An important field in sustainable industrial chemistry is the development of new applications for fats and oils. One of the promising applications is the use of fatty acid derivatives, e.g. dicarboxylic acid (DCA), as polymer building blocks. In contrast to conventional plastics, bioplastics are polymers derived from renewable biomass sources. In addition to their contribution to the conservation of fossil resources and reduction in CO2 emissions by waste incineration, many bioplastics are biodegradable. The majority of industrial DCA production for polyamide (PA) and polyester (PE) synthesis is still done via chemical synthesis. While short-chain DCA can be synthesized in high yields, costs of long-chain DCA production rise significantly due to the generation of various by-products and are connected mostly to a costly purification. Thus biotechnology provides novel biochemical approaches for long-chain DCA synthesis that can provide an eco-efficient process alternative . In the present article, strategies for the development of high-level production strains for long-chain DCA are illustrated. Basic strategies for strain development, in order to achieve an effective enrichment of DCA, require the knowledge of the respective biochemical pathways. These are discussed in detail. Furthermore an overview of fermentation strategies and characteristics of corresponding polymers is given

Transaldolase (Tal) is involved in the central carbon metabolism, i.e. the non-oxidative pentose phosphate pathway, and is therefore a ubiquitous enzyme. However, Tals show a low degree in sequence identity and vary in length within the enzyme family which previously led to the definition of five subfamilies. We wondered how this variation is conserved in structure and function. To answer this question we characterised and compared the Tals from Bacillus subtilis, Corynebacterium glutamicum and Escherichia coli, each belonging to a different subfamily, with respect to their biochemical properties and structures. The overall structure of the Tal domain, a (b ⁄ a) 8 -barrel fold, is well conserved between the different subfamilies but the enzymes show different degrees of oligomerisation (monomer, dimer and decamer). The substrate specificity of the three enzymes investigated is quite similar which is reflected in the conservation of the active site, the phosphate binding site as well as the position of a catalytically important water molecule. All decameric enzymes characterised so far appear to be heat stable no matter whether they originate from a mesophilic or thermophilic organism. Hence, the thermostability might be due to the structural properties, i.e. tight packing, of these enzymes. DatabaseThe crystal structures have been deposited in the Protein Data Bank with accession code 3R8R for BsTal and 3R5E for CgTal.

Langkettige, ungesättigte Dicarbonsäuren stellen interessante Monomere für die Herstellung von neuen Polyamiden und -estern dar. Chemisch sind diese nur schwer darstellbar, daher stellt die fermentative Herstellung eine attraktive Alternative dar. Durch Untersuchung von Wachstums- und Produktionsparametern konnte der Herstellungsprozess von 1,18-Oktadecendisäure mit dem Stamm Candida tropicalis verbessert und neue Erkenntnisse gewonnen werden