Bacteria as factories of the biobased economy

[The SC]

In the nearby future, the raw materials for plastics and fibres that are currently derived from petroleum could be obtained from renewable green resources such as corn straw or wood. The work will be done by bacteria that function as microscopic factories. In his inaugural lecture on 23 March, Richard van Kranenburg, special professor of Bacterial Cell Factories, explained how the bacteria will contribute to the new biobased economy . Prof. Van Kranenburg’s chair is funded by Corbion.

The microworld of bacteria that can function as mini factories is fascinating, says Prof. Van Kranenburg during his inaugural lecture ‘Bacterial cell factories – Applying thermophiles to fuel the biobased economy’ at Wageningen University & Research.
‘Bacteria produce useful products such as lactic acid out of plant sugars. After this microbial process, which we call fermentation, we can purify the resulting products and use them to produce bioplastics and other materials,’ explains the professor. ‘This is an important step in the transition from a fossil economy to an economy based on green chemistry and biotechnology solutions that use renewable raw materials such as corn stover, wheat straw or wood.’
Compost heap
Bacteria are not able to convert these raw materials directly into usable products. The raw material first needs to be pre-treated to release the fermentable sugars. Some bacteria have special enzymes that do this.
‘We found an important bacterium in a compost heap that has such activity. In this warm environment (50 to 60°C), we found a heat tolerant Bacillus species that contains the enzymes needed to release the sugars, allowing the sugars to be used for the fermentation process.’
Industrial fermentation
Fermentation has been used in the production of foods such as bread, wine and soy sauce for thousands of years. Industrial fermentation only arose sometime around 1881 with the production of lactic acid. This process should be improved to further contribute to the biobased economy. For example, most fermentation processes result in byproducts next to the intended products.
‘This is why we are developing a toolkit so that we can genetically modify the bacterium to carry out the industrial fermentation process as efficiently as possible. For example, we could modify it to produce only lactic acid, or a more products with a more complex production pathway, such as succinic acid. One such tool is Cas9. This enzyme can be applied to target and eliminate less productive wild-type bacteria, while ignoring the desired optimized bacteria. These are exciting times for biotechnologists!’ concludes Prof. van Kranenburg.

Source: Wageningen University

 

[The SC]

In July 2015, the Bavarian Ministry of the Environment and Consumer Protection set up the project group “Resource-friendly Biotechnology in Bavaria – BayBiotech.” The aim is to contribute to resource-friendliness through application specific research projects in the field of biotechnology and to support the transition to a sustainable bio-economy. Today scientists at the Technical University of Munich (TUM) and the University of Bayreuth presented the results of their research in Erlangen.

Considering the limited supply of oil and natural gas there is a clear development towards resource friendly and sustainable production of synthetics and intermediate chemical products using biotechnological processes. To this end, the Bavarian Ministry of the Environment and Consumer Protection has initiated the project group “Resource-friendly Biotechnology in Bavaria – BayBiotech.”
“We want to build on our previous successes in environmental protection on the road to a sustainable bio-economy. The project group utilizes biotechnology to advance innovative and environmentally friendly manufacturing processes. With nature’s toolbox we could produce future products using plants and bacteria. Today’s wool sweater might be tomorrow’s car tire made of botanical materials. Our goal is a sustainable bio-economy that combines ecology and economics through the responsible use of biological resources,” says Ulrike Scharf, the Bavarian Minister for the Environment and Consumer Protection, whose Ministry funds the project group to the tune of 2 million euro.

Casing cover made from a blend of Polyhxdroxybutyric acid and polypropylen carbonate. (Image: Andreas Battenberg / TUM)
Bespoke biopolymers
A key focus of the project lies on the biotechnological production of bespoke synthetics made of polyhydroxybutyric acid (PHB). Bacteria produce this biopolymer as a storage substance. PHB has properties like propylene, which is produced from petroleum but is significantly more brittle and thus more difficult to process.
The bacteria always combine the individual building blocks in the same manner. The material thus forms crystalline regions, making it brittle. In the context of the project, teams at the Chair of Chemistry of Biogenic Resources and the Professorship of Biogenic Polymers in Straubing demonstrated how mechanical properties of the biopolymer can be improved by adding other synthetics, such as polylactides.
Separating the production of individual building blocks and the polymerization opens the door to new processing options. Therefore the team led by Thomas Brück, Professor of Industrial Biocatalysis, has developed a resource-friendly production methodology of PHB monomers from bran, a cheap by-product of flour production.
Mixing these monomers with others made from beta-butyrolactone, researchers at the TUM Chairs of Macromolecular Chemistry and Chemistry of Biogenic Resources introduces specific irregularities into the polymer, thereby custom-tailoring the material properties for given applications. The research also develops improved metallic and biogenic catalysts opening the butyrolactone ring.
Biotechnological production of chemical intermediates
Many biotechnological processes make use of spontaneously formed biofilms. However, these are often quite sensitive and therefore cannot be adapted to all desired reactions. That is why teams at the Chairs of Process Biotechnology and Macromolecular Chemistry II of the University of Bayreuth developed artificial biofilms in which microorganisms are embedded into a bespoke synthetic polymer matrix. This makes the bacteria significantly more robust and allows them to be exploited for a wide variety of cases.
Acetic acid bacteria are already being deployed in the production of vitamin C. Since the bacterium must react to myriad environmental stimuli, it has a variety of enzymes on its exterior. Using newly developed biomolecular methodologies, the researchers at the Chair of Microbiology on the TUM Weihenstephan campus and the Institute of Biochemical Engineering in Garching succeeded in removing the unneeded enzymes. The energy of the bacteria is thus concentrated on the biotechnological production of the desired enzymes. This rsults in increased activity and inhibition of undesired secondary reactions.
Compounds that behave in a mirror-like fashion to one another are important building blocks in the synthesis of pharmaceutical products. So-called enoate reductases can accumulate hydrogen at double bonds, thereby producing this property of chirality, as it is called. In this way, for example, carvon, a component of cumin oil, can be converted into the chiral dihydrocarvon. Using various protein engineering techniques, scientists at the TU Munich Institute of Biochemical Engineering have altered the enzyme to increase its activity more than fourfold.

Source: Technical University of Munich