Microbiome is a word that we are going to hear a great deal more about in the near future. It is the full complement of microorganisms microscopic life forms such as bacteria that inhabit a particular environment. For example the human microbiome comprises all of the microorganisms that live on and in our bodies, and it is huge.
There are 10-fold more bacterial cells in the human microbiome than there are human cells in our bodies. And from recent research we are learning that its composition is critical for good health; in fact some scientists now regard the human microbiome as an organ of our bodies. It may have roles in conditions such as diabetes, obesity, multiple sclerosis, and many other diseases.
With this in mind it is not surprising to learn that scientists are exploring microbiomes associated with many organisms and environments, particularly in agricultural research. An international team led by Jack Glibert of the University of Chicago is exploring the microbiomes of many habitats in a project called the Earth Microbiome. As part of this the team has looked at grapevines and the soils they grow in.
Their research shows that different parts of the grapevine have different bacterial communities. Interestingly, while these communities differ from each other they each reflect what is in the soil that the plant is growing in. Gilbert and colleagues propose that the soil is a reservoir of bacteria for these different microbial communities. They also found that this reservoir varied with soil chemical composition leading to the suggestion that a soil microbiome can be managed; different soil treatments will lead to different microbiome composition.
The scientists propose that perhaps the microbiome of soil in a vineyard is what determines terroir of a wine. Terroir is described as the interaction of, amongst other things, climate, geology and geography of a vineyard, and the genetics of a grapevine that come together to shape the sensory properties of a wine. This is one explanation for why a Shiraz from Barossa is different to a Shiraz from McLaren Vale.
The proposition that microbiome composition determines terroir deserves further research. If a viticulturist can shape the style of wine in a controlled manner by managing the microbiome of her or his vineyard, it opens the way for winemakers to more effectively shape their wines to meet market demands.
First published in Leading Agriculture Issue 6
Written by Paul Chambers – Research Manager Biosciences, Australian Wine Research Institute