• Project Description
• Overview
• Background

• Ag43 Secretion System
• Overview
• Design
• Experiments
• Result
• Conclusion

• Other Systems
• His-tag Inactivation System
• Co-expression System
• Discussion

• Future Work

• Modeling

Future Work

Alpha-Defensin Non-commensal Bacteria Killing System

Overview

Through eating foods, we take a lot of bacteria in our body. Of course, if such bacteria stay inside our body, they cause various illnesses. To protect our body, we have various immune systems like antibody, macrophage, and this year’s our subject; AMPs. While we defend our body from the invasion of bacteria, we live in symbiosis with commensal bacteria. These kinds of bacteria help us mainly in our intestine. They help us in digesting food, synthesizing nutrients, defending our body from non-commensal bacteria etc. Then, how do we live together with them even we have immune systems to eliminate bacteria? The secret was found in a kind of AMPs that human have. It is said that in our intestine, a kind of AMPs, alpha-defensin is secret and kill only non-commensal bacteria. About mouse alpha-defensin, this function has already reported(Masuda et. al). About the human alpha-defensin, this function has not been reported, but by the same research group, similar function can be seen in human one. We thought if this AMP secretion system is injected to commensal bacteria, we can create new bio-device that kills non-commensal bacteria. We chose Lactobacillus casei as our chassis and cryptdin 4 from mouse intestine Paneth cells and human defensin 5 from human Paneth cells as alpha-defensins. Because L. casei is usually used for probiotics, we can use this bio-device for producing safer yogurt. The yogurt made of this bio-device is hardly contaminated by non-commensal bacteria. In addition, the bio-device doesn’t kill commensal bacteria, so we can use it with other probiotic commensal bacteria, like bifidobacterium bifidum.

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