Scientists at the National Autonomous University of Mexico (UNAM) developed proteins to slow the growth of pathogenic bacteria Listeria monocytogenes, which may be present in areas where food is processed and transmitted to humans through dairy products, fish, sausages and contaminated vegetables.

This bacterium causes listeriosis, a disease that affects high-risk groups such as pregnant women, newborns, older adults or immunocompromised people; and its mortality rate is 20 to 30 percent, very high compared to other foodborne illnesses.

The proteins developed by UNAM students can be used to prepare auxiliary cleaning agents in the food industry, industrial canteens and spaces where milking is done to prepare dairy products, said Maricarmen Quirasco Baruch, an academic at the Faculty of Chemistry (FQ).

In 2010, listeriosis was the third leading cause of death related to foodborne illnesses in the United States –with 1,662 cases and 266 deaths. In Mexico there are no precise epidemiological statistics to assess its impact, but due to the severity of the infection, food regulations establish that it should be absent.

The researchers obtained peptides, low molecular weight proteins, from genetic engineering, and registered the patent “Recombinant bacteria with antilisterial action” before the Mexican Institute of Industrial Property (IMPI).

Maricarmen Quirasco Baruch and his postgraduate students of Biochemical Sciences obtained the place of the Program for the Promotion of Patentation and Innovation (PROFOPI 2019), organized by the Coordination of Innovation and Development, which research is evaluated by specialists outside the UNAM who consider parameters of technical feasibility, attraction for the market, business prospecting and social impact.

What we seek to protect with the patent are DNA sequences that had not been previously reported or studied. We cloned them and expressed in Escherichia coli with the production of peptides capable of killing Listeria monocytogenes.

These peptides are located in the membrane of the microorganism that will exterminate, they make pores through which intracellular compounds leave and the cell dies,” explained the academic of the Department of Food and Biotechnology of the CF.

The peptides could be used in the preparation of aerosols, liquids or wet towels to clean the teats of the udders of the cows, prior to milking, he exemplified.

You can also make coating films for meat or other products that include bacteriocins. In the future they could be included in the food formulation as an additive, although for this they need safety tests and verify that they are not toxic to humans,” said the specialist.

Cotija Cheese DNA

The patent gathers the results of several theses of postgraduate students of the UNAM. The first was by Alejandra Escobar Zepeda, who did the metagenomic analysis of Cotija cheese and studied the DNA sequences of this fermented product.

She then compared millions of sequencing data of microorganisms with existing public databases. “We found several sequences that seemed to code for bacteriocins or peptides that primarily produce lactic acid bacteria and inhibit the growth of other bacteria.” This doctoral work received in 2016 the National Prize in Food Science.

Subsequently, Alfredo Esquivel López and Eduardo Serrano Maldonado, graduate students, took these DNA sequences to make genetic constructions and modified Escherichia coli to produce recombinant proteins. Alfredo Esquivel experimentally produced the peptides and found that they had activity against Listeria monocytogenes, as part of his master’s thesis.

Quirasco Baruch explained that neither she nor her students, who are also authors of the patent, intended to protect the results of their investigations. “It happend as we realized we were facing something new; now we think that other aspects of the bioinformatics and metagenomic analyzes that we have could be patented and that we want to continue doing it with other products.”


Source: Agencia ID