Planctomycetes puzzle solved:

Conventional wisdom on missing cell wall in these unusual bacteria refuted

Planctomycetes are extraordinary bacteria that are found worldwide, but have been relatively little studied. Since the beginning of the 1990s, researchers have assumed that Planctomycetes do not possess a typical bacterial cell wall made from peptidoglycan. Using the latest techniques, scientists at Leibniz Institute DSMZ – German Collection of Microorganisms and Cell Cultures GmbH now successfully demonstrated, contrary to this conventional wisdom, that Planctomycetes do have a peptidoglycan cell wall. Today, the results of their collaboration with the Max Planck Institute of Biochemistry, Martinsried, with Eberhard Karls University Tuebingen, and with the Helmholtz Centre for Infection Research, Braunschweig, were published in Nature Communications, a prestigious online journal.

Planctomycetes, when first discovered in 1924, were originally thought to be fungi. Not until the 1970s were they recognized as bacteria—and even after that they continued to puzzle scientists. It soon became clear that they were different from all other known bacteria. “Planctomycetes hold a special position in the bacterial kingdom, and they are unique in many ways,” said Christian Jogler, head of the junior research group “Microbial Cell Biology and Genetics” at DSMZ. “These bacteria combine the characteristics of various organisms in a very unusual manner. They reproduce by budding paralleling yeasts, and a compartmentalized cell plan -comparable to highly evolved animal or plant cells- was proposed. In addition, until now they were assumed to lack a peptidoglycan cell wall. This assumption supported the hypothesis that Planctomycetes potentially were predecessors of complex eukaryotic cells.”

Now, Olga Jeske, a doctoral student in Christian Jogler's team at DSMZ, made a very surprising discovery: She was able to prove that Planctomycetes possess a peptidoglycan cell wall after all, which makes them rather similar to Gram-negative bacteria. In her close collaboration with scientists at the Max Planck Institute of Biochemistry, Martinsried, at Eberhard Karls University Tuebingen, and at the Helmholtz Centre for Infection Research, Braunschweig, state-of-the-art methods such as high-resolution microscopy, mass spectroscopy, and biochemical detection techniques were essential.

“The discovery of a peptidoglycan cell wall invalidates the opinion still prevalent in our textbooks, namely that Planctomyctes are substantially different from other bacteria,” explains Christian Jogler, putting this new scientific finding in perspective. “Normally, you expect to find such a cell wall in all free-living bacteria, as it provides protection against environmental impact.”

The findings of the German researchers are confirmed by an independently conducted study by Laura van Niftrik and Boran Kartal of Radboud University Nijmegen in the Netherlands. The Dutch researchers published their results, obtained with different methods in different planctomycetal model organisms, at the same time. “We will have to wait for further studies, but these findings indicate that Planctomycetes are most likely not the predecessors of complex eukaryotic cells,” said Christian Jogler.

“We are proud that these important scientific results came out of one of our junior research groups here at DSMZ,” said Jörg Overmann, director of DSMZ.  “We will continue to support research that utilizes the latest in cutting-edge technology.  As Planctomycetes are important for the global nitrogen and carbon cycles, and they produce a number of natural substances that potentially may be used as medicines in the future.”


For further information please visit the DSMZ website