Generating microbes with useful properties is quicker, easier if multiple genes are modified at the same time

Oct 13, 2011

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 Sciences have now developed a technique called error-prone whole genome amplification (WGA) that enables modification of numerous at the same time. To illustrate the potential of the new technique, the researchers applied it to create 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 .

Explore further: Improving the productivity of tropical potato cultivation

More information: 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

Provided by Agency for Science, Technology and Research (A*STAR)

not rated yet
add to favorites email to friend print save as pdf

Related Stories

Making tomorrow's bioenergy yeasts strong

Aug 25, 2011

Cornstalks, wheat straw, and other rough, fibrous, harvest-time leftovers may soon be less expensive to convert into cellulosic ethanol, thanks to U.S. Department of Agriculture (USDA) scientists' studies of a promising new ...

Sugar-hungry yeast to boost biofuel production

Mar 29, 2010

Engineering yeast to transform sugars more efficiently into alcohols could be an economically and environmentally sound way to replace fossil fuels, say scientists presenting at the Society for General Microbiology's spring ...

Recommended for you

Building better soybeans for a hot, dry, hungry world

8 hours ago

(Phys.org) —A new study shows that soybean plants can be redesigned to increase crop yields while requiring less water and helping to offset greenhouse gas warming. The study is the first to demonstrate ...

Gene removal could have implications beyond plant science

8 hours ago

(Phys.org) —For thousands of years humans have been tinkering with plant genetics, even when they didn't realize that is what they were doing, in an effort to make stronger, healthier crops that endured climates better, ...

Chrono, the last piece of the circadian clock puzzle?

22 hours ago

All organisms, from mammals to fungi, have daily cycles controlled by a tightly regulated internal clock, called the circadian clock. The whole-body circadian clock, influenced by the exposure to light, dictates the wake-sleep ...

User comments : 0

More news stories

Adventurous bacteria

To reproduce or to conquer the world? Surprisingly, bacteria also face this problem. Theoretical biophysicists at Ludwig-Maximilians-Universitaet (LMU) in Munich have now shown how these organisms should ...

Revealing camouflaged bacteria

A research team at the Biozentrum of the University of Basel has discovered an protein family that plays a central role in the fight against the bacterial pathogen Salmonella within the cells. The so cal ...

How kids' brain structures grow as memory develops

Our ability to store memories improves during childhood, associated with structural changes in the hippocampus and its connections with prefrontal and parietal cortices. New research from UC Davis is exploring ...

Gate for bacterial toxins found

Prof. Dr. Dr. Klaus Aktories and Dr. Panagiotis Papatheodorou from the Institute of Experimental and Clinical Pharmacology and Toxicology of the University of Freiburg have discovered the receptor responsible ...