Team:Imperial/Mass Production and Processing


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Imperial iGEM 2014

Mass Production and Processing


Figure 1: Blue dyed bacterial cellulose

Bacterial cellulose (BC) exhibits a multitude of different properties depending on the processing, growth conditions, functionalisation and strain used (Bismarck 2013) for production of the material. Acquiring large quantities of cellulose produced would allow testing of a broad variety of cellulose processing methods and functionalisation steps.

By mass producing cellulose this enables a better understanding of what material properties can be realistically produced during the short duration of iGEM. More importantly, it improves the likelihood of finding suitable processing candidates for the project’s aim of making a customisable ultrafiltration membrane, at the same time as allowing room for creativity and exploration of the remarkable properties of cellulose.

Minimum requirements

  1. Treatment of BC requires killing the cells, particularly if the cells are genetically engineered, which is the aim for putting the customisable in ultrafiltration membranes.
  2. Based on brainstorming with Central Saint Martins student Zuzana, removing the colour of BC is required as it looks displeasing to the eye otherwise, and seems counter-intuituve to filter clean water with cellulose coloured like turbid water.
  3. Removal of the smell of BC has also been raised as a requirement, particularly by producers who work in close contact with the processing facilities.

Mass Production Methods

Figure 2. left: A granular pellicle, right: even pellicle

Setting up the mass production of cellulose was done according to the Kombucha media protocol , which involved setting up 61 trays with media and G. xylinus and yeast co-culture as shown in figure 3. The trays were left to grow up over 7 days, after which diminishing pellicle growth was detected. Upon harvesting, the pellicles were sorted according to granular pellicles (see figure 2 left) and even pellicles (figure 2 right). All pellicles were kept in distilled water in large plastic buckets or containers.

Below shows the general workflow we employed to mass produce our cellulose and illustrates the process of manufacturing biomaterials with significantly different properties despite originating from the same BC source.


We have made water filter grade bacterial cellulose. From different trial and error, we tried making leather cellulose that can be used a potential fabric garment. We produced bacterial cellulose on a scale larger than any previous iGEM team has produced a biomaterial in the Manufacturing track. This has provided us with opportunities to try treating cellulose with different low tech solutions that have been identified as invaluable to our collaborating Chemical Engineer Dr. Koonyang Lee. In his own words, we have produced more bacterial cellulose than he did during both his PhD and postdoc on BC, and come up with some simple solutions for practical issues. The ideas of ours that Dr. Lee has decided to carry on include using silicon coated baking paper in the protocol for measuring yield of BC to avoid BC sticking to the surface, and effectively using a non-bleach fabric stain remover to clean the BC thereby reducing the harmful impact of research in this area.

Key Achievements

  • Introduced a new aspect to the manufacturing track in terms of quantitatively characterising the mechanical properties of our product, bacterial cellulose
  • Quantified the tensile stress-strain properties of our bacterial cellulose.
  • Discovered that our bacterial cellulose can sustain an order of magnitude higher water pressures than those typically used for ultrafiltration membranes.
  • Established that non-blended compared to blended bacterial cellulose was significantly more ductile, and would have longer life time as a water filter, which informed the choice of cellulose for the final product.
  • Tested and analysed 20 samples of bacterial cellulose test pieces.
  • Created a size and quality optimised gif for visualisation of the experiment and written a protocol for future iGEM teams to do the same.