• Sweet Blood in the Middle Kingdom

    Treating the Widespread Condition Diabetes in Asia with Acarbose

    show caption

    Sugar jam: body cells usually absorb glucose (top globes in the graphic) after the pancreas has released the signal hormone insulin (globes below). In patients with type 2 diabetes, this mechanism only functions inadequately and the harmful glucose accumulates.

Diabetes is on the increase all over the world, but China has been hit hardest. The pharmaceutical compound acarbose helps Asian diabetes patients manage their blood glucose levels. Bayer’s Active Ingredient Production is now optimizing the bacteria that produce the substance using cutting-edge molecular biology technologies.

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  • The Challenge:
    Type 2 diabetes is on the increase all over the world, especially in Asia where more and more people are now affected. The medical need for acarbose, an active ingredient produced by bacteria, is increasing.
  • Solution:
    New molecular biology methods can be used to selectively optimize the bacteria strains that produce the active substance.
  • Benefit:
    Using optimized microbes can help to make acarbose production even more efficient.

The Far East is gradually moving closer to the western world, and not least in terms of lifestyle and daily food. In China, burgers and chicken wings are increasingly common dishes on the menu. “The growing economy and modernization in this country has led to changed lifestyles as well,” says Xiaoqing Li, medical affairs manager at Bayer in China. “Over the past decades, the level of obesity in the population has increased sharply, while physical exercise has declined.”

Obesity Is a Growing Problem in China

The economic developments are related to higher incidences of some diseases in China, above all diabetes mellitus. Almost one-tenth of the Chinese population is now affected by this condition; in 1994, the figure was just 2.5 percent. “Diabetes mellitus (type 2 diabetes) is on the rise in China, and affecting not only elderly people but now also children,” says Li. What’s more, only one in three affected people are aware that they have the disorder.

Worldwide, some

415 million

are affected by diabetes today – by 2040, that figure could be 642 million.

Diabetes is actually a condition that, depending on which stage it is at, responds well to treatment. As a result, the demand for antidiabetic medications is increasing in China. One Bayer antidiabetic product with the active ingredient acarbose is manufactured in Wuppertal, the site where Bayer was founded. Approximately 80 percent of the produced substance is exported to China. “Acarbose is produced biotechnologically by the Actinoplanes bacterium,” explains Till Zemke, plant manager for acarbose active ingredient production at Bayer in Wuppertal. In view of the huge demand, ­Bayer researchers have been working steadily for more than 20 years to improve the manufacturing conditions for acarbose. In recent years, cutting-edge technologies have made it possible for researchers to scrutinize the strains of Actinoplanes bacteria that are used in the production of acarbose in great detail.

Overweight Asians: Chinese boys exercise in order to lose excess weight.

Diabetes mellitus (type 2 diabetes) is on the rise in China, and affecting not only elderly people but now also children

In the body, acarbose delays the production of monosaccharides, notably glucose, by inhibiting specific enzymes on the brush-border membrane of the small intestine, which are responsible for the digestion of complex polysaccharides and sucrose. In this way, acarbose can significantly reduce rising glucose levels after a meal.

More Food for Bacteria Thanks to Acarbose

The active ingredient is useful not only to diabetes patients. In nature, acarbose secures the supply of nutrients for Actinoplanes. This species of bacteria produces acarbose and excretes it into the environment, where the compound prevents polysaccharides from being used by competing bacteria by inhibiting their production of polysaccharide-cleaving enzymes, rendering this source of food useless to them. Actinoplanes by contrast has full access to these nutrients as it produces its own polysaccharide-degrading enzymes which are not inhibited by acarbose. In this way, Actinoplanes wins the battle for nutrient sources against competing bacteria.

In healthy people, when the small monosaccharides pass into the bloodstream, the hormone insulin allows other body cells to absorb glucose from the bloodstream and use it as a source of energy. In patients with type 2 diabetes, their body cells develop a form of resistance to insulin, which leaves the cells unable to absorb glucose from the blood normally. The sweet blood containing high levels of glucose can cause major damage to the body: elevated blood glucose levels have a negative effect on the blood vessels in the long term. Particularly affected are the fine capillaries in the eyes and kidneys. The consequences are damage to the retina, kidney failure, ulcers or stroke.

92.4 million

adults in China suffer from diabetes.

In type 2 diabetes patients, acarbose inhibits specific digestive enzymes of the small intestine and delays glucose release from complex carbohydrates and thus reduces rising glucose levels after a meal significantly.

New Tools to Optimize Bacteria

With the increasing demand for acarbose in Asia, Bayer scientists are now planning to make targeted modifications to the genome of the bacterium in order to make acarbose production more efficient while at the same time further optimizing the quality of the manufactured acarbose.

“Technical developments have made possible completely new approaches, allowing us to refine even established processes,” says Dr. Winfried Rosen, plant manager for acarbose active ingredient production in Wuppertal. The scientists created a kind of roadmap of the Actinoplanes bacterium genome, with all known genes and their properties. It shows where each gene lies and how the DNA of each strain, including those used in the past, differs from the others.

“For this task, we got help in the shape of the specialists from the Center for Biotechnology – CeBiTec for short – at the University of Bielefeld,” says Zemke. “The experts there are engaged in cutting-edge research into bioinformatics and genome sequencing.” Professor Alfred Pühler and his “Genome research of industrial microorganisms” workgroup at CeBiTec sequenced the entire genome of the various strains of Actinoplanes. “We were also able to analyze which genes are particularly active and which proteins and metabolic products are produced by the bacteria,” explains Pühler. The researchers were particularly interested in the metabolic pathways that are involved in the production of acarbose. For example, they compared how the gene activity varied with different sources of nutrients or during different growth phases. Their work generated a wealth of knowledge. “We can now use these findings to make targeted changes to the current production strain as needed,” says Pühler.

Till Zemke in Bayer’s acarbose production facility in Wuppertal.
Bacteria produce the natural substance in huge fermenters, watched by Bayer employee Thomas Kiesl.

A Regulator Gene Promises Increased AI Production

His team and their colleagues at Bayer are planning to modify a regulator gene, for example. “It influences the DNA region that is responsible for acarbose synthesis,” says Pühler. If the researchers manage to modify this regulator in such a way that it increases activity in this acarbose DNA region, the bacterium could produce more active substance. Another objective could be to suppress the production of secondary components which otherwise have to be removed by means of complex purification stages.

When Sugar Becomes Dangerous

When we eat a bowl of spaghetti, polysaccharides reach our intestines which are then broken down by enzymes into monosaccharides, e.g. glucose. These monosaccharides are transported via the bloodstream into the body cells. This process is made possible by the messenger substance insulin. The problem in diabetes patients is that they either produce too little insulin or none at all (type 1 diabetics), or produce enough of the hormone but the target cells no longer react to the signal (type 2 diabetes). In both cases, the body cells are unable to absorb sufficient glucose. As a result, their blood glucose levels shoot up after food intake. In the long term, this causes damage to the blood vessels and nerves. In the worst case, it can lead to heart attacks, strokes and kidney damage, or even to blindness and amputation of the feet and legs. If the metabolic disorder is diagnosed at an early stage and treated correctly, patients can manage their blood glucose levels pharmacologically and avoid serious complications.

Technical developments allow us to refine even established processes.

In theory, these kinds of improvements can be relatively simply planned using gene maps. But in reality, the processes and interrelationships in the bacterial cells are significantly more complicated. “It’s not ever likely to be just a switch that we have to flip. Much more probable is that we have to combine lots of switches to achieve our objective,” explains Zemke.

Bayer Researchers Have Spent 20 Years Optimizing the Strain

Targeted modification of specific genes is not possible without the genome map. In the past, Bayer researchers would deploy chemicals or ultraviolet radiation to create random mutations in the genetic material of Actinoplanes, and then run tests to find out if any of these changes increased the acarbose yield. “These analyses were tremendously time-consuming. We had to pick out from among thousands of bacteria the few ones that grew well and produced lots of acarbose,” remembers Zemke.

For More Efficient Microbes

Big helpers can be tiny: Bayer researchers have been using the Actinoplanes bacterial strain to produce the natural substance acarbose since 1967. Over the past decades, they have continuously optimized the strain through random mutations and judicious selection of strains with beneficial gene variations. Thanks to state-of-the-art molecular biology – omics technologies – the scientists are now able to make targeted improvements to the microbes. For example, the researchers use genomics to read all of the genes in a bacterial strain and then compare the production microbes with their standard siblings. This method allows them to locate genes that are associated with greater biosynthesis activity. Using transcriptomics and proteomics, they can analyze which genes are read – i.e. used – by the bacterium. The scientists can take a snapshot of the cell condition by carrying out metabolomics testing to determine all of its metabolites. By modifying the identified genes, for example, they can create high-performance bacteria carrying the gene for elevated productivity and thus increase the efficiency of acarbose production.

More than

3,000 tons

of acarbose have been produced at Bayer’s Wuppertal site and exported to various parts of the world since the product was launched. (Source: Bayer)

Bayer’s experts have already repeatedly enhanced the performance of the little active substance producers over the past 20 years using this painstaking technique. By comparison, while the original strain of Actinoplanes bacteria produced less than 0.5 grams of acarbose per liter of culture medium, the strain used at present produces approximately 80 times as much. “Using new technologies and thanks to our cooperation partners at CeBiTec, we now also understand the changes that we randomly created in the past,” says Zemke, underlining the potential of genomics and bioinformatics. “We can trace the managed evolution from the original strain right through to the one currently used in production and draw new conclusions from it again.” In this way, the researchers were able to characterize and file for patenting some 2,000 such mutations in the genome of Actinoplanes which led to its enhanced performance.

And CeBiTec and Bayer are already preparing the next technological step, which will involve genome editing. Today, new methods in molecular biology can be used to selectively modify DNA in the genome, almost like molecular scissors which enable scientists to cut out and replace genes. “We have adapted genome editing to Actinoplanes,” reports Pühler. “We are now able to genetically modify each individual gene in the organism selectively.” The scientists at Bayer and CeBiTec are working together in this project to make Actinoplanes an even more effective active ingredient producer, so that diabetes patients in Asia and all over the world can continue to rely on their therapy.

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