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Artificial Life Scientists aroused synthetic bacteria
About six years ago, American researchers presented a bacterium with completely artificially synthesized genetic material. The speech was even of "artificial life". The scientists have now taken another step: They produced a bacterium that contains only absolutely vital genes.
How many genes a living creature really needs
A total of 473 genes needs a living being at least. At least this is true for bacteria, as US researchers have discovered around Craig Venter. The scientists of the "J. The Craig Venter Institute and colleagues from the University of California-San Diego, Synthetic Genomics, and the National Institute of Standards and Technology report in the journal Science that these genes control all vital processes under optimal environmental conditions Let bacteria grow. As a report in the scientific journal "Nature" shows, the researchers had designed bacteria with an artificially generated minimal genetic material and allowed to grow in the laboratory. According to a news agency dpa, the genome of the bacterium named "JCVI-syn3.0" is smaller than that of any natural, autonomously replicating cell. According to this, it is easier to investigate which genes and which functions are essential for life.
American researchers have created a bacterium with a minimal genome that only contains absolutely vital genes. (Image: blobbotronic / fotolia.com) Results are "not so relevant" according to German experts
According to current estimates, a human has more than 20,000 genes, many animals and plants have even more. The biotechnologist Prof. dr. According to dpa, Alfred Pühler from the University of Bielefeld explained that the study was a good piece of scientific work, but not the big hit that many experts had expected. "Biotechnologically, the result is not so relevant," said the German scientist. Although the study was carefully derived and the result of great diligence. "But it does not provide the simple chassis for the production of substances, as you had hoped," said Pühler.
Search for bacterial minimal genome
As early as 2010, a team led by Craig Venter had created a bacterium with artificial genetic material. It is said that the genes of the bacterium Mycoplasma mycoides were reproduced with the help of individual genome fragments and this art genome was then used in another bacterial species (Mycoplasma capricolum). According to the information, the synthetic genetic material displaced the original genetic material and took over the control of the host bacteria. In their study, the researchers downsized the genome of this bacterium called "JCVI-syn1.0". The aim of the study was to find a bacterial minimal genome sufficient for maintaining life.
Bacterium not viable in first attempts
Based on basic molecular biological knowledge and existing data on gene functions, the scientists designed this genome in initial experiments on the computer. However, they failed and the resulting bacterium proved to be non-viable. They started again with the natural genupfen genome. "The results convinced us that we do not have enough knowledge to design a functioning minimal genome based on basic principles," the researchers said. Therefore, in the subsequent experiments, they experimentally went about their work: they gradually silenced individual genes to find out if they were necessary for the functioning of the bacterial cell.
Unknown functions essential to life
In this way, they identified three groups: genes that are indispensable, genes that are dispensable, and genes that greatly enhance the prosperity of cells. Eventually, 473 genes remained, keeping JCVI-syn3.0 alive under laboratory conditions. The bacteria were supplied with necessary nutrients in the culture. As the study says, under less optimal conditions, more genes are likely to be needed for survival. A total of 149 genes, the researchers could not attribute a biological function. According to the experts, this suggests that there are hitherto unknown functions that are essential for life. Although the creation of a minimal genome was her goal, her approach could also be used to construct cells with desired properties. For example, cells could be built with additional metabolic pathways or altered genetic code to produce drugs or industrial chemicals.
Great performance of the research team
"However, one has to ask oneself: is that really the ideal bacterium for the synthesis of biotechnologically relevant substances?" Said Pühler, who was not involved in the study. Among other things, the benefit for biotechnological production is reduced by the fact that the mycoplasma produced proliferated too slowly. In addition, the result can not be transferred to other microbes. "For other bacteria, I will end up with other basic gensets." According to Pühler, the mycoplasma gave the team the great advantage of having comparatively few genes by nature. "They live as beneficiaries in other cells and do not have to produce many important substances themselves," he said dpa. Nevertheless, the researchers' performance was high: "The genome was nearly halved." In addition, the 149 non-assignable genes would offer interesting research approaches. (Ad)