Indian Institute of Technology Kharagpur was first established after Indian independence as a cradle for nurturing young, bright minds to solve inhouse problems of the country. With the proud motto “Dedicated to the service of nation”, we at iGEM IIT Kharagpur decided to tackle a problem which is a direct contributor to the most disturbing issue of Indian subcontinent in twenty first century - Food Insecurity.

Apart from obvious challenge of growing population, depreciating resources and inequitable distribution of wealth. However there are multiple sublayers to the issue which often get unnoticed due to their isolated, unstructured and unobserved nature. One issue is that of food spoilage. This too has many dimensions but perhaps the most underrated one is household level food spoilage. This is a major concern in our lives mainly because such problems have a direct impact on the health of a person, which is the most important thing.

A majority of Food spoilage issues are caused by the biochemical activities of a microbial community that grows in the prevailing conditions. Despite chill chains, chemical preservatives and a much better understanding of microbial food spoilage, it has been estimated that 25% of all foods produced globally is lost post harvest or post slaughter due to microbial spoilage. Each and every food product harbours its own specific and characteristic microflora at any given point in time during production and storage. This microflora is a function of raw material flora, processing, preservation and storage conditions. Despite the variability in all of the three, some very clear patterns emerge, and based on knowledge of a few chemical and physical parameters it is possible with great accuracy to predict which microorganisms will grow and dominate in a particular product. At the point of sensory rejection (spoilage), the so-called spoilage microflora (or spoilage association) is composed of microorganisms that have contributed to the spoilage and microorganisms that have grown but not caused unpleasant changes.

Some of the present tools that help in identifying food spoilage are CFU analysis, ATP bioluminescence assays, volatile compound analysis, Electrical impedance measurement etc.

Flaws: These are time-consuming, tedious, expensive and not accurate enough.

What if we are given a tool which could monitor food spoilage and in itself is harmless to the body?
Let us help you know about a cool application of Biotechnology as marker of food spoilage!

It has been 4 decades since it is known that bacteria possess cell to cell communication capability using a phenomenon known as Quorum sensing. The communication is stimulated via certain signal molecules that freely diffuse into the environment. As the bacterial population in a region increases, the concentration of signal molecules also increases. After a certain threshold concentration, these signal molecules bind to promoter and induce the gene of interest. This helps them to express their genes together and cause a larger impact. They also “become aware” of the concentration of their own species and of other species in their vicinity.

Recent research has highlighted as a fact the involvement of quorum sensing in food spoilage. The enzymatic activities that account for quality degradation of the food product are regulated by quorum sensing activity. Also, the quorum molecules (autoinducers) are detected in spoiled food products.

We aim to make a genetically engineered bacteria that senses the concentration of quorum signals (currently only AHL) and detects the amount of food spoiling bacteria by expressing a colour pigment if signal stimulus is beyond a threshold value. This does gives a binary check that if the food under detection is spoilt or not.

The engineered E.coli senses the concentration of other bacteria and triggers the expression of lycopene (red-coloured) pigment which can be easily observed with the naked eye.

Packets will have a pouch with a sample of product and our engineered bacteria. Detection of AHLs (in the case of food contamination) in the product sample will trigger the expression of the lycopene gene that will produce the red-coloured pigment (easily observable to the human eye).