In a first, Danish researchers including one of Indian origin, have engineered E. coli bacteria to develop a cell line that produces large quantities of the compound serine — used in detergents, tube feeding formula and as building blocks for many key chemicals. The researchers from The Novo Nordisk Foundation Center for Biosustainability (DTU Biosustain) believe this cell line will help produce the ingredients sustainably and at low cost.
“This discovery is quite unique and proves that we can actually adapt cells to tolerate large amounts of serine — something many people thought wasn’t possible,” said Professor Alex Toftgaard Nielsen from DTU Biosustain. In order to develop these cells, the team used highly specialised robots.
“Cell growth must be monitored 24 hours a day, and the cells must be transferred to new medium at a certain time of growth. Therefore, it is crucial that we use ‘Adaptive Laboratory Evolution’ (ALE) robots,” explained lead author Hemanshu Mundhada from Technical University of Denmark.
Serine is an amino acid important for humans because it is one of the 20 amino acids forming proteins in our bodies.
Being highly water soluble, serine finds application as moisturiser in lotions of pharma and cosmetic industry.
The first step in the development process was to produce E. coli cells that could survive high concentrations of serine.
To achieve this, the scientists used ALE method in which they first exposed the cells to a small amount of serine. When the cells had grown accustomed to these conditions, the bacteria were transferred to a slightly higher concentration. The experiment was repeated several times with the cells best suited to tolerate serine. The tolerant E. coli cells were subsequently optimised genetically to produce serine.
“We have shown that our E. coli cells can use regular sugar and even residues from sugar production, molasses, in lower concentrations,” Mundhada added in a paper published in the journal Metabolic Engineering.