Team:ECUST China/Description
Project Inspiration and Descriptions
Welcome to our Wiki! We are East China University of Science and Technology iGEM team and we are more than excited to share our project stories with you.
Inspiration
Everything all started from the nightmare of one of our group member—the notorious Rhinitis. He has to carry a whole package of tissue with him wherever he goes because of this. As he consuming increasing amount of tissue but having trouble finding a quick solution for Rhinitis, he asked himself is there anything he could do for all the trees vanished/that cannot be resurrected, so our team look into paper recycle industry.
Gladly, we found that there’s something to work on during recycling, that is paper can’t be recycled fully, during each recycling process, cellulose fibers will become shorter and shorter due to keratinization. And after 5-7 cycles, cellulose would be too short to recycle. So we want to utilized the cellulose that cannot be recycled and show greater value/make it reveals greater value.
Understanding the Current Market of Recycled Paper and its Limitations
With the widespread promotion of the concept of circular economy around the world, the recycling of waste pulp, a green raw material for papermaking, has been given more and more attention, and consequently, the demand for waste paper has risen substantially, which also promoted the growth of the global waste paper recovery rate.
According to statistics, the global waste paper recovery has reached 250 million tons in 2018. Due to its waste paper recycling system, Japan leads the world in both recycling rate and utilization rate, with 81.5% recycling rate and only 64.3% utilization rate. While paper utilization rate can not match recycling rate, and resources can’t be optimally allocated mainly due to the increasing proportion of short fibers in paper recycling.
The Economic Value of BC
Bacterial cellulose, hereafter this text will be abbreviated as BC, has the same chemical composition and structure as plant cellulose in pulp, but it has incomparable advantages: high purity, high degree of polymerization and crystallinity, high water holding capacity, good biocompatibility and biodegradability. As a porous reticulated nano-biopolymer, BC can be used as value-added medical materials, multi-functional textiles, functional food, electromagnetic materials, wastewater treatment filter materials and so on. In any way, BC has broad application prospects in various fields.
How does the Paper Transformer work？
Our project can be summarized as three parts—degradation of short fibers in waste pulp, synthetize of BC from former reaction products and applications of high value-added BC. Our chassis organisms will be chosen from Acetobacter xylinum, Clostridium thermophilus and Escherichia coli, and the winner strain will be expressing cellulase and cellulose synthase with highest enzyme activities. Here we firstly name our chassis organisms ‘Transformer’. Firstly, Transformer can secrete cellulose exonuclease and endonuclease, and hydrolyze the short fibers in the pretreated pulp into cellobiose. The cellulose endonucleases and exonucleases we use are not inhibited by cellobiose or glucose, so cellobiose is expected to accumulate continuously in fermentation broth. As cellobiose accumulates to a certain level, we will inactivate these two cellulases. At the same time, Transformer begins to express β-glucanase and bacterial cellulose synthase, and continuously produces bacterial cellulose through cellobiose→glucose→UDP-glucose→BC pathway.
A core part of our project is to achieve timing regulation in a single chassis organism. To achieve this goal, we will focus on realizing the following functions:
- 1. Accumulation of cellobiose;
- 2. Inactivation of cellulose endonuclease and exonuclease;
- 3. Utilization of cellobiose
Just as transformers can transform from ordinary cars to super combat robots, our Transformer can transform waste paper into BC, which would play a big role in medical, environmental industries, textiles and other fields.