Applying fertilizers to fields has been a standard farming practice for generations. The problem with these chemicals is that they end up in the air or in water runoff. Scientists at agriculture startup Pivot Bio say the key to delivering an important nutrient to crops has been at the plants’ roots all along—and the company is now preparing to offer farmers an alternative to fertilizer.
Pivot has developed microbes that it says can supply the nitrogen that plants need to grow. The San Francisco startup is preparing to launch its first product, a microbial treatment for corn, in the 2019 growing season. To support commercialization in the U.S, and eventually, other geographic regions, Pivot announced today it has raised $70 million in new financing.
The investment, a Series B funding round, was led by Breakthrough Energy Ventures, the $1 billion fund steered by chair of the board Bill Gates that invests in technologies that reduce greenhouse gas emissions. The investment comes as a growing number of companies are researching and commercializing different microbial products intended to help plants in various ways, such as improving nutrient uptake, or making them hardier against the stresses posed by drought or pests.
Pivot’s focus is nitrogen, which plants need for photosynthesis. Air supplies plenty of nitrogen, but plants need the gas converted into a usable form. Some crops, such as peas, beans, and soybeans, grow with bacteria on their roots that perform this process, called nitrogen fixation. Cereal crops, such as corn, don’t have nitrogen-fixing bacteria, which is one reason why these crops are rotated with legumes, such as soy. The residual nitrogen left by soy provides the nutrient to corn plants in the following season.
Corn and other cereal crops, such as barley and wheat, already have microbes that can perform nitrogen fixation, but they don’t do this because the genes for this function have been “turned off,” says Sarah Bloch, lead scientist and strain optimization lead for Pivot. The microbes evolved this way as a response to the fertilizer that has been applied to fields for years. Nitrogen fixation takes so much energy that if any nitrogen is available to the microbes, such as the nitrogen supplied by synthetic fertilizers, a microbe’s nitrogen fixation genes switch off, Bloch says.
The Pivot microbes come from soils in many U.S. locations were corn is grown. Pivot maps the soil microbiome to identify the microorganisms that have a relationship with corn and also have the genetic potential for nitrogen fixation. The company then applies its genetic engineering techniques to the microbial DNA, to “reawaken” the ability to perform nitrogen fixation.
“We take the genes that are naturally there but we fine-tune the way that they are expressed to make sure that these genes are turned on,” Bloch says.
Pivot’s approach sounds plausible, says Megan Andrews, project manager at the Plant Soil Microbial Consortium at North Carolina State University. A microbial product for nitrogen fixation would not necessarily need to attach to the root to work; it could be introduced into the soil and still provide nutrients to the plant, she says. Andrews was unfamiliar with Pivot, but she added that using microbes that are native to the corn plant’s microbiome makes it more likely that they won’t disrupt the microbial community. However, she cautioned that it’s still possible the Pivot microbes would cause unforeseen effects.
“There is always a concern about how it will impact the native microbial community—whether it will displace an existing [microbe], or change the function of the group,” Andrews says.
Bloch says Pivot has tested its microbes in field studies across many different U.S. locations, assessing whether the microbes attached to the plant roots, and whether the nitrogen fixation genes were turned on. Of particular interest to farmers, the tests also showed
