Achromatium oxaliferum is the largest (known) freshwater bacterium in the world. It is 30,000 times larger than its “normal” counterparts that live in water and owing to its calcite deposits it is visible to the naked eye. It has long been known – at least among bacteria fans – that some sulphur bacteria such as Achromatium can be extremely large and may contain several genome copies. But the fact that a single bacterial cell harbours hundreds of different(!) genomes is new – also to bacteria aficionados.
Although Achromatium oxaliferum has been known for over a century, its physiology and genetic features remain largely unknown.
Fluorescence in-situ hybridization image of a stained Achromatium oxaliferum cell.
Image: Mina Bizic-Ionescu / IGB
A team of researchers from the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB) in Berlin, the Carl von Ossietzky University in Oldenburg and Oxford University found that single cells of Achromatium contain up to 300 DNA spots, each with an undefined number of chromosomes. Single-cell genomes and metagenomic analysis showed that the many chromosomes are not identical copies of one another.
A new dawn for bacteria researchers
Usually environmental samples – such as water or soil samples – are analysed using DNA/RNA sequences. In this process, the different sequences shed light on the types of bacteria contained in a sample. If it is assumed that a polyploid bacterium of a certain type has multiple identical genomes, then the number of different types of bacteria in a water sample will be that of the different genomes.
If, however, the sample also contains Achromatium or similar polyploid bacteria, the method used to date may lead to an overestimation of the true diversity. Where 1000 different bacterial types were once assumed, perhaps there are only 100 or less.
Only a few years ago, it was still believed that single-celled organisms with several genome copies were the exception. In the meantime, however, such organisms are increasingly being “discovered”. The new insights into Achromatium oxaliferum could, therefore, also give an impetus to taking a closer look at cells with few to hundreds genome copies to ascertain whether they are in fact identical copies.
Same same but different
When an Achromatium cell divides, the genomes are likely distributed “randomly” to the daughter cells. This random division should actually cause the new cells to become increasingly dissimilar. And yet how does Achromatium manage to remain the same nonetheless? Strong environmental pressure leads to the preservation of functionality, ensuring the “survival” of Achromatium: mother cells and daughter cells remain the same organisms.
Have a look at the scientist’s blog article on Nature Microbiology to deepen the topic: https://naturemicrobiologycommunity.nature.com/channels/346-behind-the-paper/pos...
Danny Ionescu, Mina Bizic-Ionescu, Nicola De Maio, Heribert Cypionka, Hans-Peter Grossart (2017): Community-like genome in single cells of the sulfur bacterium Achromatium oxaliferum, Nature Communications 8, Article number: 455 (2017), doi:10.1038/s41467-017-00342-9. http://rdcu.be/vCoK
Dr. Danny Ionescu, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Dept. Experimental Limnology, email@example.com, +49 (0) 162 9702 888
Prof. Hans-Peter Grossart, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Dept. Experimental Limnology, firstname.lastname@example.org, +49 (0) 33082 699 91/10
About the Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB):
Work at IGB combines basic research with preventive research as a basis for the sustainable management of freshwaters. In the process, IGB explores the structure and function of aquatic ecosystems under near-natural conditions and under the effect of multiple stressors. Its key research activities include the long-term development of lakes, rivers and wetlands under rapidly changing global, regional and local environmental conditions, the development of coupled ecological and socio-economic models, the renaturation of ecosystems, and the biodiversity of aquatic habitats. Work is conducted in close cooperation with universities and research institutions from the Berlin/Brandenburg region as well as worldwide. IGB is a member of the Forschungsverbund Berlin e.V., an association of eight research institutes of natural sciences, life sciences and environmental sciences in Berlin. The institutes are members of the Leibniz Association. http://www.igb-berlin.de
Katharina Bunk | idw - Informationsdienst Wissenschaft
Rochester scientists discover gene controlling genetic recombination rates
23.04.2018 | University of Rochester
One step closer to reality
20.04.2018 | Max-Planck-Institut für Entwicklungsbiologie
Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.
Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
23.04.2018 | Physics and Astronomy
23.04.2018 | Physics and Astronomy
23.04.2018 | Trade Fair News