According to an nddb survey, 77% of milk spoilage is due to gram positive bacteria. Loss of milk due to wastage during delivery to markets is 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 by its refrigeration. But this too depends heavily on a constant supply of electricity. Lactoperoxidase method for preserving milk can be done. But "leucocytes may activate LP-s through production of hydrogen peroxide, although their presence is obviously undesirable, reflecting mastitic infection. Hydrogen peroxide residues from disinfectant solutions following cleaning of milk containers may also activate the system."-Report of an FAO/WHO technical meeting. 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. And we make this possible without the hassle of huge equipments and machinery!
- 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.
While designing a system to deliver the AMPs, we took inspiration from the 2012 iGEM team Groningen to build the skeletal design for our project. To read more about the delivery system click here.
2. Michaela Wenzel et al,(2014) Small cationic antimicrobial peptides delocalize peripheral membrane proteins, E1409-E1418; DOI 10.1073.
3.Dairy processing and cold storage affect the milk coagulation properties in relation to cheese production (1.09). 01/2014; 95(1):101-114.
4.• Food and Agricultural Organisation of United States Report 2015