Microbial interactions between carrion insect symbiont Yarrowia lipolytica and soil bacteria

This study explores how Yarrowia lipolytica, a yeast closely related to Yarrowia spp. found in burying beetle secretions, interacts with soil bacteria in a carrion environment. These microbial interactions may influence the beetles’ behavior and success in occupying carcasses and could affect decomposition processes, but are rarely studied. On decomposing carcasses, Yarrowia spp. encounters soil bacteria such as Streptomyces sp. Mg1 and Bacillus subtilis, both of which produce antimicrobial compounds that can inhibit yeast growth. However, Y. lipolytica also produces antimicrobial fatty acids—such as oleic, caprylic, and capric acids—that are particularly effective against Gram-negative bacteria.
To assess microbial competition, an agar-based assay is used: Y. lipolytica is spotted as six evenly spaced dots forming a vertical line, while the soil bacteria are spotted as six dots forming a perpendicular line. This spatial arrangement simulates microbial interactions across the surface of a carcass and allows for the observation of inhibition zones or coexistence patterns. Preliminary results indicated that Streptomyces sp. Mg1 and Bacillus subtilis both suppressed Y. lipolytica, with Streptomyces showing stronger inhibition. These findings suggest specific antagonistic relationships, enhancing our understanding of how microbial competition influences carrion resource partitioning and insect behavior. This research integrates microbial ecology with the behavioral ecology of decomposer insects, offering insights into community assembly and carrion utilization.