The effect of gut microbiota elimination in Drosophila melanogaster: A how‐to guide for host–microbiota studies

Abstract

In recent years, there has been a surge in interest in the effects of the microbiota on the host. Increasingly, we are coming to understand the importance of the gut microbiota in modulating host physiology, ecology, behavior, and evolution. One method utilized to evaluate the effect of the microbiota is to suppress or eliminate it, and compare the effect on the host with that of untreated individuals. In this study, we evaluate some of these commonly used methods in the model organism, Drosophila melanogaster. We test the efficacy of a low‐dose streptomycin diet, egg dechorionation, and an axenic or sterile diet, in the removal of gut bacteria within this species in a fully factorial design. We further determine potential side effects of these methods on host physiology by performing a series of standard physiological assays. Our results showed that individuals from all treatments took significantly longer to develop, and weighed less, compared to normal flies. Males and females that had undergone egg dechorionation weighed significantly less than streptomycin reared individuals. Similarly, axenic female flies, but not males, were much less active when analyzed in a locomotion assay. All methods decreased the egg to adult survival, with egg dechorionation inducing significantly higher mortality. We conclude that low‐dose streptomycin added to the dietary media is more effective at removing the gut bacteria than egg dechorionation and has somewhat less detrimental effects to host physiology. More importantly, this method is the most practical and reliable for use in behavioral research. Our study raises the important issue that the efficacy of and impacts on the host of these methods require investigation in a case‐by‐case manner, rather than assuming homogeneity across species and laboratories.

A potential role for the gut microbiota in the specialisation of Drosophila sechellia to its toxic host noni (Morinda citrifolia)

“…Sharon et al, 2010), age (Zerofsky et al, 2005), or strain (e.g. discussed in Heys et al, 2018b). When reared on a standard Drosophila diet (0% acid concentration), our study determined that L. plantarum is present within both the D. melanogaster and D. sechellia gut.…”

Drosophila Sexual Attractiveness in Older Males Is Mediated by Their Microbiota

“…In a previous study, copulation duration was found to vary according to microbiota impairment, and authors acknowledged that the use of antibiotics could have more general physiological effect on the flies [25]. However, the use of low-dose antibiotics such as streptomycin, has recently been found to be more reliable and less detrimental to fly health than other methods of disrupting the gut microbiota [40]. Antibiotic use resulted in minimal impacts on a number of life history traits, including weight, development time and egg-to-adult survival.…”

“…The microbiota was impaired via the addition of the antibiotic streptomycin (4 mL of 10 g streptomycin/100mL ethanol solution per litre of growth medium) to the standard growth medium. Adding antibiotics to dietary medium is a common method to suppress insect microbiota [23,38], and has few side effects in Drosophila [39,40] when used at low concentrations. As the core composition of the Drosophila gut is known to be cultivable and relatively simple [41], we used culturable bacteria as a proxy to determine whether the microbiota had been impaired or not.…”

Drosophila melanogaster as an alternative model organism in nutrigenomics

“…Sterile or axenic fly strains (reared under germfree conditions) may be generated either by applying low doses of streptomycin to the diet or by performing egg dechorionation [43]. To obtain flies with a defined microbial community (gnotobiotic flies), flies will either be exposed to correspondingly inoculated sterile diets or embryos will encounter microbial species of interest [44].…”