Author(s): Rebecca Kreutz
Mentor(s): John Chaston
Institution BYU
Previous studies of the relationship between Drosophila melanogaster and its microbiota have shown that the bacteria inside fruit flies can have a large effect on their life history strategy. Higher proportions of Acetobacter, a genus of aerobic bacteria, correlate with faster development to reproductive maturity and higher, earlier fecundity. Greater proportions of Lactobacillus, a genus of anaerobic bacteria, correlate with lower initial reproduction but longer lifespan and maintenance of somatic cells (Walters, 2019). This study will explore the relationship between the depth of the food that flies mature in and the proportion of anaerobic bacteria found in the flies. Previous testing has shown a significant negative correlation between food depth and proportional Lactobacillus abundance. However, in that experiment both volume and depth varied, which may have caused starvation selection in the flies. Because higher proportions of Lactobacillus promote fat storage, having less food available in the shallower vials may have selected for flies with more Lactobacillus and caused a negative correlation between food depth and bacterial proportions. To further refine our understanding of the relationship between flies, their environment, and their microbiota, I will prepare vials with varying amounts of food spread out to uniform depth, raise flies in them with a mixture of Acetobacter and Lactobacillus, homogenize the mature flies, and compare the proportions of bacteria across the different food volumes. If there is no significant correlation, then volume has no effect on microbiota composition and the negative correlation found earlier is the result of variation in depth. The findings of this experiment will reveal more about how D. melanogaster obtains its microbiota, and help us better understand host-microbe interactions.