Dr. Weizmann's bacteria strikes a second time

Dr. Chaim Weizman would surely have been satisfied with the news that the bacterium that played an important role in his efforts for the establishment of the State of Israel, may have another international achievement to his credit 

 
 
From the right: Dr. Yoav Barak, Dr. Eli Morg, Hadas Gilery, Alon Karpol, Ilit Noah, Rachel Chaimovitz, Yonatan Caspi and Prof. Ed Bayer. From paper to sugar
It is possible that the bacterium that contributed greatly to the realization of the Zionist vision will return and also contribute to the realization of the vision of recycling high-cellulose waste. Dr. Haim Weizman would surely have been filled with satisfaction at the news that the bacterium that played an important role in his efforts for the establishment of the State of Israel, may have another international achievement to his credit.

As a promising young scientist in the field of organic chemistry, in Manchester, before World War I, Weizmann discovered a bacterium that produces acetone and butyl alcohol. Although one senior professor at the university advised him to "pour that stuff down the sink", Weizmann continued to investigate the bacteria. The continuation is recorded in the Book of Chronicles. When the war broke out, there was a severe shortage of acetone, which was essential for the production of gunpowder. Acetone was then mainly produced from wood, but due to the lack of these raw materials, the importance of Dr. Weizmann's bacteria, which was able to produce acetone from corn, increased.

At the request of the British government, Weizmann produced, using the bacterium, significant quantities of the vital substance. This achievement raised his prestige, and helped him achieve the historic Balfour Declaration from 1917, which promised the establishment of a national home for Jews in the Land of Israel.

These days, the bacterium, called Clostridium acetobutylicum, is returning to the forefront of science. Prof. Edward ("Eddie") Bayer, from the Department of Biological Chemistry at the Weizmann Institute of Science, found a way to use Dr. Weizmann's bacteria to reduce environmental pollution and produce substances at the same time. It is about recruiting the bacteria to break down cellulose, which is the main component of plant cell walls.

Cellulose is a stable chain of sugar molecules, which gives wood its strength and serves as an important component in essential products such as cloth and paper. A chain of more than seven sugar units already creates an insoluble substance, but cellulose may contain up to 10,000 sugar units, making it an especially powerful substance. In nature, cellulose fibers of trees and other plants are broken down by various microorganisms, in soil and water. To perform this complex job, those microorganisms use a kind of molecular machine consisting of a kind of "crankshaft" carrying several enzymes. This machine, the cellulosome, breaks the tough and insoluble cellulose, and cuts it into units of soluble sugars that return to the biochemical activity cycle of the plant cells. The problem is that the natural cellulose has a very hard time breaking down the cellulose found in man-made products, such as paper. As a result, billions of tons of non-degradable paper accumulate in waste sites, creating a global environmental problem of enormous proportions.

Prof. Edward ("Eddie") Bayer, from the Department of Biological Chemistry at the Weizmann Institute of Science, and Prof. Raphael Lemmed from Tel Aviv University, who discovered the cellulosome in 1983, and in the years that followed clarified its structure, are now building cellulosomes "to order", which can perform many different operations, including efficient paper shredding. These "initiative" cellulosomes can act independently, or as part of different microorganisms. To change and improve the efficiency of the cellulosomes, the scientists use methods of genetic engineering, which allow them to add, subtract and redesign different subunits included in the cellulosome machine. In this way, the scientists created hundreds of types of cellulosomes, one of which, found to be the most effective, is based on a combination of three enzymes. This cellulose contains enzymes that work according to two complementary methods. One enzyme cuts the cell when it traps it in an opening in its structure, like a kind of "Pacman". The second enzyme interrupts the molecular chain of the cell when it passes it through a channel found in its structure.

The use of this engineered cellulose is still far from being applied in waste treatment, but in the laboratory we can already see the buds of success: the artificial cellulose manages to turn shredded paper into a paste of soluble disaccharides, within one day. "Nature does not overcome paper on its own. Therefore, we aim to create cellulose that will perform actions that were not expected, and were not required by evolution," says Prof. Bayer.

Many scientists, in different parts of the world, are working to develop ways to improve the function of the cellulosome in different microorganisms. This course of action brought Dr. Weizmann's bacterium back to center stage. With the decoding and mapping of its genome it became clear that Clostridium acetobutylicum

 There are genes for cellulose. But just like junk that has been forgotten in the cellar for many years, this cellulose is inactive, so the bacterium does not use it. Following Prof. Bayer's research and findings, French scientists began using methods of genetic engineering, with the aim of reactivating the cellulosome of Dr. Weizmann's bacterium, and making it produce acetone and butyl alcohol from waste paper, and not from corn, as was done during the years of the First World War. It seems that the bacteria that greatly contributed to the realization of the Zionist vision, will return and also contribute to the realization of the vision of recycling high-cellulose waste.

 
 
 
The structure of the cellulosome