of different diplomonads. Using bioinformatic tools we identify differences and similarities within the group, as well as between diplomonads and other organisms. Then we are trying to couple differences in the genome to variations in the biology.

The group diplomonads both contains parasites which, for example, infect humans (e.g. Giardia lamblia) and fish (e.g. Spironucleus salmonicida), but also species that do not cause disease in the host, and free-living species such as Trepomonas and Hexamita inflata. We have shown that diplomonads have adapted to oxygen-poor environments by acquisition of genetic material from other organisms. We have also demonstrated the presence of hydrogenosomes, hydrogen-producing organelles, in some diplomonads and that the free-living diplomonads have evolved from organisms that were dependent on a host organism. Horizontal gene transfer from the bacteria taken up as food by the eukaryote has contributed to the adaptation to a life outside the host organism.


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Jan Andersson