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Fungal Production Systems Utilizing pectin-rich agricultural Residues

Funded by the German Federal Ministry of Education and Research (BMBF), our goal is to find new solutions for the supply of bio-based chemicals from renewable resources. To this end, we combine the expertise of our consortium members from the fields of biotechnology and bioprocess engineering. By focusing on agricultural residue streams from fruit and vegetable processing, we avoid competition for feedstocks that could also be used as food. At the same time, we are adding an innovative, value-added step to the existing cascading use of these resources.

The agricultural residues we use are particularly rich in pectin and hemicellulose, making them an ideal basis for a variety of chemical substances that can be obtained from the most abundant sugars, such as D-galacturonic acid and arabinose. These find application, for example, in the food or cosmetics industry and beyond.

PRO SUPER: Fungal fermentation of pentose sugars from hemicellulose for the production of xylitol

Building on the previous project "PRO-SUGAR", in which D-galacturonic acid was made available from the pectin fraction of apple pomace and sugar beet pulp and transformed into polyhydroxy acids, the follow-up project "PRO-SUPER" deals with another sugar building block for the complete utilization of these residues. Enzymatic degradation of hemicellulose in plant cell walls in addition to pectin can release pentose sugars, such as arabinose and xylose, as further feedstocks for fungal bioconversion. The released pentoses are then to be converted to xylitol, which is used, for example, as a sweetener. The sugar alcohol has almost the same sweetening power as sucrose, but only a fraction of the calories. Xylitol is also valued for the prevention of caries and has a lower glycemic index than sucrose. The industrial production of xylitol is currently based on a cost- and energy-intensive chemical catalysis. The goal in the "PRO-SUPER" project is to develop a more ecologically and economically resource-efficient option.

Sacharomyces cerevisiae fermentation of galacturonic acid to L-ascorbic acid and ascorbyl-palmitate

During the course of "PRO-SUGAR", the production of L-galactono-γ-lactone (L-GgL) from D-galacturonic acid was achieved by engineering Saccharomyces cerevisiae and optimizing fermentation processes. In "PRO-SUPER", this will be used as a new starting substrate for further transformation to L-ascorbic acid (L-AA) and ascorbyl palmitate. L-AA is an essential vitamin for humans and many other animals. Furthermore, it is used as a food additive in many products due to its antioxidant properties. Ascorbyl palmitate, on the other hand, can be used as an antioxidant in fatty foods and cosmetics and is recognized throughout the world as a food additive (E304).