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Team:Imperial/Project Background
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Background
Abstract
Cellulose is the most abundant organic polymer found in nature. Due to its versatility and ubiquity we find cellulose has applications in areas from medicine to textiles. Much of the cellulose we use is impure as it is derived from plants. Bacteria offer an alternative means of production that produces a cellulose that is purer and requires less processing. In our project we optimise the production of bacterial cellulose (BC) by engineering Gluconacetobacter xylinus and transferring the system into Escherichia coli. We also functionalise our cellulose in order to expand its mechanical, chemical and biological properties into new areas of use.
Bacterial Cellulose
A Better Cellulose...
Bacterial cellulose has the same molecular formula as plant cellulose but is not contaminated by other cell wall components such as lignin and hemicelluloses. This means that its processing is simple not requiring energy or chemicals to isolate the cellulose. This results in a greater degree of polymerisation and a more crystalline structure (Nishi et al. 1990).
With Many Applications...
Bacterial cellulose possesses useful mechanical properties that make it a useful material in many industries. Applications range from biomedical applications in wound dressings and tissue scaffolds (Gama et al. 2013) to high quality papers and diaphragms for high-performance speakers (Nishi et al. 1990). It’s use as a filtration material has also been previously investigated (Chen et al. 2009) as well as an adsorbent for metal ions (Oshima et al. 2008).
Produced by Bacteria...
Bacterial cellulose is known to be produced by several species, including Agrobacterium tumefaciens, species from the genus Acetobacter, and in very limited quantities, also in Escherichia coli (Monteiro et al., 2009; Setyawati et al, 2007; Keshk, 2014).
However one of the highest producing species is Gluconacetobacter xylinus (previously classified as Acetobacter xylinum) ( Lee et al., 2014). Gluconacetobacter species produce cellulose by synthesizing and extruding cellulose polymers through pores in the outer membrane, which aggregate into fibrils and larger ribbons (see Figure 1).
References
