Uso de bactérias do ácido lático isoladas de soro-fermento de queijo Porungo na fabricação e no controle de Staphylococcus aureus em queijo Minas Padrão

Abstract

The increasing demand for healthier foods with fewer synthetic ingredients has driven the development of products containing lactic acid bacteria (LAB), which offer significant health benefits and impart unique characteristics to foods. LAB have gained prominence due to their numerous properties, particularly their antimicrobial potential. These bacteria play a crucial role in fermentation, extending product shelf life and producing important metabolites. Cheeses, especially artisanal varieties such as Porungo cheese, are rich in LAB. This study aimed to document various sources of LAB isolation and review the main methods for their identification, characterization, and application in the production of fermented foods. Additionally, it sought to evaluate the biotechnological potential of eight LAB strains isolated from Porungo cheese whey ferment, with the goal of optimizing and enhancing cheese production quality. The isolates were identified using MALDI-TOF MS analysis and tested for susceptibility to 12 antibiotics, as well as for diacetyl production. The antibacterial potential of the isolates was assessed against Lactococcus lactis ATCC 19435 and Staphylococcus aureus ATCC 13565 using neutralized cell-free supernatants (CFS). The effect of temperature on the growth kinetics of the isolates and the pH change in whole milk was evaluated over 48 hours. The isolates Enterococcus faecium QP60 and Streptococcus infantarius QP6 were evaluated as adjunct and starter cultures in the production of Minas Padrão cheese, as well as for their ability to control S. aureus growth in the food matrix. Two isolates were identified as S. infantarius, two as Streptococcus lutetiensis, three as L. lactis, and one as E. faecium. Most LAB strains demonstrated sensitivity to multiple antibiotics, with six producing diacetyl. Only the CFS obtained from E. faecium QP60 showed antibacterial activity against L. lactis, but not against S. aureus. The biotechnological potential of the isolates revealed that Streptococcus species rapidly adapted and exhibited high growth rates in whole milk incubated between 30 and 40°C, with S. infantarius QP6 standing out. However, treatments using various LAB combinations did not show significant effectiveness in controlling S. aureus growth over 60 days. Furthermore, the maturation process of Minas Padrão cheese and the different treatments applied resulted in significant changes in the product's physicochemical characteristics. The results suggest that E. faecium QP60 and S. infantarius QP6 warrant further investigation and may be considered potential adjunct and bioprotective cultures.