EXPO 40 years BCCM: Model organisms

Scientists cannot hope to learn everything about every organism, so they study just a handful of examples in detail. These well- studied creatures are called model organisms.

Escherichia coli is the undisputed bacterial superstar among model microorganisms and has become a vital tool for biotechnology.

Saccharomyces cerevisiae, which notably raises the dough of your bread, fulfills the same role among yeasts.

Bacteria Diatoms Fungi Mycobacteria Plasmids



Escherichia coli

E. coli is the undisputed bacterial superstar of the model microorganisms. E. coli is has been used in many experiments that helped us to understand how bacteria work: how they eat, how they reproduce, questions about their genes and their proteins—about almost everything. So, in a way, it can be said that modern microbiology has been built upon E. coli’s “shoulders.”




Cyclotella meneghiniana

Seminavis robusta

Cyclotella meneghiniana and Seminavis robusta

One of the unique characteristics of diatoms is that their cell wall (frustule) is made of a very hard material, this being, opal. This frustule exists out of a hypotheca (box - lower half) and an epitheca (lid – upper half) that are connected to each other by girdles. The hypotheca is a little bit smaller than the epitheca. When diatoms divide mitotically, one cell gives rise to 2 new cells.

During this process, in the lid of the parental cell, a new box will be formed and in this way create a new cell. The box side of the parental cell will act as the lid for the second newly formed cell and will this form another, smaller box. As a consequence, one of the new cells will be smaller than the parental cell. This means that after many generations, the diatom population will be very small, so small that they will not be able to divide successfully anymore. To increase in size again, sexual reproduction is often required. The reproduction in diatoms is complex and not all details have been discovered yet. During the sexual phase, after the fusing of the gametes, an auxospore will be formed. In this auxospore, a larger initial cell will be created. Cyclotella meneghiniana (centric diatoms) and Seminavis robusta (pennate diatoms) are often used as model organisms to study the sexual reproduction in these fascinating microalgae.

In search of new tractable diatoms for experimental biology. Chepurnov et al., BioEssays (2008).





Saccharomyces cerevisiae

Baker’s yeast, or Saccharomyces cerevisiae as it is also known, is among the best-studied experimental organisms. It is one of the simplest eukaryotic organisms, with a genome that has been published already in 1996.

Studying the biology of this yeast has enabled scientists to work out the connections between genes and proteins, and the functions they carry out in our cells. Although it may seem that yeast and humans have little in common, yeast cells share many basic biological properties with our cells. Genetic manipulation in yeast is easy and cheap compared to similar experiments in more complex animals such as mice and zebrafish. At least 20% of human genes known to have a role in disease have counterparts in yeast. This suggests that such diseases result from the disruption of very basic cellular processes. For example, genes involved in yeast cell division are mutated in human cancers. Yeast also shares some genes with humans, which means to some extent, they can be used to test new drugs. Thousands of drugs can be tested on yeast cells containing mutated human genes to see if the drugs can restore normal function. The genes with the most similarities shared between humans and yeast, are the MSH2 and MLH1 genes. These genes are involved in hereditary non-polyposis colorectal cancer in humans. Examining these genes in yeast helps scientists to learn more about the role of these genes in colon cancer.





Mycobacterium smegmatis

Mycobacterium smegmatis has emerged as a valuable surrogate organism for evaluating potential drug candidates against pathogenic mycobacteria, including the Mycobacterium tuberculosis complex. Despite being non-pathogenic to humans, M. smegmatis shares significant genetic and physiological similarities with its pathogenic counterparts, making it an ideal model organism for drug discovery and development. Researchers have leveraged the ease of genetic manipulation and fast growth rate of M. smegmatis to screen libraries of chemical compounds and assess their effectiveness against mycobacterial infections. By studying the response of the surrogate to these compounds, researchers can gain insights into the compounds' mechanisms of action, toxicity profiles, and potential efficacy against pathogenic mycobacteria. While not being perfect attributable to differences in virulence factors and drug susceptibility between species, M. smegmatis remains a valuable tool for early-stage screening and identification of promising drug leads in the fight against tuberculosis and other mycobacterial infections.


Mycobacterium tuberculosis reference strains

Since 2013, the TDR-TB Strain Bank, a part of BCCM/ITM and under the World Health Organization's umbrella, has served as a pioneering public repository, supporting drug-resistant tuberculosis research and advances in diagnostics. In addition, this bank is ensuring laboratory quality control through its exceptional assortment of drug-resistant Mycobacterium tuberculosis strains. finally, it also plays a crucial role in the annual proficiency panel testing for the Tuberculosis Supranational Reference Laboratory network (SRLN).





Minimized plasmids are essential for molecular biology. The BCCM/GeneCorner Plasmid Collection presents the smallest high-copy cloning vector to date: pICOz (LMBP 11103) Minivectors are highly efficient for mammalian cell transfection, for the assembly of building blocks in synthetic biology, PCR-based mutagenesis and even in vivo genetherapy. With only 1185 basepairs while still having an extended multiple cloning site, pICOz is the ideal workhorse for many applications in biotechnology.

Engineering a minimal cloning vector from a pUC18 plasmid backbone with an extended multiple cloning site. Staal et al., Biotechniques (2019)