ELECTROANALYTIC EVALUATION OF PHYSIOLOGICAL INTERACTIONS BETWEEN LACTOBACILLI AND STAPHYLOCOCCUS AUREUS

Abstract

Studying individual bacterial species in co-culture is crucial for understanding the specific properties and behaviours that emerge from the interactions between microorganisms in the natural environment. The present study aimed to evaluate the physiological and electrochemical properties of a co-culture of Lactobacilli and Staphylococcus aureus. To facilitate equal growth of the two antagonistic species, Compound Media was developed. The results showed that Lactobacilli species inhibited the planktonic growth and biofilm formation of S. aureus in co-culture under both aerobic and anaerobic conditions in CM media. Among the three tested Lactobacilli species, Lactobacillus plantarum was found to exhibit significant antimicrobial activity against S. aureus, indicating that the metabolites secreted by Lactobacilli could be used as a natural antimicrobial agent. To enhance the electroactivity of bacterial cells, a redox mediator known as 2-hydroxy-1,4-naphthoquinone (HNQ) was introduced into the culture media. The inclusion of HNQ at a concentration of 20 μM increased the current and total charge of both individual and co-cultured cells. The current and total charge of S. aureus were higher than those of L. plantarum, indicating a greater proliferation rate of S. aureus. The data suggested that HNQ at 20 μM concentration had a minimal impact on the growth and biofilm formation of both individual and co-cultured cells. These findings provide insights into the physiological interactions between Lactobacilli and S. aureus, which can aid in the development of new tools and approaches for combating bacterial infections. The electrochemical approach used in this study can also be applied to investigate interactions between different microorganisms and understand their physiological and electrochemical properties.