Human microbiome

Event Date: 
Wednesday, September 24, 2014 - 18:00 - 18:15
Institution: 
University of Sydney
Title: 

Microbiota characterisation in the Tasmanian devil

Abstract: 

The Tasmanian devil (Sarcophilus harrisii), the world’s largest remaining carnivorous marsupial, faces extinction due to the spread of a contagious cancer called Devil Facial Tumour Disease (DFTD). The lack of a description of the bacterial community composition in the species represents a major gap in our knowledge of Tasmanian devil biology. In this study we characterised 12 microbiomes from four body sites, including mouth, gut, skin and pouch, in five Tasmanian devils via PCR amplification of 16S rRNA gene V1-V3 regions followed by 454 sequencing.  A total of 249,224 reads with an average sequence length of 489 bp were obtained after length and quality filtering. The reads further clustered into 14533 operational taxonomic units (OTUs; sequence identity cutoff of >97%) that were classified to 24 phyla spanning 275 families. Higher levels of bacterial species richness were observed in the pouch and skin than in the mouth and gut. The pouch and skin showed similar microflora compositions, which may vary between animals, possibly due to different environments. Distinct from the previously reported koala gut microbiota [1], which is dominated by Bacteroidetes and Firmicutes, the devil gut microbiota was found to be dominated by Fusobacteria, Firmicutes and Proteobacteria, comprising up to 73.7-94.3% of the community. This study has greatly improved our understanding of the microbial communities in the Tasmanian devil, which will significantly contribute to the effort to conserve the species.

Event Date: 
Wednesday, March 26, 2014 - 18:15 - 18:30
Institution: 
Radboud University Nijmegen, Netherlands
Title: 

The gut microbiome of phytopathogenic root fly larvae: insights into the detoxification of plant secondary metabolites by insect-associated microbes

Abstract: 

Plants of the genus Brassica produce various toxic compounds such as isothiocyanates in response to herbivore damage. Despite their toxicity, some insects can cope well with these compounds. One example is the larva of the cabbage root fly (Delia radicum) which is a serious agricultural pest. The mechanism by which these root feeding insects detoxify isothiocyanates is not explored. Our hypothesis is that microorganisms residing in the gut contain enzymes that break down the isothiocyanates and are thus crucial for survival of the root fly larvae. We substantiated this hypothesis by metagenome studies of the microbial gut community. Combined with functional screens of isolated gut microbes these analyses indicated that indeed the gut microbiota plays a vital role in the breakdown of isothiocyanates. Some genes encoding proteins that are involved in this process have already been identified. Ongoing genome and transcriptome studies of isolated gut microbes will enable us to find new candidate genes encoding proteins used for isothiocyanate breakdown that will subsequently be functionally characterized. This will lead to an in-depth understanding of the role of microbes in the plant secondary metabolite – insect interaction.

Event Date: 
Wednesday, February 26, 2014 - 15:45 - 16:15
Institution: 
University of Perugia, Italy
Title: 

The intricate cross-talk of the microbiome in Resistance and Tolerance to pathogens

Abstract: 

The diverse microbial population characterizing the human host represents the result of different complex scenarios impacting the human microbiome assembly. The variety of the microbial species involved plays an important role on the human health by affecting the tissue differentiation, the modulation of the immune system as well as the general response against infectious pathogens, which has been recently revised and divided into two different strategies named Resistance and Tolerance. Resistance being the strategy where the host protects himself by reducing the pathogen load whereby the Tolerance being the opposite strategy, which consists in tolerating the pathogen to avoid tissue damage due to the occurrence of subsequent inflammatory pathologies. The host microbiome seems to play a crucial role in determining which strategy the host will exploit to avoid infection. We recently found that highly adaptive lactobacilli, switching from sugar to Tryptophan (Trp) as an energy source  are expanded and produce an aryl hydrocarbon receptor (AhR) ligand—indole-3-aldehyde—that contributes to AhR-dependent IL-22 transcription, which then trigger the release of antimicrobial peptides by the gut epithelium. Importantly, innate lymphocytes IL-22 producers were already described as a typical innate Resistance strategy to protect the host from intragastrical Candida albicans infections in mice. Thus, the resulting IL-22-dependent balanced mucosal response allows for survival of mixed microbial communities yet provides colonization resistance to the fungus Candida albicans. Therefore, the microbiota-AhR axis might represent an important strategy pursued by co-evolutive commensalism for fine-tuning host mucosal reactivity contingent on Trp catabolism.

Event Date: 
Wednesday, October 30, 2013 - 19:00 - 20:00
Institution: 
USyd
Title: 

How microbial community structure is shaped

Abstract: 

 
Microbes profoundly influence biological systems. Owing to their small individual size, but extremely large populations, their influence is typically an emergent property of the microbial community.  As such understanding how microbial community structure is shaped is a generic question relevant to almost all biological systems.
A major focus of my research is the interplay between diet, gut microbiota and health. Our health is the product of interplay between many different factors with arguably three of the most important being adequate nutrition, homeostatic regulation and exclusion of foreign cells. Gut functions influence all these, but occur in the immediate proximity of a huge community of microorganisms – our gut microbiome. The gut microbiome profoundly effects our health via its contribution to and influence on gut functions.
Arguably the most significant aspect of our gut microbiome is that differences in composition matter. The contribution of our microbiome to nutrition, metabolism, gut and immune functions varies from person-to-person. Thus the clinical manifestation of many diseases will be influenced by the individual’s microbiome. Secondly, environmental or lifestyle differences such as diet and hygiene may modulate microbiome composition and thus its influence on health. This gives rise to two basic opportunities for improving healthcare. These are, using the microbiome as a metric to improve diagnosis and targeting the microbiome for therapeutic intervention. We are specifically exploring forces that shape microbial community structure in mouse and human models of with a view to developing diagnostic and intervention strategies across a range of health issues. 

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