One of the fears of critics of genetically modified organisms (GMOs) is that the plants will spread into the surrounding environment. Many GMOs are more resistant than traditional crops to insect pests and weeds.

To date of GMOs spreading beyond their desired habitat and into the broader ecosystem. However even Bill Nye, normally an ardent defender of science, has expressed concerns about the ecological impact of GMOs “…although you can know what happens to any individual species that you modify, you cannot be certain what will happen to the ecosystem,” said Nye in a 2014 Reddit AMA.

New research published in the journal Nature on Jan. 21 should help put concerns like Nye’s to rest. In the study, researchers from Harvard and Yale demonstrated a method to control the growth of GMOs by controlling access to amino acids necessary for growth.

Amino acids are the building blocks of proteins and proteins carry out life’s functions. In their research, the team rewrote the DNA of a strain of bacteria so that it requires a specific type of amino acid for growth. The particular amino acid that they made the bacteria dependent upon does not occur in nature.

That means that as soon as the amino acid is no longer provided to the bacteria by humans, it can no longer grow, spread or reproduce.

“This is a significant improvement over existing biocontainment approaches for genetically modified organisms. This work establishes important safeguards for organisms in agricultural settings, and more broadly, for their use in environmental bioremediation and even in medical therapies,” said Farren Isaacs in a statement.

Isaacs is an assistant professor at Yale in the Department of Molecular, Cellular, and Developmental Biology and the Systems Biology Institute at West Campus, and senior author of the paper.

Isaacs and his fellow synthetic biologists refer to these bacteria as genomically recoded organisms (GROs) because of the new genetic code. The code, linking the growth to synthetic amino acids, creates effective “biocontainment” and a safeguard against the spread of modified species in fragile ecosystems.

In a second, related study published January 21 in Nucleic Acids Research the team laid out a strategy that calls for multiple safeguards. The authors believe that these strategies may calm fears about GMOs and allow more widespread growth and use of the organisms for pharmaceuticals, fuel, food production, the fabrication of new chemicals and designer probiotics as well as specialized microorganisms that clean oil spills and landfills.

“As synthetic biology leads to the emergence of more sophisticated GMOs to address these grand challenges, we must assume a proactive role in establishing safe and efficacious solutions for biotechnology, similar to those who worked to secure the Internet in the 1990s.” Isaacs said.

Considerable research has been done on the potential environmental impact of GMOs.

“Environmental impact studies are predominant in the body of GM research, making up 68% of the 1,783 studies. These studies investigated environmental impact on the crop-level, farm-level and landscape-level. [University of Perugia applied biologist Allesandro] Nicolia and his team found “little to no evidence” that GM crops have a negative environmental impact on their surroundings,” according to Jon Entine of Forbes.

Despite extensive research however, fears among certain sectors of the public remain.