Polyhydroxyalkanoates (PHAs) are polyesters composed of (R)-3-hydroxy-fatty acids. A variety of gram-positive as well as gram-negative bacteria and some archaea are able to produce these biopolymers as energy and carbon storage materials. In times of unbalanced growth, when carbon is available in excess but other nutrients are limited, PHA inclusions are formed. These granules are water-insoluble, stored intracellularly and can be maintained outside the cell as beads. The key enzyme for the formation of PHA inclusions is the PHA synthase PhaC, which catalyses the polymerization of (R)- 3-hydroxyacyl-CoA to PHA with the concomitant release of CoA. The PHA synthase from Ralstonia eutropha (currently Cupriavidus necator), which is covalently bound to the PHA granule surface, tolerates fusions to its N terminus without loss of activity. In this study it was investigated if it would also tolerate translational fusions to its C terminus. A specially designed linker was employed, aiming at maintaining the hydrophobic surroundings of the R. eutropha synthase C terminus to allow proper folding and activity. Two reporter proteins were tested as fusion partners, the maltose binding protein MalE and the green fluorescent protein GFP. As GFP is a hydrophobic protein itself, no additional linker between the PHA synthase and the reporter protein was necessary to produce PHA granules displaying the functional fusion protein on the surface. Principally, the PHA synthase PhaC tolerates translational fusions to its C terminus but the nature of the fusion partner influences the functionality. Recently, PHA granules have often been acknowledged as bio-beads. A one-step production allows the formation of functionalised beads without the need for further cross-linking to impart desired surface properties. PHA beads displaying a gold- or silica-binding peptide at the N terminus of PhaC were constructed and tested for their applicability. Additionally, these beads were able to bind IgG due to the ZZ domain of the IgG binding protein A, which was employed as a linker sequence. These functionalised beads can be used as molecular tools in bioimaging and biomedicine, combining organic core with inorganic-binding shell structures. In a different biomimetic approach, the display of ten lysine residues at the granule surface was achieved using the phasin protein PhaP as the anchoring matrix. Extensive work was performed in an attempt to also employ the synthase protein, but was unsuccessful. These positively charged bio-beads can be used for dispersion or crosslinking experiments as well as silica binding.

Food waste and fashion pollution are two of the significant global environmental issues throughout the recent past. In this research, it was investigated the feasibility of making a leather-like material from bread waste using biotechnology as the bridging mechanism. The waste bread collected from the supermarkets were used as the substrate to grow filamentous fungi species Rhizopus Delemar and Fusarium Venenatum. Tanning of fungal protein fibres was successfully performed using vegetable tanning, confirmed using FTIR and SEM images. Furthermore, glycerol and a biobased binder treatment was performed for the wet-laid fungal microfibre sheets produced. Overall, three potential materials were able to produce with tensile strengths ranging from 7.74 ± 0.55 MPa to 6.92 ± 0.51 MPa and the elongation% from 16.81 ± 1.61 to 4.82 ± 0.36. The binder treatment enhanced the hydrophobicity even after the glycerol treatment, an added functional advantage for retaining flexibility even after contact with moisture. The fungal functional material produced with bread waste can be tailored successfully into leather substitutes using an environmentally benign procedure.

Consumption of citrus fruits and citrus juice production creates wastes, which could be valorized by using it for cultivating fungi. Before cultivation, the medium needs to be sterilized though autoclavation. Larger volumes used when autoclaving requires longer heating cycles and therefore runs the risk of degrading the medium to a greater extent. This research examines the effects of the volume lemon waste medium used while sterilizing. The aim is to find the largest volume still providing good growth for the filamentous fungus used, Rhizopus Delemar. Lemon waste was provided by Herrljunga Musteri AB and was pre-treated at 45°C for 2h. The liquid was strained and autoclaved in different volumetric series ranging from 200 – 10 000 mL, that was then used in 200 mL shake flask cultivations.  A scale up in two 3,5 L bubble column reactors was also performed from the 10 000 mL autoclaved medium, after not observing severe impacts on growth. Testing was done by weighing biomass and HPLC analysis of sugars. The yield of the biomass in the shake flasks ranged from 0,11 – 0,14 g/g sugars and the biomass concentration ranged between 2,4 - 3,0 g/L. Overall, the volume of autoclavation seems to not too be of great concern when cultivating R. Delemar on lemon waste medium in the analyzed ranges.

Xyloglucans are polysaccharides found as storage polymers in seeds and tubers, and as cross-linking glycans in the cell wall of plants. Their structure is complex with intricate branching patterns, which contribute to the physical properties of the polysaccharide including its binding to and interaction with other glycans such as cellulose. Xyloglucan is widely used in bulk quantities in the food, textile and paper making industries. With an increasing interest in technically more advanced applications of xyloglucan, such as novel biocomposites, there is a need to understand and control the properties and interactions of xyloglucan with other compounds, to decipher the relationship between xyloglucan structure and function, and in particular the effect of different branching patterns. However, due to the structural heterogeneity of the polysaccharide as obtained from natural sources, relevant studies have not been possible to perform in practise. This fact has stimulated an interest in synthetic methods to obtain xyloglucan mimics and analogs with well-defined structure and decoration patterns. Glycosynthases are hydrolytically inactive mutant glycosidases that catalyse the formation of glycosidic linkages between glycosyl fluoride donors and glycoside acceptors. Since its first conception in 1998, the technology is emerging as a useful tool in the synthesis of large, complex polysaccharides. This thesis presents the generation and characterisation of glycosynthases based on xyloglucanase scaffolds for the synthesis of well-defined homogenous xyloglucan oligo- and polysaccharides with regular substitution patterns.