Team:BIT-China/Background

Add a banner to your wiki!

You can make the image 980px by 200px

Remember to call the file: "Team_BIT-China_banner.jpg"

• 

  Project

  Description Design Basic circuits Fine-regulation circuits
• 

  Modeling

  Basic circuits Fine-regulation circuits
• 

  Notebook

  Laboratory Notes Protocols
• 

  Judging

  Parts Submission Achievements
• 
• 

  Team

  Team Gallery
• 

  Practice

  Human Practice Collaboration
• 

  Safety

  Safety Q/A
• 

  Attributions

  Attributions Sponsors

Nowadays, fermentation industry is crucial for a country’s economy. In China, fermentation industry output reached 2,000 billion RMB in 2011, and till 2013, this number has increased to 3,000 billion RMB.(Figure 1.) Fermentation industry’s output accounts for about 3 percentage of GDP in China, and it’s predicted that the output will reach 10,000 billion at the end of 2015. As a result, optimizing fermentation process and improve productivity is important

However, problems concerning fluctuation of pH in fermentation is usually knotty. Firstly, enzymes produced by microorganisms can be tremendously influenced by environmental pH. The activity of enzyme will plummet at an improper pH, and eventually the fermentation effectiveness will decrease. Worse still, different pH can entirely change a microorganism’s fermentation products. For example, Aspergillus niger can produce citric acid at pH 2.0~3.0, while the product will be changed to oxalic acid at pH 6.5~7.5. As for corynebacterium glutamicum, the product is glutamate at pH 7.0~8.0 while at pH 5.0~5.8 the products are Glutamine and N-aceglutamide. Therefore, a suitable environmental pH is a key factor for higher fermentation productivity.

Figure1. Fermentation industry output from 2005 to 2013^[1]

To maintain fermentation pH range, people have found some methods to regulate the pH of fermentation liquor, such as probe detection technique combined with computer programs, and adding acid and alkali into fermenters straightly. However, environmental interference can strongly interrupt probe detection, and increase reaction time. What’s more, adding large amount of acid and alkali may cause unbalance pH in different areas in fermenter. Those problems will decrease fermentation productivity and effectiveness. More importantly, all of these methods which heavily rely on electrical technology will increase factories' costs and energy consumption, but none of them considered function of microorganisms themselves.

So, Can we regulate environmental pH in a more simple way and meanwhile maintain the effectiveness?

Is there any possibility to regulate environmental pH by microorganisms themselves?

Basing on these questions, we come up with our idea.Here is the bacteria, now it faces this serious problem: how to survive in acidic and alkaline environment, and regulate environment to neutral pH, to protect the fermentation world?

At that moment, pH controller appears. When the bacteria get this weapon, it can balance the pH to neutral level. To achieve these goals, we firstly constructed PC in E.coli, and designed two subsystems in gene circuits. First system is resistance system to ensure survival of bacterium and regulate intracellular pH, while the second system--regulation system, focuses on regulating environmental pH to suitable range.