Precision microbe, innovative iron-enabler in fertiliser

Kamnik, Slovenia — On March 30, 2023, leading precision fermentation developer and SUSFERT partner, Acies Bio, hosted an inauguration event for its new fermenter that was co-funded by the H2020/BBI-JU (now called the CBE JU).

The joint public/private investment into the 6.5 cubic metre fermenter increased Acies Bio’s bio-process capacity to efficiently scale-up and produce siderophore during the initial commercial production stage of the project. The fermenter also will allow the company to scale, demonstrate, and produce products for bio-based agriculture and food chains.

Acies Bio is a microbial bio-technology development leader situated close to Ljubljana in Slovenia. It is one of the few companies that can offer complete technology development from the idea concept to the development of a commercial production process.

Innovative iron-transport using siderophore

Iron is an essential element for plant growth, but its low bioavailability in soil can limit crop yields. Siderophore molecules, produced by certain micro-organisms, have a high affinity for iron, allowing them to bind to it and make it more accessible to plants. The process, called chelation, contributes to sustainable agriculture by reducing the need for synthetic iron supplements.

SUSFERT’s nine prototype fertilisers, currently under evaluation for possible agricultural use, were showcased and explained at the event. The fermented siderophore is being used as a liquid prototype fertiliser that is being tested in field trials.

The prototype fertilisers (above) are known as SUSKIT. They are displayed in plastic-free bottles which are biodegradable, and are produced by Naku, Austria. The fermented siderophore is the orange liquid in the bottle below.

Current iron-chelation EDTA toxic to environment

Currently, the most widely used chelator in agriculture is Ethylenediaminetetraacetic acid (EDTA) which is made in a chemical process from fossil sources that uses toxic chemicals for its production. Furthermore, EDTA is not biodegradable, and it can bind and solubilise heavy metals when released into nature causing environmental and health issues.

ARIC identifies micro-organism for sustainable iron transport

SUSFERT partner, Agrana Research & Innovation Center (ARIC), developed the fermentation protocol by settling on the use of siderophore rhodotorulic acid for the project using Rhodotorula mucilaginosa as the micro-organism.

Additionally, a by-product from glucose crystallization in AGRANA corn starch production was used as an affordable substrate. Read below how ARIC identified the right migro-organism and how the fermentation protocol was established.

Acies Bio was given the ARIC siderophore fermentation protocol and developed it into a production protocol that upscaled the fermentation process in a simple process that is similar to the brewing of beer.

The process does not use fossil sources for production, and the siderophore is fully biodegradable, eliminating the major problems that come with the usage of current traditional chelators such as EDTA.

Acies Bio CEO inaugurates sustainable fermenter

The fermenter demonstration event was opened by Acies Bio CEO, Dr Stefan Fujs, with the ribbon-cutting ceremony watched on by the Mayor of Kamnik, Mr. Matej Slapar.

Also present were a number of industrial representatives and government bodies, including from the Ministry of the Economy, Tourism and Sport and Spirit Slovenia Public Agency, as well as SUSFERT partners from RTDS Group, AGRANA and ARIC. The participants were given a tour of the Acies Bio facility with a live fermentation of the project’s siderophore.

Mr Štefan Fujs said the additional 6,500 litre fermenter was complementary to the company’s expansion of its SmartRoute services. He said that with the upgrade the company was now able to scale, demonstrate and produce different products within AgBio, but also in other industries, such as food and sustainable biochemical production.

Another important upgrade we did is in the downstream processing – the upgrade there enables us to efficiently extract and formulate final products, such as liquid iron fertiliser in the case of SUSFERT,” CEO of Acies Bio, Mr Štefan Fujs said.

“Acies Bio is developing micro-biotechnology solutions to mitigate the negative impact on our environment and thereby create a healthier future for all of us,” he concluded.

The successful collaboration of partners on consortia accelerate the development and deployment of novel, sustainable solutions that address global challenges.

Sustainable solutions enabled by EU funding collaboration

SUSFERT Project Manager, Mikael Muegge, presented SUSFERT and demonstrated the protype fertilisers that are being tested currently, including the project’s Nutrigels. He said that the stakeholder event underscored the critical role of the CBE which is one of the largest public-private partnerships that drives bio-based innovation for the bio-economy.

“This event highlights the achievements that are made possible with the engagement of research, industry, and the CBE.

“Through the contribution of financial resources within the SUSFERT project we have managed not only to develop and upscale innovative iron chelating bio-based solutions as liquid fertilisers, but also construct a bioreactor (fermenter) that will enable further solutions to be developed and upscaled for the bio-economy beyond the project,” Muegge said.

As the world population grows, the demand for food production increases. This places immense pressure on agriculture to produce more food in a sustainable way, while using fewer resources and causing less harm to the environment.

Investing in European biotechnology capabilities to increase the downstream capacity of innovative, safe, and environmentally friendly products, like SUSFERT siderophore, has the potential to transform the agricultural industry.

Enabling fast-growing SMEs like Acies Bio to contribute to the European bio-economy by creating jobs and sustainable products is part of the success story of European funding. The company now can ferment siderophore batches to large-scale requirements.

The SUSFERT key exploitable result rested on good collaboration and the essential transfer of knowledge between the three partners — Austrian fruit, starch, and sugar industry giant AGRANA, its research centre ARIC, and the rapidly-growing SME, Acies Bio.

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Magic of Siderophore by ARIC

The word ‘Siderophore’ comes from Greek meaning “iron carrier”. Siderophores are naturally derived chelates which catch iron-ions from the soil and make them available for plants. Especially in Mediterranean countries, where there is a high lime content in the soil, iron-ions are precipitated and cannot be absorbed by the crops. Siderophores counteract this and prevent iron-ions from precipitation, and maintain the plant´s iron supply.

Aric’s discovery for SUSFERT

SUSFERT partner and biochemistry scientist from ARIC, Dr Markus Omann, (pictured below) said that the initial work at the research centre was focused on fermenting siderophores with the filamentous fungus Neurospora crassa  which was known to produce siderophores.

“When I started at ARIC, I assumed the responsibility of creating a suitable siderophore for the project. I noticed that the yield was very low for the Neurospora crassa fungus, and not sufficient for any application.

Because of this, we decided to search for another siderophore producing micro-organism which we finally found in the yeast Rhodotorula mucilaginosa. With this organism we were able to do a very good job in the fermentation optimization.

One crucial step was the preparation of the inoculum, which is always the secret of a good fermentation. For medium cost savings, we started to use different by-products from AGRANA Starch’s production processes. We could identify a side stream of the glucose crystallization from corn starch as a valuable carbon source.

Additionally, we found out that the ammonia we used for the pH setting was sufficient as a nitrogen source. With a proper adjustment of the oxygen saturation and rotor speed, we succeeded in increasing the siderophore yield from milligrams into more than 10 grams/litre.

The fermentation protocol and the production strain Rhodotorula mucilaginosa was subsequently handed over to AciesBio within the SUSFERT project,” Omann told SUSFERT communication.

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Philippa Webb-Muegge, Martin Kavšček and Ben Leitner contributed to this article.