Tuning engineered microbial co-cultures to produce novel and functionalisable cellulose-elastin composites (Cellulastin)

点击翻译按钮获取中文摘要

Plants assemble the world’s most abundant biopolymer, cellulose, and weave it into a mechanically robust composite material by incorporation of different compounds, such as lignin, pectin or hemicellulose. Consequently, its compressive strength is enhanced, but also new characteristics emerge, e.g. lignin acts as a sealant to protect plants from water intrusion. Some specialised bacteria are also capable of assembling cellulose. However, they lack the ability to incorporate additional compounds. With the rise of synthetic biology it became possible to engineer these bacteria to mimic the way plants assemble cellulose-based composites and create enhanced, sustainable biopolymers. Unmodified bacterial cellulose, already an extraordinary polymer, is used in a broad range of applications today, e.g. in medicine as skin replacement or in food industry as bulking agent. To extend its application range and improve already existing products, it can be biologically modified by altering the cell growth medium composition or by post-synthesis chemical modifications. Both methods impose a considerable workload. Regardless of the modification possibilities, bacterial cellulose remains inelastic. Above a certain force threshold, single cellulose fibres lose their stability, and the cellulose fibers disintegrate into their components. Elastin-like polypeptides (ELPs), elastic and environment-responsive polymers, appear to be highly suited to complement bacterial cellulose to overcome the limitation of elasticity. Their capability to stretch and refold without altering the high tensile strength of cellulose could improve the ductility of the copolymer. Moreover, an ELP scaffolding structure can incorporate additional proteins in a site-specific manner to add additional features, such as biosensing, drug delivery, or biofunctionalisation. The proposed project challenges the current bacterial cellulose production and aims to crosslink ELPs within the bacterial cellulose mesh. By co-cultivating the cellulose producing strain Komagataeibacter rhaeticus with a protein secreting strain, e.g. Saccharomyces cerevisiae, a promising new composite material, “Cellulastin”, is created. Both organisms secrete different biopolymers which ideally fuse into a new and promising composite material with immense potential. Especially, the response to environmental stimuli of ELPs can be utilised to provide unique properties. This approach will enable the de novo synthesis of smart copolymers consisting of highly tunable, sustainable, and interwoven networks of cellulose and ELPs.