Researchers in the US have published a study suggesting that the characteristics associated with terroir could have more to do with microbes found around the root system of a vine, than the soil that it grows in.

The study was carried out on Merlot vines in New York

The findings, from the Argonne National Laboratory in Illinois, were published in the online journal for the American Society for Microbiology, and raise the possibility that managing the bacteria in soil will provide a way to massage a wine’s character and taste.

‘Growers have been sub-selecting the best regions to grow grapes over thousands of years, but the science is poorly understood,’ Jack Gilbert, a microbial ecologist at Argonne, said of the study. He added ‘[It is clear that] bacteria have intricate associations with plants that affect disease resistance, stress tolerance and productivity.’

The study was carried out on Merlot vines growing in five different vineyards in the North Fork of Long Island. Samples of soil, roots, leaves, flowers and grapes were analysed throughout the growing season, and all bacterial species were identified and their genes sequenced. The New York microbiome was then compared to Merlot from both Bordeaux and California, with all three showing similar bacterial species.

The majority of bacterial species found in the plant were also present in the soil it was growing in, indicating that the soil acts as a reservoir for the bacteria.

Dr Paul Chambers, a researcher in bioscience at the Australian Wine Research Institute, said of the study, ‘If a viticulturist can shape the style of wine in a controlled manner by managing the microbiome of her or his vineyard in a targeted way, it opens the way for winemakers to more effectively shape their wines to meet market demands.’

Gilbert added, ‘From the wine industry’s perspective, terroir comes from the plant’s physiology, the chemical nature of the grapes, and the yeast that do the fermenting work.

‘We don’t have evidence that bacteria are specifically contributing to terroir, but our next step is to figure out how those bacteria are affecting the chemistry of the plant.

‘Unfortunately, flavour profile is a highly subjective area, and getting results there may take a little longer – but that is absolutely the direction that we are taking this in.’

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Written by Jane Anson in Bordeaux