Fermented foods and new challenges in the use of bacteria

CONICET researchers studying new metabolic pathways in lactic acid bacteria. One potential way to develop high-quality food and control potential health risks .

For over ten years Christian Magni , biochemical and principal investigator of CONICET at the Laboratory of Physiology and Genetics of Lactic Acid Bacteria , Institute of Molecular and Cellular Biology of Rosario (IBR , CONICET- UNR) makes , studying the role of microorganisms in the production of fermented foods such as yogurt, cheese, wine and beer.

Currently his work is focused on the mechanisms of regulation of gene expression bacteria Enterococcus faecalis , which can be a probiotic that provides benefits to the individual’s health or well become an opportunistic pathogen .

In recent research , published in the journal PLoS ONE , Molecular Microbiology Applied and Environmental Microbiology , Magni and his team are described in different ways, so far unknown which guarantee E. faecalis growth , survival and persistence in acidic environments.

“Today there is a public demand for high quality food with sensory , higher nutritional value and reduction of toxic or potentially hazardous to health compounds ,” says Magni , study coordinator.

Lactic acid bacteria are the main group of microorganisms for the production of fermented foods. The survival of these microbes , which are continually subjected to acid stress, constitutes a fundamental line of research for the selection of strains for use in the preparation of food .

“These bacteria are specialized and engaged in fermentation processes and give particular characteristics to food, like the aroma, texture and flavor ,” says Magni adding that ” further improve conservation , since the vast majority are safe and in some cases beneficial to human and animal health. The study of the metabolic processes of these microorganisms is of high technological interest. ”

While the bacillus study, Enterococcus faecalis, was recognized as minimal clinical impact , in the past two decades have emerged important hospital pathogens in immunocompromised patients and intensive care. Although this bacterial species is generally recognized as safe for human consumption , there are many strains of Enterococcus that have properties of interest for the food industry .

“Our goal is to understand how this organism survives , what genetic determinants leading to its transformation and explain the dual behavior of the bacteria. For this, we delve into the beneficial and harmful aspects of the organism , resulting from the decarboxylating activity of certain organic acids , “says Magni .

The researcher adds that Enterococcus faecalis are able to metabolize citrate present in milk and contribute to the development of flavor in fermented dairy foods. Furthermore, this kind is able to metabolize amino acids in the production of certain toxic compounds. Both pathways were studied at the molecular level to understand when activated, how to repress and which have physiological consequences for the organism .

“In the laboratory have been characterized metabolic pathways that constitute mechanisms of resistance to acid stress. These paths are formed by a substrate transport system associated with one or more steps by decarboxylation . Knowing what , how and when these systems resistance to acid stress are expressed , is of strategic importance in improving the viability of the beneficial bacteria and reducing the survival of pathogenic “concludes the researcher.