Genetically engineered microorganisms with improved properties are of vital interest in the advancement of modern medicine, as well as the agriculture and food industry. Biotechnology enables modification of specific genes in an organism to produce desirable properties—for example, the ability to withstand extreme environmental conditions or to catalyze a chemical reaction—but modifying complex traits can be time-consuming and expensive due to the large number of genes involved.
Hua Zhao and co-workers at the A*STAR Institute of Chemical and Engineering Sciences1 have now developed a technique called error-prone whole genome amplification (WGA) that enables modification of numerous genes at the same time. To illustrate the potential of the new technique, the researchers applied it to create yeast cells capable of surviving high levels of ethanol.
Metabolism of ethanol in yeast is a complex trait that requires the action of 40 to 60 genes. The researchers isolated DNA from Saccharomyces cerevisiae—one of the most useful forms of yeast widely used in baking and brewing since ancient times—and copied it using the powerful polymerase chain reaction (PCR) technique that amplifies DNA sequences. The key to error-prone WGA is the introduction of random DNA copying errors through imperfect reaction conditions during PCR. The researchers established the mutagenic reaction conditions by adding gene-damaging manganese chloride to the reaction mixture in order to produce DNA with plenty of mutations.
Zhao and co-workers introduced copies of mutated DNA back into S. cerevisiae—a process known as transformation. Normal yeast cells are capable of surviving on a medium containing 7% ethanol. The transformed cells were grown on a medium initially comprising 8.5% ethanol.
The researchers harvested DNA from cells that survived on the high-ethanol medium, and then repeated the error-prone PCR and transformation cycle twice. By the third cycle, cells that were able to survive on a medium containing 9% ethanol had been isolated. The method is an example of directed evolution, which uses the power of natural selection to speed up the process of adapting to changes in environmental conditions in order to develop microorganisms with properties that are biotechnologically useful.
Error-prone WGA is unique in that its direct manipulation of DNA in vitro is slower and more complex than in vivo methods. “The new method enables rapid evolution of complex phenotypes of microorganisms”, says Zhao, whose team has already begun to characterize the proteins and genes in the ethanol-tolerant yeast cells using proteomic and whole genome studies. In future, error-prone WGA may also be extended to other microorganisms.
Luhe, A. L., Tan, L., Wu, J. & Zhao, H. Increase of ethanol tolerance of Saccharomyces cerevisiae by error-prone whole genome amplification. Biotechnology Letters 33, 1007–1011
A Map of the Cell’s Power Station
18.08.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
On the way to developing a new active ingredient against chronic infections
18.08.2017 | Deutsches Zentrum für Infektionsforschung
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
16.08.2017 | Event News
04.08.2017 | Event News
26.07.2017 | Event News
18.08.2017 | Life Sciences
18.08.2017 | Physics and Astronomy
18.08.2017 | Materials Sciences