Understanding the rules governing the maintenance of biodiversity is crucial for our fundamental understanding, and ability to manage, natural systems. Classic ecological theory typically assumes that environmental fluctuations are a source of disturbance that hinders species persistence. In contrast, emerging fluctuation-dependent coexistence theory suggests that environmental variability can play a vital role in generating the regulatory feedbacks necessary for maintaining diversity. The gut microbial community of Drosophila melanogaster serves as an ideal system for testing fundamental ecological theory. The small size and rapid generation times of microbes make them highly tractable, while the host's frequent and varied nutrient intake allows us to effectively explore how resource fluctuations influence the dynamics of the community. Additionally, previous research has highlighted the importance of cross-feeding interactions between Lactobacillaceae and Acetobacteraceae, two core families of gut microbes in Drosophila melanogaster, as a key mechanism in the assembly of the gut microbiome.
Our study aims to understand the role of resource fluctuations in shaping community assembly in such a cross-feeding system. In our experiment, Lactiplanibacillus plantarum and Acetobacter pasteurianus were grown in mono-culture and co-culture under conditions of continuous and 48-hour pulsed supply of MRS media over six days within mini chemostat bioreactors. We tracked optical density throughout the experiment and quantified bacterial density at the endpoint by both optical density and counting colony-forming units on selective media. These preliminary results offer a broad overview of how resource fluctuations impact community assembly in a cross-feeding system under simple experimental conditions.