Jeff Miller, a microbiologist from the University of California, Los Angeles, told Science that the initiative will fund projects that test cause and effect. "We have incredibly interesting correlations between a certain type of bacterial community and obesity, or type 2 diabetes, or whether a plant is going to grow fast or not," he told the publication last year. This project could determine whether these conditions are the result of particular microorganisms, or if those microbes are present because of those conditions. It could also lead to the development of various tools for microbe research, such as one that can eliminate a single species while leaving all others untouched.

The government is earmarking $121 million in federal money, which is already part of the president's 2017 budget, for the project. Another $400 million is coming from non-government organizations, including the Bill and Melinda Gates Foundation. The couple's organization is giving $100 million to the project over four years' time to develop tools that can be used for the study of human and agricultural microbiomes. The White House has published a fact sheet right here, which also discusses previous federal involvement in microbe research.