Inspiration
India is still primarily an agrarian economy, with the sector contributing to almost 15.4 percent of the net Gross Domestic Product The World Factbook: India, n.d. and around 58.6 percent of the population is engaged in some form of agricultural activity. Agriculture is therefore, not only a means of income for a majority of the Indian population, but also a form of cultural identity for farmers across the nation. With agriculture forming such an important part of the cultural and emotional fabric of the country, it was only natural for us to choose a problem that greatly affected the livelihoods of farmers in the country.
A majority of our team members belong to the Indian states of Karnataka, Maharashtra, Tamil Nadu or Uttar Pradesh — states with the most arable land and states which are major producers of sugarcane (Saccharum officinarum). Sugarcane is not only the primary input in the production of sugar, but it is also an important input in many other industries such as ethanol production and power generation. The sugar industry is also one of the largest employers of the rural Indian population, providing around 500,000 jobs and impacting the lives of almost 50 million farmers. Evidently, sugarcane is also one of the most widely-grown cash-crop in the country and is cultivated on around 50 million hectares of land.
Figure 1: Sugarcane and allied industries
We therefore chose to work on a problem plaguing both sugarcane farmers and the sugar industry: the problem of post-harvest sucrose deterioration.
The Problem
Sugarcane is a perennial species of grass that is cultivated primarily for its high sucrose content. The plant contains an enzyme called invertase that cleaves sucrose to provide cells with fuel for the processes of respiration and energy and carbon source for the synthesis of chemical compounds. This enzyme plays an important role in sucrose metabolism and regulation Ansari, M. I., et al., 2013. In live cane, the sucrose, therefore, is present under a dynamic balance between its synthesis and utilisation. Once the cane is harvested, this equilibrium breaks down. Instead of maintaining the levels of sucrose, the cells — under stress due to the harvest — hastily break down the sucrose, using invertase, into its components: fructose and glucose.
To put this loss into perspective, harvested cane undergoes a reduction in weight by almost 7.4 to 17.0 percent and a reduction in the amount of sucrose by anywhere between 2 to 10 percent. These losses drastically affect both the farmer and the sugar mills.
Figure 2: The action of cell wall invertase on sucrose
The retrieval rate of sugar from sugarcane is just 10.25% and this is remarkably low for a country heavily dependent on agriculture, such as India. The income, and therefore the livelihoods, of sugarcane farmers are dependent on the quality of cane they grow, making them the victims of this problem. We therefore wanted to come up with a solution that effectuated grassroot-level changes for farmers like Swaminathan.
Current Practices
This problem of post-harvest sucrose deterioration is widely known in the sugar industry Saxena et al., 2010 but there have been no satisfactory solutions till date. The primary solution used currently to mitigate these losses is to reduce the time taken to transport the cane from the farm to the mill; however India faces acute land shortages which makes it difficult to place mills within reasonable distances of the farm. Moreover, most farmers in India still harvest their crop manually which increases the time period between harvesting, transport and sugar extraction.
Although mechanisation is a possible alternative, it exacerbates the problem when applied in unsuitable conditions Ghasemnejad and Jamshidi, 2011 and often results in quality deterioration Singh and Solomon, 2003. They also reported that mechanised harvesting and chopping of canes resulted in a quicker deterioration if the time between the harvest and crushing is delayed by more than 24 hours.
Our Solution
We propose to target the invertase enzyme responsible for this post-harvest loss by “neutralising” it with an anti-invertase enzyme produced by genetically-engineered Escherichia coli. The farmer would introduce our genetically-modified E. coli into the stem of the sugarcane by means of a polymer-based inoculant which would be injected into the sugarcane matrix. Once inside, the genetic circuit of the bacterial chassis is designed to exhibit anti-invertase activity regulated by the amount of fructose inside the sugarcane in a continuous and controlled manner.
Since our bacteria is closely involved with a consumable product we kept in mind the significance of biosafety and designed a robust three-tier failsafe mechanism. At every stage we have tried our best to consult with various stakeholders and subsequently revised our project design to bring it one step closer to being deployable in the market.
The COVID-19 pandemic has caused widespread economic damage to all sectors of the economy, including the sugar industry. Mills have been non-operational for a significant amount of time due to prevailing restrictions. Sugarcane that was already harvested is being stored for long without any form of preprocessing, thereby compounding the problem. This adds even greater relevance to our product.
Furthermore, sugarcane is also a major crop in countries such as Brazil, Mauritius, Mexico, Cuba and Indonesia. These countries too have been facing problems with post-harvest deterioration. We believe that our product can also be expanded for use in these areas of cultivation.
SugarGain is our way of making the world a sweeter place (quite literally!).
