The inter-species interactions in microbial communities involve many complex chemical processes that remain largely unexplored.

Even in controlled experiments, the detailed interactions between two microbial species are not fully understood. Here,

we introduce a microfluidic co-cultivation technique that allows for the study of growth and interactions within microbial

consortia at the single-cell level. This straightforward method successfully co-encapsulates Staphylococcus epidermidis and

Staphylococcus aureus in a single droplet, creating a controlled environment. Unlike traditional methods, where average bulk

responses often obscure individual cell behaviors, the confined space of the droplet provides detailed observation of cellular

dynamics. Our method provides interesting information of microbial interactions, such as population dependencies, growth

constants, and doubling times. In this study, two distinct microbial species are selected to demonstrate the broad potential

of this technology. Our results show that co-cultivation in a limited space markedly affects the growth of each microbial

species and the growth kinetics depend on the ratio of the two species. We confirm that Staphylococcus epidermidis can

suppress the growth of the common pathogen, Staphylococcus aureus. This microfluidic co-encapsulation method opens a

solid platform for future research into both contactless and contact-based interactions within both natural and engineered

microbial communities.