LACTIC ACID BACTERIA IN THE ETHANOLIC FERMENTATION: CHARACTERIZATION AND INTERACTION WITH INDUSTRIAL YEASTS

• Grant number: 24/23414-0
• Support Opportunities: Regular Research Grants
• Start date: September 01, 2025
• End date: February 29, 2028
• Field of knowledge: Biological Sciences - Microbiology - Applied Microbiology
• Principal Investigator: Sandra Regina Ceccato Antonini
• Grantee: Sandra Regina Ceccato Antonini
• Host Institution: Centro de Ciências Agrárias (CCA). Universidade Federal de São Carlos (UFSCAR). Araras , SP, Brazil
• Associated researchers: Maria Angelica Ganga

Abstract

The coexistence of lactic acid bacteria and yeasts can be observed in a number of fermentative processes such as in the production of kombucha, wine, sourdough and kefir. The interactions between these microorganisms guarantee the quality of the products and their survival in the process. Some of the mechanisms involved in these interactions have already been studied in these fermentative processes, but little is known about the interactions that occur between them - lactic acid bacteria and Saccharomyces cerevisiae - in the context of ethanol production, other than the fact that they reduce the fermentative performance. Recent work has demonstrated that lactic acid bacteria can be beneficial for fermentation, and this interaction can occur through a variety of mechanisms. Most studies have focused on the bacterium Limosilactobacillus fermentum as the most important bacterium causing damage to fermentation, however, there appears to be intraspecific variation regarding its effect on the process. Furthermore, other species, such as Lactobacillus vini, have been frequently reported in the industrial environment but little is known about their effect on the fermentation process, despite their recognized tolerance to acidity. Therefore, the present work aims to evaluate the profile (stress tolerance, growth in different sources of carbon, nitrogen and hydroxycinnamic acids) of lactic acid bacteria species most commonly found in the fermentative environment in order to better understand their competences and tolerance to stress and seeking to understand the interactions that occur with industrial yeasts. A number of 27 strains of lactic acid bacteria will be evaluated, of which 16 isolates have not yet been identified, and four industrial strains, including a genetically modified yeast, for which there is still no work showing its performance against contaminants. The aim is to identify metabolites produced by bacteria and yeasts when in a consortium in order to understand possible mechanisms of interspecific coexistence. The role of lactic acid bacteria, whether as contaminants harming the process or as stimulators of fermentation through some mechanism, still needs more focus in research. (AU)