Interactions between Drosophila and its gut microbiota

The composition of the gut microbiota in Drosophila

The GI tract of Drosophila is chronically infected with bacteria.  We are investigating how these bacteria influence the health and wellbeing of their insect host.  Because microbial associations with the animal GI tract are ancient - probably as ancient as animals with guts  - these studies should reveal fundamental biology of how microorganisms influence human health, and how disruption of the host-microbial interactions is linked to chronic metabolic and immunological diseases.

Drosophila is amenable to these investigations because axenic (germ-free) flies can be generated readily, the microbiota is dominated by just 5 taxa that are culturable, and the association can be resynthesized by allowing axenic Drosophila to feed on the bacteria of interest.

Figure  Drosophila and its bacteria.  For more details, see Wong et al. 2011, Ridley et al. 2013 and Wong et al. 2013.
The bacteria in these analyses were identified by pyrosequencing of 16S rRNA gene amplicons.  Analysis of our data has been facilitated by a bioinformatics tool 16SpeB (16S rRNA Species Boundary), developed by Adam Wong and Patrick Ng and designed to relate % sequence identity to previously described species limits of bacteria.  The manual and scripts to download and use 16SpeB are available as downloads here.

The impact of the gut microbiota on Drosophila nutrition

We are studying how the gut microbiota influences Drosophila nutrition, using axenically reared insects and various dietary manipulations, with host gene expression, metabolism and performance as read-outs of the host-microbial interaction. The effect of the microorganisms is complex because the composition (and probably activities) of the gut microbiota is influenced by diet. 

Elimination of the microbiota causes hyperlipidemia and hyperglycemia  of the Drosophila. The axenic flies and conventional flies (i.e. with unmanipulated microbiota) have comparable weight and protein content on some diets (illustrated below).  We are investigating the physiological basis of these effects.






Figure Weight and nutritional indices of  conventional and axenic flies .  Values of mean + SEM are shown.

 

Phylogenetic and functional diversity of interactions between drosophilid flies and their microbiota

With funding from the NSF Dimensions of Diversity Program, we are studying the impact of cooperative interactions on evolutionary diversification of animals and bacteria, in collaboration with Dr John Jaenike, University of Rochester, and Dr Greg Loeb (Entomology, Cornell).  Drosophilid flies and their gut microbiota are our experimental system.  We are investigating how taxonomy and function of the gut bacteria in various drosophilid flies are coupled both to each other and to the functional diversity of the flies. The impact of these interactions on the capacity of the flies to utilize and damage fruits, their competitive interactions, and their resistance to parasites,are also being investigated. We are using genomic methods to obtain an integrated understanding of how animal-bacterial interactions shape the taxonomic and functional diversity of both the animal and its microbiota. 

Figure Our research involves multiple drosophilid species that feed and mate on different substrates, including (a) fungi (e.g. D. recens), (b) skunk cabbage (e.g. D. quinaria), (c) rotting fruit (e.g. D. melanogaster). Exceptionally (d) D. suzukii uses ripe fruit and is a major invasive pest in USA, including up-state New York.