Pollutant lactose produces alcohol

Portuguese researchers have created a microorganism that eats lactose by removing the pollutant load from the serum

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Turning a serious environmental problem - the whey resulting from cheese production - into a profitable and "green" product. This was the objective of a study conducted by the Department of Biological Engineering (DEB) of the University of Minho in conjunction with the company Quinta dos Ingleses and Dairy Halos. Eight years of research led to the creation of a new microorganism, through genetic manipulation, capable of eating lactose and flaking.

In Portugal, one million tonnes of whey produced per cheese production is produced per day, at a rate of ten liters per kilo of cheese. It is a serum with a high organic concentration, which makes it one of the most polluting industrial effluents produced in Portugal. It consists basically of water, lactose (5%) and two proteins (1%).

The challenge of making it a less polluting and economically profitable product was accepted by researchers from the University of Minho. "We wanted to follow a philosophy still little explored in Portugal: to make a by-product that is now wasted on a raw material for other value-added products", perfecting an existing technique, said José Teixeira, DEB director and project leader.

At this moment, the economic use of whey is made in two stages. First, it is subjected to ultrafiltration which removes the two dominant proteins, α-lactalbumin and β-lactoglobulin, with a degree of protein concentration ranging from 35% to 80%. This is the case with a permeated liquid, composed basically of water and lactose.

"Even without the presence of proteins," said José Teixeira, "this solution continues to be polluting", so a second treatment, capable of removing the lactose, is required. This second step consists of the transformation of lactose into ethanol (common alcohol feed), through its fermentation by a microorganism inside a tank. That is, the permeated solution enters and alcohol and water come out fundamentally.

It was here that the team of researchers introduced a technology "made in Braga". Until now, and only from Portugal, a microorganism has been used which obliges us to work at a discontinued pace, in which solution and the microorganism are introduced into the tank and after fermentation all the products derived therefrom are withdrawn.

The alternative proposed by the researchers is a micro-organism capable of aggregating into flakes that can be retained inside a tank for the process to unfold continuously, increasing productivity. Through genetic manipulation "we took a microorganism with a flocculating capacity and caused it to gain the ability to metabolize lactose and turn it into alcohol," explained José Teixeira.

Both the proteins from the first stage of the process and the alcohol can be used as feedstock for other products with higher added value, while the remaining solution can be directed to a Wastewater Treatment Plant without unbalancing it.

In addition to the genetic research itself, the team of scientists surveyed the Portuguese business community and came to the conclusion that there is a demand for protein concentrate (for sports drinks, infant or dietetic or baking, for example), as well as for Alcohol (as a beverage additive).

José Teixeira is satisfied with the results obtained, so he wants to try to remove from the serum other proteins in lower quantities or find products with higher added value from lactose.

 - Alexandra Figueira