Engineered bacteria can make the ultimate sacrifice

Nov 20, 2012
Engineered bacteria can make the ultimate sacrifice
Engineered bacteria can be used to demonstrate the conditions where programmed cell death becomes a distinct advantage for the survival of the bacterial population. Credit: European Molecular Biology Organization

Scientists have engineered bacteria that are capable of sacrificing themselves for the good of the bacterial population. These altruistically inclined bacteria, which are described online in the journal Molecular Systems Biology, can be used to demonstrate the conditions where programmed cell death becomes a distinct advantage for the survival of the bacterial population.

"We have used a synthetic biology approach to explicitly measure and test the adaptive advantage of programmed bacterial in ," said Lingchong You, senior author of the study and an associate professor at the Department of Biomedical Engineering, Duke University, and the Duke Institute for & Policy. "The system is tunable which means that the extent of altruistic death in the can be increased. We are therefore able to control the extent of programmed cell death as well as test the benefits of altruistic death under different conditions." The lead author of the study is Yu Tanouchi, a graduate student in the Department of . Anand Pai and Nicolas Buchler also contributed to the work.

Scientists have known for some time that programmed cell death can be linked to the response of bacteria to stressful conditions, for example starvation of amino acids or the presence of competitor molecules. However, it is not clear why cells should choose to die under such conditions since it gives them no immediate advantages. Some researchers have suggested that programmed cell death allows cells to provide benefits to their survivors but until now it has been difficult to test this directly in experiments.

The researchers used synthetic biology procedures to engineer Escherichia coli in such a way that the bacterial cells are capable of suicidal behavior and promoting the good of the bacterial population. To do so they introduced a gene circuit, which consists of two modules, into the bacteria. If the "suicide module" is active it leads to the rupture and death of some bacterial cells when they are challenged with the antibiotic 6-aminopenicillanic acid. If the "public good" module is expressed, a modified form of the enzyme beta-lactamase is produced, which protects surviving cells from rupture or lysis by breaking down the antibiotic. This protection only occurs when the enzyme is released from inside the that make the ultimate sacrifice and die after rupture.

"Our results clearly demonstrate that it is possible to have conditions where the death of some bacteria confers an advantage for the overall population of bacteria," remarked You. "The optimal death rate for the bacterial population emerges after sufficient time has passed and is clearly visible in our system."

The scientists were also able to provide a possible explanation for the "Eagle effect", an unexpected phenomenon where appear to grow better when treated with higher antibiotic concentrations. "Overall our results fill in a conceptual gap in understanding the evolutionary dynamics of programmed bacterial death during stress and have implications for designing intervention strategies for effective treatment of bacterial infections with antibiotics," concluded You.

Explore further: Better mouse model enables colon cancer research

More information: doi: 10.1038/msb.2012.50

Related Stories

Antibiotic resistance spreads rapidly between bacteria

Apr 11, 2011

The part of bacterial DNA that often carries antibiotic resistance is a master at moving between different types of bacteria and adapting to widely differing bacterial species, shows a study made by a research ...

Recommended for you

First step towards global attack on potato blight

1 hour ago

European researchers and companies concerned with the potato disease phytophthora will work more closely with parties in other parts of the world. The first move was made during the biennial meeting of the ...

Bacteria study could have agricultural impact

2 hours ago

Wichita State University microbiology professor Mark Schneegurt and ornithology professor Chris Rogers have discovered that one of North America's most common migratory birds – the Dark-eyed Junco – carries ...

Sex chromosomes—why the Y genes matter

14 hours ago

Several genes have been lost from the Y chromosome in humans and other mammals, according to research published in the open access journal Genome Biology. The study shows that essential Y genes are rescue ...

Better mouse model enables colon cancer research

May 27, 2015

Every day, it seems, someone in some lab is "curing cancer." Well, it's easy to kill cancer cells in a lab, but in a human, it's a lot more complicated, which is why nearly all cancer drugs fail clinical ...

How to get high-quality RNA from chemically complex plants

May 26, 2015

Ask any molecular plant biologist about RNA extractions and you might just open up the floodgates to the woes of troubleshooting. RNA extraction is a notoriously tricky and sensitive lab procedure. New protocols out of the ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.