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.