BioQuakes

AP Biology class blog for discussing current research in Biology

Tag: E Coli

Genetic Engineering on Gut Bacteria!?

E. coli on MAC – Photo credit to VeeDunn on flickr under Creative Commons License

Researchers at the Wyss Institute at Harvard University has successfully tested a genetically engineered signaling bacteria within a mouse’s gut. Having known that the many types of bacteria in the human gut can communicate through “quorum sensing” , researchers set to observe a particular type of quorum sensing, acyl-homoserine lactone sensing, which has not been observed in the mammalian gut. They wanted to test if using that particular type of signaling could create a genetically engineered bacterial information transfer system.

Using a strain of E. coli bacteria, they created two different colonies, each with a different genetic change: one was the “signaler”, it contained a copy of the luxl gene which produces a quorum-sensing molecule when activated, and the other was the “responder”, which contained a “cro” gene turning on a “memory element” in the responder.  This “memory element” expressed another copy the the pro gene, which allowed for the loop to continue, and the LacZ gene, which made the bacteria turn blue!

LacZ gene expression – Photo credit to Viraltonic on Wikimedia Commons under Creative Commons License

The researchers analyzed fecal samples of mice given signaler and responder E.coli and they were happy to see the signal transmission, blue coloring, was evident in the samples. This result meant that they had created a functional communication bacteria system in the mouse’s gut.

The researchers then repeated their experiment with a different type of bacteria, S. Typhimurium, as the “signaler” and E. coli as the “responder”, and they were pleased to see similar successful results.  They were able to successfully confirm that is possible to genetically engineer these communication circuits between different species of bacteria in the mammalian gut microbiome.

These tests are merely stepping stones for the bigger goal of creating genetically modified bacteria that will help humans in various different ways: detecting and or curing diseases, improving digestion, and so on. Isn’t it cool that something we barely realize is inside us has such a developed communication system that we might soon be able to cultivate more benefits from? What do you think would be some other benefits to be being able to genetically modify our gut microbiomes?

 

 

Have No Fear, Gut Microbes Are Here!

Ever dream about being a real life Captain America? Well, with the help of microbes, we are one step closer to achieving a “super soldier.” Microbes might not make a soldier muscular, but they can help with soldiers’ health and versatility. Scientist Jeff Tabor is working on engineering a probiotic organism that can help humans easily fight diseases, prevent obesity, and change their body’s ability to adapt to certain environments.

The gut bacteria affects many functions of the human body. The digestive system, immune system, and nervous system are all influenced by gut bacteria. Disrupting these microorganisms can cause indigestion, a weak immune system, depression, insomnia, and affect other cognitive abilities. Tabor’s goal is simply to create a microbe that can be consumed to prevent these problems.

Gut Microbe

Gut Microbe

Initially, Tabor wanted to use these microbes to target obesity because scientists have abundant knowledge of obesity at the molecular level. He recently succeeded in genetically modifying E.Coli to detect chemicals in the body that carry disease in mice guts. He hopes to use this modified E.Coli to sense chemicals in the gut that are connected to obesity and then use other molecules to prevent this obesity. The creation of a microbe that can control weight can be extremely helpful for the U.S. armed forces. For example, soldiers going from sea level to the top of a mountain way above sea level experience changes in temperature and pressure. Using this engineered gut microbe, the soldiers can put on weight to help them keep warm on top of the mountain and then lose weight to keep cool at sea level.

Another military benefit that these microbes can provide is to help soldiers operate effectively on little to no sleep or to help soldiers adapt to changes in their circadian rhythms, either from time change or going below sea level in a submarine. Scientists are interested in experimenting with the gut microbe to be able to achieve these goals in the future.

Some people might be afraid of the possible affects that these genetically modified bacteria might have on the human body. However, Tabor’s goal is for the bacteria to stay in the gut for about six hours to do its job and then self-destruct or die naturally to prevent the bacteria for staying in the body too long. There are other concerning issues about creating a microbe that can help prevent obesity. The creation would take away any incentive for humans to eat healthy and focus on their diets because they could just use the microbe to prevent gaining weight. Any new scientific experiment comes with its pros and cons, but using gut microbes for human health, especially for the military, can be a big step in the right direction.

Source Article

Bringing the Human Gut Microbiome into the Light

The human gut microbiome is an incredible system of symbiotic organisms. These micro-organisms that provide us with vitamins and amino acids as well as break down toxins and protect us from harmful invaders. We could not live without them and they could not survive without their host, us. We carry over 3 pounds of these little helpers in our body and outnumber our cells. Although this system is so important to our survival, it has been hard to study for long periods of time, until now. Judah Folkman, professor of Vascular Biology at Harvard Medical School states, “”Until now, use of traditional culture methods and even more sophisticated organoid cultures have prevented the microbiome from being studied beyond one or two days. With our human gut-on-a-chip, we can not only culture the normal gut microbiome for extended times.”

 Escherichia coli

E. Coli 10000x magnified

https://en.wikipedia.org/wiki/Fecal_bacteriotherapy

The human gut-on-a-chip is constructed from a clear, flexible polymer roughly the size of the a flash drive. This chip simulates the environment of our gut so well that cultures can last up to weeks. This extended period of time can allow for major breakthroughs in the study of the microbiome and what happens when things do not go as planned. Judah Folkman adds, “we can also analyze contributions of pathogens, immune cells, and vascular and lymphatic endothelium, as well as model specific diseases to understand complex pathophysiological responses of the intestinal tract.”

 

The Wyss team thinks that this new technology can help treat patients by eventually culturing there own cells and microbiome on the human gut-on-a-chip to test different treatments. This new technology, although not directly discovering anything about the human gut microbiome, will lead to major discoveries down the line.

 

Main Article:

http://www.sciencedaily.com/releases/2015/12/151214165918.htm

 

Other Articles:

http://www.sciencedaily.com/releases/2014/07/140707103641.htm

http://www.britannica.com/science/human-microbiome

https://en.wikipedia.org/wiki/Human_Microbiome_Project

Bacteria become ‘genomic tape recorders’, recording chemical exposures in their DNA

EscherichiaColi_NIAID

MIT Engineers have developed a way to create genomic tape recorders out of the Bacteria E. Coli. Timothy Lu, an engineering professor at the university describes the method by which they altered the bacterial DNA in order to allow it to store information. The researchers engineered the cells to produce a recombinase enzyme which can insert a certain sequence of Nucleotides into the genome. However, the trait is useful because the enzyme is activated by specific stimuli. In order to retrieve the information the researchers can either sequence the genome and look for the specific code or look for the trait expressed by the targeted gene by using antibiotics. This process will be useful in the future because of its ability to store long term biological memory. Also, this process transcends previous limitations of genome storage as it is now able to indiscriminately store data as opposed to previous methods that were only able to identify a specific stimulus.

Article Link:

http://www.sciencedaily.com/releases/2014/11/141113142006.htm

Useful Links:

http://en.wikipedia.org/wiki/Escherichia_coli

http://en.wikipedia.org/wiki/Whole_genome_sequencing

Image Link:

http://commons.wikimedia.org/wiki/File:EscherichiaColi_NIAID.jpg

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