It still has an influence on the fitness of the fly,[1] and it affects different life-history characteristics such as lifespan (life expectancy), resistance against pathogens (immunity) and metabolic processes (digestion).
Considering the comprehensive toolkit available for research in Drosophila, analysis of its microbiome could enhance our understanding of similar processes in other types of host-microbiota interactions, including those involving humans.
Microbiota plays key roles in the intestinal immune and metabolic responses via their fermentation product (short chain fatty acid), acetate.
[6] Mushroom feeder species like Drosophila falleni and Microdrosophila harbour many Lactobacillales and generally maintain high bacterial diversity in their guts.
[8] In the gut of Drosophila melanogaster the composition and action of the microbiome appears to be tightly regulated within compartments, that is different sections of the intestines.
While foregut and hindgut are lined with a cuticle formed by the ectodermal epithelium, the midgut is of endodermal origin.
In addition, the microbiota itself seems to control the expression of several Drosophila metabolic genes within the midgut, possibly to facilitate digestion of food.
[11] Recently, IMD pathway in the anterior midgut region has been proposed to play multi-pronged roles to modulate key metabolic and mechanic functions in the gut.
It is possible that the microbiota-induced proliferation of intestinal stem cells and associated metabolic homeostasis is important in this context.
[17] In contrast, the microbiota seems to have a negative effect on lifespan in older Drosophila melanogaster, because their removal in ageing flies increases longevity.
[18] In aged animals, immune responses may over-shoot, possibly harming the host and favoring colonization with pathogens (e.g. Gluconobacter morbifer).