It鈥檚 a mould breaker. Researchers have discovered the first fungus that behaves like a farmer.
We already know that soil fungi can help bacteria travel quickly from A to B. The fungal filaments provide favourable conditions for the bacteria, and so act as 鈥渉ighways鈥� through the soil. But these highways may impose a toll.
To find out more, at the University of Neuch芒tel, Switzerland, and her colleagues studied the soil fungus and its relationship with bacteria. To track the flow of nutrients, she labelled the fungus with carbon-13 in one experimental set-up, and labelled the bacteria with the isotope in a second. After five days, the bacteria had gained nutrients from the fungus.
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But between day five and day nine, the bacteria numbers began to drop and the nutrients flowed from bacteria into the fungus. At the same time, the fungus began growing hard, nutrient-rich nodules called sclerotia, which it uses as a food store during unfavourable times when nutrients are unavailable.
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Junier thinks the fungus first cultivates the bacteria by feeding them, and then harvests them. The fungus may actually eat the bacteria, although it鈥檚 not clear how. 鈥淲e think digestive enzymes are involved,鈥� she says.
鈥淭he interaction between fungi and bacteria certainly deserves further study,鈥� says at Wageningen University and Research Centre in The Netherlands. However, he is not convinced that the interaction qualifies as farming.
鈥淚t is unclear whether the documented carbon transfer from bacteria to fungus makes a nutritional difference for the fungus,鈥� says at the University of Texas at Austin.
However, at Washington University in St Louis, Missouri, is more receptive. In 2011 she documented the , in which the social amoeba cultivates and harvests bacteria.
鈥淢icrobes are still a largely unexplored frontier,鈥� she says. 鈥淚 am sure there are many, many amazing relationships among microbes waiting to be discovered and investigated.鈥�
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