Fermentative production of carboxylic acids from lignocellulose sugars

Our offer

The use of renewable raw materials by fermentative production of metabolic products, for example organic solvents and acids, are objectives defined by the working group “Biotechnological Processes”. The team possesses broadly based bioprocess engineering expertise in the feld of scale-up and process intensification.The processes developed on the laboratory scale in terms of their transferability to an industrially relevant scale are evaluated in the preliminary stages and are optimized repetitively during transfer and scale-up. This includes, for example, the adjustment of process control strategies (batch, fed-batch, continuous) and integrated product purification to reduce the number of process steps or the reutilization of the biocatalysts (e.g. by immobilization on carrier materials).

 

Malic acid made of xylose – fermentation at 1 m³ scale for the first time

Aspergillus oryzae

Microscopic picture of the fungus Aspergillus oryzae.

To date, malic acid has been used primarily in the food and beverage industry. It improves the shelf-life of baked products and provides the sour taste of jams and juices. But it also boasts considerable potential as a building block in the chemical industry. Together with succinic and fumaric acid, it belongs to the group of C4 dicarboxylic acids. C4 acids can be converted into 1,4-butandiol (BDO) – an important precursor for further conversion into a wide variety of chemicals, including plastics, polymers and resins; the possible applications for these chemicals range from golf balls to printing inks and cleaning agents.

Fermentative production of malic acid was developed through the collaboration of the Industrial Biotechnology working group at Fraunhofer IGB and the Biotechnological Processes group at Fraunhofer CBP. Fermentation was carried out with the fungus Aspergillus oryzae, which is designated as a harmless food additive according to the GRAS (generally recognized as safe) status of the US Food and Drug Administration (FDA). In addition to glucose, the strain can also utilize the C5 sugar xylose, which is the main component of hemicellulose and thus can be sourced from wood residues.

Initially, the process was optimized at the laboratory scale; it was then established in stirred reactors and finally successfully scaled up to the 1 m³ scale using the substrate xylose for the first time. Downstream processing could be demonstrated using crystallization. In doing so, several kilograms of malic acid were produced that are now available as a sample for application tests.

High concentrations of xylonic acid through process optimization

xylonic acid

Production of xylonic acid from xylose using Gluconobacter.

Xylonic acid as a replacement for gluconic acid

Gluconic acid is an important constituent of foodstuffs, construction materials and dyes [1]. The acid is produced from glucose, which is obtained from plants rich in starch and thus competes with the production of foodstuffs. An alternative to gluconic acid is xylonic acid: on the one hand, this has similar properties and, on the other hand, it can be obtained from plant components containing lignocellulose or from agricultural waste material. The aim was therefore to develop an efficient process for obtaining xylonic acid from xylose.

250 g/L xylonic acid through optimization

The fermentation-based conversion of xylose is conducted using whole cell catalysis (Gluconobacter sp.), with addition of oxygen as a second reactant. In contrast to competing solutions, fermentation with Gluconobacter sp. has the advantage of being a specific, sustainable and efficient conversion. To date, the team of Industrial Biotechnology Group has achieved a xylonic acid concentration of over 250 g/L through optimization – with a yield of over 90 percent. In the subsequent rudimentary purification process, xylonic acid was obtained at a purity of over 80 percent, which is adequate for technical applications.

Scale-up and sample quantities for application-related investigations

The scalability of the process has already been demonstrated at the Fraunhofer Center for Chemical-Biotechnological Processes CBP by the team in the Biotechnological Processes Group with the 100-liter fermentation, a scale-up to 300 liters is planned. We are already making smaller quantities available for investigations for specific applications. For example, xylonic acid can be tested as a substitute for gluconic acid as a curing retardant for concrete or chelating agent.

Literature

[1] Toivari, M.H., Y. Nygard, M. Penttila, L. Ruohonen, and M.G. Wiebe, Microbial D-xylonate production. Applied Microbiology and Biotechnology, 2012. 96(1): p. 1-8.

Reference projects

FDCAzymes – Lignocellulose based enzymes for the conversion of 5 hydroxymethylfurfural to 2,5 furanedicarboxylic acid

Duration: June 2017 - May 2020

2,5 Furandicarboxylic acid (FDCA) is a biobased alternative to petrochemically produced terephthalic acid, which is used in the production of PET and polyesters for the packaging and textile industries. The FDCAzymes project aims to develop tailor made enzymes for the conversion of 5 hydroxymethylfurfural (HMF) to FDCA, whereby the Fraunhofer CBP will supply the raw material (lignocellulose sugar and HMF) and is partner for process development and scale up.

More Info 

FIP – Fermentative Production of Isobutene

Duration: October 2013 - July 2017

The aim of the project "Fermentative Isobutene Production" is to transfer the process to pre-industrial scale. In the FIP project, a demonstration plant with a nominal capacity of 100 tonnes per year will be designed and constructed and the production process will be scaled up to a fermentation volume of 5000 liters.

More Info 

2GEnzymes – Enzymes for 2G Sugars

Duration: June 2016 - May 2019

The goal of this project is to design an integrated process for the production of second generation sugars using ligninolytic enzymes and novel cellulases. Basis for this is the organosolv process of Fraunhofer CBP, which is already established in pilot scale. The enzyme production will be integrated into the overall sugar production by using fractions originated from the organosolv process as fermentation substrates. The primary feedstock used in this project is beech wood. The overall process will be demonstrated in pilot scale.

More Info 

KomBiChemPro – fine and platform chemicals from wood by combined chemical-biotechnological processes

Duration: November 2015 - May 2018

The aim of the joint project KomBiChemPro is to combine various development activities for the material use of lignocellulose-containing biomass in an integrated biorefinery concept. The most important aspect is the production of marketable products using robust processes and efficient process management in order to ensure broad applicability and competitiveness against petrochemically produced materials and chemicals. On the basis of the work of the partners involved, the subprocesses are combined at one location, mapped in sufficient dimensions and accounted.

More Info 

Bio-Solketal – Synthesis of 100 percent bio-based Solketal (Isopropylidene glycerol)

Duration: September 2014 - June 2017

The focus within this project is the synthesis of 100 percent bio-based Solketal (Isopropylidene glycerol) carried out in a semi-continuous reactor. Solketal can be catalyzed from glycerol and acetone under acidic conditions. This synthesis was developed in a laboratory scale by the GLACONCHEMIE GmbH using biogenic glycerol (purely vegetable, by-product from the biodiesel production).

More Info 

BioQED – Quod Erat Demonstrandum: Large scale demonstration for the bio-based bulk chemicals BDO and IA aiming at cost reduction and improved sustainability

Duration: January 2017 - December 2017

In the EU project Bio-QED, Fraunhofer IGB and its branch institute Fraunhofer CBP are conducting research into fermentative production processes to produce basic chemicals and regarding the scale-up of the processes. The Institute is concentrating in particular on the itaconic acid value chain. In 2017, the Fraunhofer CBP held a demonstration workshop on this topic in which project highlights and results were presented.

More Info 

Integrated Bioproduction – Integrated chemical-biotechnological production of building blocks on the basis of renewable resources in a biorefinery

Duration: May 2009 - April 2012

The objective of the integrated project is to increase the use of renewable resources and, in the long term, to convert chemical production processes for the production of synthesized building blocks to renewable resources. By means of an integrated development along the whole value creation chain from the pilot scale through to production scale the aim is to implement an integrated production on the basis of renewable resources.

More Info 

Innozym  

Duration: April 2009 - March 2012

As highly specific catalysts, enzymes play a central role in industrial biotechnology. They are also in demand for technical applications, for example as sensors and indicators.

More Info