PROJECT OVERVIEW
According to a survey, 77% of milk spoilage is due to Gram Positive Bacteria. Losses during delivery of milk to markets are mainly in the form of bacterial spoilage due to lack of cooling facilities and long distances to collection centres. The usable life of milk is extended for several days through techniques such as cooling or fermentation. Post pasteurization contamination of milk, particularly with Pseudomonas and some Gram-positive psychrophiles can occur.(Seema Rawat,2015). We have developed a novel system that produces cationic anti microbial peptides(cAMPs) to prolong the shelf life of milk by preventing bacterial contamination.
![](https://static.igem.org/mediawiki/2016/b/bf/T--SVCE_CHENNAI--ampout.png)
![](https://static.igem.org/mediawiki/2016/5/56/T--SVCE_CHENNAI--ampkill.png)
- Their peptide was effective against Gram-positive bacteria including Methicillin Resistant Staphylococcus aureus.
- It was moderately effective against Gram-negative bacteria.
- It had low haemolytic activity and very low toxicity towards human cells.
- Their peptide attacked the bacterial cell membrane by integrating itself into the membrane and causes membrane depolarization.
Lactoshield is designed to produce the AMPs upon activation by heat, which is practical considering that all Indian households boil the milk once before consumption. For regulating gene expression through an increase/decrease in temperature, several options can be explored, a couple of which are available in the iGEM DNA distribution kit.A λpR promoter with a mutant cI inhibits gene expression below 42°C. Another part, an RNA thermometer isolated from Bradyrhizobium japonicum can be used for temperature sensitive post-transcriptional regulation. This part too, initiates translation at 42°C. To read more about the temperature activated systems we used click here
![](https://static.igem.org/mediawiki/2016/f/f3/T--SVCE_CHENNAI--rnat.png)
For delivering the peptide the team took inspiration from 2012 iGEM Team Groningen and made a few modifications to their system to suit our needs. To read more about the delivery system click here