Team:KEYSTONE/Implementation
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Our clients
Medical workers
The need for degradation of medical waste is an immediate need for those working in the medical field. From the 2020 outbreak to the present, the medical pressure from the epidemic has led to a surge in the use of medical gloves, according to the Malaysian Rubber Glove Manufacturers Association (MARGMA), the increase in the demand of medical gloves during the COVID-19 pandemic is 57% higher than that of before the pandemic. This created a considerable amount of rubber gloves waste. Conventional rubber requires centralized processing, which is inconvenient and inefficient given the sporadic and migratory nature of
epidemic's health care sites, not to mention the numerous pollution problems associated with traditional methods as exposed in human practice (more information in Human Practice)..
Similarly, the main component of rubber medical gloves is polyisoprene, which can be degraded by our product——LCP (Latex Clearing Protein). a small movable E.coli fermenter producing Lcp comes into being.
Practitioners and local residents who handle rubber
Our products are also of value to practitioners in traditional rubber. According to the Xinhua News Agency, the amount of waste tires in China is as high as 20 million tons. What is even more frightening is that the production of tires in China is growing at a rate of 15% per year, and the amount of conveyor belts made of rubber is increasing by more than 10 million square meters per year. Large amounts of rubber enter the incineration or burial process, and these stimulate the volatilization of toxic gases. The stable chemical bonds of rubber products make them difficult to degrade chemically. Emissions pose serious acute (short-term) and chronic (long-term) health hazards to workers and nearby residents. Depending on the duration and level of exposure, these health effects may include skin, eye and mucous membrane irritation, respiratory effects, central nervous system depression, and cancer.
But latex clearing protein is the answer to this problem. A cell factory with E.coli as the chassis organism can degrade rubber harmlessly and sustainably, avoiding the above-mentioned health threat to people in the vicinity.
Left: BSV Tire recycling. [Photograph]. (n.d.).
Right: wkers in a rubber factory in Haifa [Photograph]. (n.d.). Wikemedia.
Real world application ——Industrial fermentation
In order to achieve a sustainable cleavage of the rubbers and tires, we introduce latex clearing protein. The latex clearing protein belongs to the group of enzymes for oxidative cleavage of poly(cis-1,4-isoprene) ---which is the chemical basis for most of the synthesizing rubbers on the market. Lcp, which stands for latex clearing protein, is an extracellular dioxygenase that has the ability to decompose rubber by endo-cleaving the poly(cis-1, 4-isoprene) into pieces.
E.coli with LCP can be rapidly cultivated based on industrial fermentation processes. The selection and breeding of high-performance production strains is carried out first. The methods include:
1. Select the chassis organism (eg.E.coli strain) that can express Lcp.
2. Select the Lcp that can be fully expressed and improve its performance to make it efficient.
3. Determine the optimal fermentation conditions (pH, temperature, dissolved oxygen, and nutrient composition) of the host bacteria, and the relevant carbon source is prepared.
4. Carry out the midstream process——under optimal fermentation conditions, mass cultivation of cells and production of metabolites can be started in the fermenter. To maintain a sterile operating environment during the midstream fermentation process, it is necessary to master the technology of sterilizing the fermentation material and the fermenter and the various piping connections at high temperature and pressure before the fermentation starts; the technology of air filtration, which continuously introduces dry sterile air into the fermenter during the fermentation process; the technology of computer control, which controls the dosing rate according to the cell growth requirements during the fermentation process; and the technology of seed culture and production culture. different process technologies.
5. Collect the target product. Since our proteins are secreted with the help of signal peptides, we do not need to go through the traditional crushing and centrifugation method.
With this approach to mass production, we can simplify the fermentation process and obtain significant protein yields to solve the problem of mass degradation.
There are mainly two most common fermentation methods:
1. Batch fermentation with replenishment.We will use large-scale fermentation for the plant instead of the traditional rubber waste ineffective disposal method (incineration and burial) to achieve a sustainable and harmless rubber degradation anti-method.
2. continuous fermentation. We will use the small type of rubber waste degradation for mobile health care sites (e.g. COVID-19 testing sites) to degrade rubber on a small scale and in real-time, so that this beneficial rubber degradation method will be more available in all areas and scenarios to reduce rubber pollution as much as possible.
Industrial fermentation often takes place in large steel tanks designed to house the process(Losevsky, P. (n.d.).
Safety considerations
The host bacteria---E.coli BL21 strain belongs to the risk group 1, with the potential danger of causing diarrhea.
Therefore, the fermentation process needs to be strictly controlled to prevent bacterial leakage and the risk of contamination of the strain. The measures to prevent contamination by tramp bacteria are to keep the fermenter piping free of dead spots that cannot be removed, disinfect it regularly, and change the filters regularly. In the case of bacterial leakage, operators need to wear protective clothing and gloves at all times that meet experimental safety requirements to prevent the risk of bacterial and nutrient spills.