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Reporting period: 2021-05-01 to 2022-07-31

Our project addressed the under utilization of sugar residual streams from the pulp industry. Plant dry matter, the so called lignocellulosic biomass, is the largest renewable biomass feedstock on Earth. Biorefineries processing such feedstock are projected to make a substantial contribution to a future sustainable economy. By 2030 we have the potential to develop a competitive bio-based European economy producing 30% of our chemicals and 25% of transport fuels, safeguarding millions of jobs. There are numerous lignocellulosic biorefineries in operation today, e.g. sulfite pulp mills in Finland, Norway, Sweden, Austria, Czech, Switzerland, USA and Canada, and several sugar beet biorefineries in UK and Finland. In the last years 5 full scale plants have been put in operation; 1 in Italy, 2 in US and 2 in Brazil. Unfortunately, lignocellulosic biorefineries struggle with low profitability. Such biorefineries have sugar streams that are not converted to higher value chemicals. Some produce low value ethanol (€0.3-0.6 /kg), but most incinerate their sugar to energy use by lack of other alternatives. These companies could therefore be more competitive by adding production of high value products from the sugar platform.
Being able to convert these large amounts of residual sugars (over 14 MT/y in EU alone) will obviously have great economical, and environmental benefits for the society. Instead of using sugars that originate from food, such as corn starch, sugar beet and sugar canes for the fermentation of chemicals, it is desirable to use sugars originating from industrial processes such as the pulp industry, that anyway produce cellulose. It will increase job opportunities, will strengthen the economy, and may help to change the demography of agriculture, from sugars to microbial fermentation to growing food for people.
The overall objective was to utilize these sugar streams that contain inhibitors and complex sugar mixtures that are currently unsuitable for microbial fermentation of high value chemicals, for which we were very successful. In addition, we managed to exploit these sugars and produce high value (>100 USD/kg) compounds that have great benefits in medicine, and are valuable as food and feed additives.
First, we analyzed and studied our complex sugar mixtures originating from the pulp industry, including its content, variability and the presence of inhibitors. We have then designed microbial strains that can tolerate the inhibitors of these sugar residual streams. Moreover, we were also active on modifying the microbial strains and engineer them to produce antimicrobials with high value. Our natural bacteria (the wild type) could not consume 80% of the sugars in the residuals mixtures. Now we have strains that can consume almost 100% of the sugars in the mixture (tested by real industrial sugar streams). We also worked to modify our strains to produce valuable antimicrobials that are not naturally produced by this host. We have managed to develop strains that can produce two different types of antimicrobial and published the results in high quality scientific publications. Because the products our cell factories produce are antimicrobials, compounds that naturally kill microbial cells via membrane damage, we studied the effect of high concentrations of these compounds on the fermentation culture, and modified the cells to be able to tolerate high concentrations, such that the concentrations we can produce will be high. We have now strains that can tolerate the inhibitors and higher concentrations of the antimicrobials than regular (wild type strains) and we in fact managed to produce up to 7 times the state of the art product concentrations in the industry. We also worked on the design of fermentation process that is suitable for these microbial strains: via an advanced digital control system, we can now control the fermentation process in an optimal manner. For this purpose we have designed the model, the controller, an estimator, algorithm based on mathematics and statistics that can correct different measurements during the fermentation process and integrate them in a manner that enables us to achieve optimal control.
To summarize, our main results include
1) strains that consume residual sugar streams (novelty)
2) strains that can tolerate large amount of the residual streams in fermentation
3) strains that produce two types of commercial antimicrobial in very high concentrations (important novelty)
4) New digital fermentation technology that is very effective for antimicobials.
Our strains that we designed can consume and tolerate industrial sugar mixture and produce antimicrobials. This achievement is beyond the state of the art: Currently this industrial mixture is only exploited by strains of yeasts in the production of the low value bioethanol. Our cell factories are efficient in the consumption and conversion of these sugars to high value compounds. Our cell factories convert these industrial sugars to commercial antimicrobials more than 7 times the possible today by the industry!
The potential impact is obvious:
Environmentally, it will promote the full exploitation of sugars that are currently incinerated or used to produce low value compounds. We showed by an LCA studies that our process with our strains reduces at least 70% of the carbon emission compared to the state of the art process to produce the same compounds in the industry. Moreover: today’s processes use glucose-like sugars that originate in food, such as corn starch and sugar canes, while our process exploits industrial sugars byproducts that cannot be consumed by humans or animals.
Economically, the project can contribute to circular economy, because of the exploitation of the residual streams (Figure below). It added a potential value chain to the pulp industry, that has the opportunity to exploit the process and produce high value compounds, adding to their existing processes (production of the low value ethanol). If they choose not to produce themselves, they will be able to sell their sugars (that are not currently sold) to companies that are interested in our advance and effective fermentation process that relies on these sugars. The project (our strains + our technology) interconnected companies that are traditionally not have mutual commercial interest, to create at least two novel value chains: Pulp industry to medicine, pulp industry to food and feed industries.
For the European society and jobs creation: Because we also developed digital technologies in addition to biotechnology (we actually integrate the two fields), we created a process that we can exploit by later upscaling and developing a demo plant (planned for 2023). This will enable the European fine chemical industry to compete with the low-cost production of antimicrobials and other high value compounds (e.g. vitamins, food additives and cosmetics) in China and other countries in the far-east. It will enable them to produce larger quantities of better quality products that will be manufactured in Europe. With other words, we expect our high efficient technology that enables the production of high quality compounds to outcompete the low-cost labor that is possible in the far-east, therefore creating high skilled jobs in the EU and export of high quality products.