Difference between revisions of "Team:Nankai"

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Poly-γ-glutamic acid (γ-PGA) is an important,  naturally occurring polyamide consisting of D/L-glutamate monomers. Unlike  typical peptide linkages, the amide linkages inγ-PGA are  formed between the α-amino group and the  γ-carboxyl group. γ-PGA exhibits many favorable features such as biodegradable,  water soluble, edible and non-toxic to humans and the environment. Therefore,  it has been widely used in fields of foods, medicines, cosmetics and  agriculture and many unique applications, such as a sustained release material  and drug carrier, curable biological adhesive, biodegradable fibres, and highly  water absorbable hydrogels.<br>
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  Strains capable for producing γ-PGA  are divided into two categories based on their requirement for glutamate acid:  glutamate-dependent strains and glutamate-independent strains.  Glutamate-independent strains are preferable for industrial production because  of their low cost and simplified fermentation process. However, compared with  glutamate-dependent strains, their lower γ-PGA productivity limits their  industrial application.  Therefore,  the construction of a glutamate-independent strain with high γ-PGA yield is  important for industrial applications. <br>
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  <em>Bacillusamyloliquefaciens</em> LL3, isolated from fermented food, is a  glutamate-independent strain, which can produce 3-4 g/L γ-PGA with sucrose as  its carbon source and ammonium sulfate as its nitrogen source. The <em>B. amyloliquefaciens</em> LL3 strain was deposited in the China Center for Type Culture  Collection (CCTCC) with accession number CCTCC M 208109 and its whole genome has been sequenced in 2011. In this study,  we aimed to improve the γ-PGA production based on the <em>B. amyloliquefaciens </em>NK-1 strain (a derivative of LL3 strain with  its endogenous plasmid and <em>upp</em> gene  deleted).<br>
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In order to improve  γ-PGA production, we employed two strategies to fine-tune the synthetic  pathways and balance the metabolism in the glutamate-independent <em>B. amyloliquefaciens </em>NK-1 strain. Firstly,  we constructed a metabolic toggle switch in the NK-1 strain to inhibit the  expression of ODHC (2-oxoglutarate dehydrogenase complex) by adding IPTG in the  stationary stage and distribute the metabolic flux more frequently to be used  for γ-PGA precursor-glutamate synthesis. As scientists had found that the activity of ODHC was rather  low when glutamate was highly produced in a  <em>Corynebacterium&nbsp;glutamicum</em> strain. Second, to balance the increase  of endogenous glutamate production, we optimized the expression level of <em>pgsBCA</em> genes (responsible for γ-PGA synthesis) by replacing its native promoter to  seven different strength of promoters. Through these two strategies, we aimed  to obtain a γ-PGA production improved mutant strain. </p>
 
<h2> Welcome to iGEM 2015! </h2>
 
<h2> Welcome to iGEM 2015! </h2>
 
<p>Your team has been approved and you are ready to start the iGEM season! </p>
 
<p>Your team has been approved and you are ready to start the iGEM season! </p>

Revision as of 16:02, 14 July 2015

Medigo Blue, free responsive template

Poly-γ-glutamic acid (γ-PGA) is an important, naturally occurring polyamide consisting of D/L-glutamate monomers. Unlike typical peptide linkages, the amide linkages inγ-PGA are formed between the α-amino group and the γ-carboxyl group. γ-PGA exhibits many favorable features such as biodegradable, water soluble, edible and non-toxic to humans and the environment. Therefore, it has been widely used in fields of foods, medicines, cosmetics and agriculture and many unique applications, such as a sustained release material and drug carrier, curable biological adhesive, biodegradable fibres, and highly water absorbable hydrogels.

Strains capable for producing γ-PGA are divided into two categories based on their requirement for glutamate acid: glutamate-dependent strains and glutamate-independent strains. Glutamate-independent strains are preferable for industrial production because of their low cost and simplified fermentation process. However, compared with glutamate-dependent strains, their lower γ-PGA productivity limits their industrial application. Therefore, the construction of a glutamate-independent strain with high γ-PGA yield is important for industrial applications.

Bacillusamyloliquefaciens LL3, isolated from fermented food, is a glutamate-independent strain, which can produce 3-4 g/L γ-PGA with sucrose as its carbon source and ammonium sulfate as its nitrogen source. The B. amyloliquefaciens LL3 strain was deposited in the China Center for Type Culture Collection (CCTCC) with accession number CCTCC M 208109 and its whole genome has been sequenced in 2011. In this study, we aimed to improve the γ-PGA production based on the B. amyloliquefaciens NK-1 strain (a derivative of LL3 strain with its endogenous plasmid and upp gene deleted).

In order to improve γ-PGA production, we employed two strategies to fine-tune the synthetic pathways and balance the metabolism in the glutamate-independent B. amyloliquefaciens NK-1 strain. Firstly, we constructed a metabolic toggle switch in the NK-1 strain to inhibit the expression of ODHC (2-oxoglutarate dehydrogenase complex) by adding IPTG in the stationary stage and distribute the metabolic flux more frequently to be used for γ-PGA precursor-glutamate synthesis. As scientists had found that the activity of ODHC was rather low when glutamate was highly produced in a Corynebacterium glutamicum strain. Second, to balance the increase of endogenous glutamate production, we optimized the expression level of pgsBCA genes (responsible for γ-PGA synthesis) by replacing its native promoter to seven different strength of promoters. Through these two strategies, we aimed to obtain a γ-PGA production improved mutant strain.

Welcome to iGEM 2015!

Your team has been approved and you are ready to start the iGEM season!

Before you start:

Please read the following pages:

Styling your wiki

You may style this page as you like or you can simply leave the style as it is. You can easily keep the styling and edit the content of these default wiki pages with your project information and completely fulfill the requirement to document your project.

While you may not win Best Wiki with this styling, your team is still eligible for all other awards. This default wiki meets the requirements, it improves navigability and ease of use for visitors, and you should not feel it is necessary to style beyond what has been provided.

Editing your wiki

On this page you can document your project, introduce your team members, document your progress and share your iGEM experience with the rest of the world!

Click here to edit this page!

See tips on how to edit your wiki on the Template Documentation page.

Templates

This year we have created templates for teams to use freely. More information on how to use and edit the templates can be found on the Template Documentation page.

Tips

This wiki will be your team’s first interaction with the rest of the world, so here are a few tips to help you get started:

  • State your accomplishments! Tell people what you have achieved from the start.
  • Be clear about what you are doing and how you plan to do this.
  • You have a global audience! Consider the different backgrounds that your users come from.
  • Make sure information is easy to find; nothing should be more than 3 clicks away.
  • Avoid using very small fonts and low contrast colors; information should be easy to read.
  • Start documenting your project as early as possible; don’t leave anything to the last minute before the Wiki Freeze. For a complete list of deadlines visit the iGEM 2015 calendar
  • Have lots of fun!

Inspiration

You can also view other team wikis for inspiration! Here are some examples:

Uploading pictures and files

You can upload your pictures and files to the iGEM 2015 server. Remember to keep all your pictures and files within your team's namespace or at least include your team's name in the file name.
When you upload, set the "Destination Filename" to Team:YourOfficialTeamName/NameOfFile.jpg. (If you don't do this, someone else might upload a different file with the same "Destination Filename", and your file would be erased!)

CLICK HERE TO UPLOAD FILES