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January 23, 2017 / 25 Tevet, 5777

Posts Tagged ‘scientists’

Weizmann Scientists Engineer Bacteria Making Sugar from Greenhouse Gas

Tuesday, June 28th, 2016

All life on the planet relies, in one way or another, on a process called carbon fixation: the ability of plants, algae and certain bacteria to “pump” carbon dioxide (CO2) from the environment, add solar or other energy and turn it into the sugars that are the required starting point needed for life processes, reads a press release of the Weizman Institute headlined, “Eating Air, Making Fuel — Weizmann Institute scientists engineer bacteria to create sugar from the greenhouse gas carbon dioxide.”

At the top of the food chain are different organisms, such as humans, that use the opposite means of survival: they eat sugars (made by photosynthetic plants and microorganisms) and then release carbon dioxide into the atmosphere. This means of growth is called “heterotrophism.”

Is it possible to “reprogram” an organism that is found higher in the food chain, which consumes sugar and releases carbon dioxide, so that it will consume carbon dioxide from the environment and produce the sugars it needs to build its body mass? That is just what a group of Weizmann Institute of Science researchers recently did.

Dr. Niv Antonovsky, who led this research in Prof. Ron Milo’s lab at the Institute’s Plant and Environmental Sciences Department, says that the ability to improve carbon fixation is crucial for our ability to cope with future challenges, such as the need to supply food to a growing population on shrinking land resources while using less fossil fuel.

The Institute scientists rose to this challenge by inserting the metabolic pathway for carbon fixation and sugar production (the so called Calvin cycle) into the bacterium E. coli, a known “consumer” organism that eats sugar and releases carbon dioxide.

The metabolic pathway for carbon fixation is well known, and Milo and his group expected that, with proper planning, they would be able to attach the genes containing the information for building it into the bacterium’s genome. Yet the main enzyme used in plants to fix carbon, RuBisCO, utilizes as a substrate for the CO2 fixation reaction a metabolite which is toxic for the bacterial cells. Thus the design had to include precisely regulating the expression levels of the various genes across this multistep pathway.

In one way the team’s well-thought-out plan was a resounding success: The bacteria did indeed produce the carbon fixation enzymes, and these were functional. But the machinery, as a whole, did not “deliver the goods.” Even though the carbon fixation machinery was expressed, the bacteria failed to use CO2 for sugar synthesis, relying instead on an external supply of sugar. “Of course, we were dealing with an organism that has evolved over millions of years to eat sugar, not CO2,” says Antonovsky. “So we turned to evolution to help us create the system we intended.”

Antonovsky, Milo and the team, including Shmuel Gleizer, Arren Bar-Even, Yehudit Zohar, Elad Herz and others, next designed tanks called “chemostats,” in which they grew the bacteria, gradually nudging them into developing an appetite for CO2. Initially, along with ample bubbles of CO2, the bacteria in the tanks were offered a large amount of pyruvate, which is an energy source, as well as barely enough sugar to survive. Thus, by changing the conditions of their environment and stressing them, the scientists forced the bacteria to learn, by adaptation and development, to use the more abundant material in their environment. A month went by, and things remained fairly static. The bacteria seemed to not “get the hint.” But in a month and a half or so, some bacteria showed signs of doing more than “just surviving.” By the third month the scientists were able to wean the evolved bacteria from the sugar and raise them on CO2 and pyruvate alone. Isotope labeling of the carbon dioxide molecules revealed that the bacteria were indeed using CO2 to create a significant portion of their body mass, including all the sugars needed to make the cell.

When the scientists sequenced the genomes of the evolved bacteria, they found many changes scattered throughout the bacterial chromosomes. “They were completely different from what we had predicted,” says Milo. “It took us two years of hard work to understand which of these are essential and to unravel the ‘logic’ involved in their evolution.” Repeating the experiment (and again waiting months) gave the scientists essential clues for identifying the mutations necessary for changing the E. coli diet from one based on sugar to one using carbon dioxide.

Prof. Milo noted that “the ability to program or reengineer E. coli to fix carbon could give researchers a new toolbox for studying and improving this basic process.”

Although currently the bacteria release CO2 back into the atmosphere, the team envisions that in the future their insights might be applied to creating microorganisms that soak up atmospheric CO2 and convert it into stored energy or to achieving crops with carbon fixing pathways, resulting in higher yields and better adaption to feeding humanity.


Man-Made Meat? A fence for Wisdom is Silence

Tuesday, August 13th, 2013

After years of research and development, a man-made hamburger was publicly tasted for the first time last week. The burger was not animal flesh, instead it was grown in a laboratory. However, it was grown in a way that mimics the way animals grow their own flesh. Thus, it was pretty close to dead animal meat in flavor and texture.

This incredible scientific breakthrough prompted a plethora of questions. For the religious community with rituals and laws attached to the eating of meat even more questions were asked.

It seemed that one could hardly browse the Internet for five seconds without seeing a juicy soundbite (sorry, couldn’t resist) about whether the meat was kosher or whether is was meat at all. Chabad’s website had one approach. OU had another approach. Reuters had a third opinion in their article. NBC added another view.

I must have been asked by a dozen people what to make of the man-made meat mystery.

This is what I think. No one has any idea what they are talking about. Non-scientists have no chance of understanding the precise manner in which this meat was manufactured. I have tried to understand how it all works and it is almost impossible to find the full technical explanation with all the requisite background information. A very smart scientists tried explaining it to me, but even after I got the gist of the process I had more questions about stem cells and other background than I had before he explained it to me. I am pretty confident that Chabad, OU, the Reuters people, and even NBC News reporters don’t have a clue how this meat is made.

Sure, they  say “don’t rely on this for halacha” or something to that effect, but that makes things even worse. Why offer a meaningless opinion that is based on ignorance? It seems to make a mockery of Jewish law. But Jewish law is very serious and serious people will offer serious opinions on this matter. The proper response for almost the entire population of planet Earth to these eternal questions about man-made meat is “I am not qualified to render an opinion on this matter.”

Without a thorough understanding of how the meat is made, any discussion of the halachic ramifications of the meat is not even conjecture. It is pure fantasy. Further, deciding the halachic status of this issue will require a breadth of Torah knowledge that is possessed by a mere handful of people on the planet. You can’t pasken this shyla with Yad Moshe, Google, or the Otzar. This is a brand new question of Jewish law and will need serious investigation into the science and the various tenuously analogous precedents in Jewish law. The Torah does not discuss synthetic meat. And even if it did, who says this meat would be the same as the synthetic meat found in Jewish law?

The only way this question can be seriously answered is with a conference of scientists and rabbis who fit the descriptions above. Scientists who can thoroughly explain how the meat is made and Torah scholars who know kol haTorah kula will need to decide this issue. Anyone else jumping into the discussion is wielding a knife in a nuclear war. It’s that useless.

If I can, I will try to attain a scientific understanding of how this meat is produced and then perhaps I will be qualified to even ask the question to my (qualified) posek. But until such time, I wouldn’t dare wade into this very, very deep pool. I think this is the proper policy under the circumstances. We sound more educated and cutting edge when we admit what we don’t know as opposed to when we pretend we know what we are discussing.

Visit Fink or Swim.

Rabbi Eliyahu Fink

Printed from: http://www.jewishpress.com/blogs/fink-or-swim/man-made-meat-a-fence-for-wisdom-is-silence/2013/08/13/

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