Researchers at Massachusetts Institute of Technology (MIT) have developed a new metabolic engineering technique to reduce the cost and environmental impact of producing liquid biofuels.

As the process to produce biofuels involves huge cost, developers have been facing difficulties to move to large-scale manufacturing of ethanol and other chemicals.

 One of the major problems faced by them is the contamination of fermentation vessels with other, unwanted microbes, MIT said.

Even though Ethanol is known to be toxic to most microorganisms, helping in avoiding contamination of the fermentation process, but it is not same in case of production of more advanced biofuels and biochemicals.

To prevent contamination from unwanted microbes, companies must use either steam sterilization or costly antibiotics.

To address this issue, researchers at MIT and the Cambridge startup Novogy have developed a new technique that enables producer microbes to gain the upper hand against unwanted invaders.

The technique prevents the need for expensive and potentially harmful sterilization methods.

The researchers have engineered microbes which have the ability to extract nitrogen and phosphorous from unconventional sources that could be added to the fermentation vessels, according to Gregory Stephanopoulos, the Willard Henry Dow Professor of Chemical Engineering and Biotechnology at MIT, and Joe Shaw, senior director of research and development at Novogy, who led the research.

Stephanopoulos said: “We created microbes that can utilize some xenobiotic compounds that contain nitrogen, such as melamine.”

“They need that special pathway to be able to utilize melamine, and if they don’t have it they cannot incorporate nitrogen, so they cannot grow.”

 MIT said the chances of engineered strains escaping and growing in an uncontrolled manner outside of the plant in a natural environment are extremely low.

In a strategy named as ROBUST (Robust Operation By Utilization of Substrate Technology), the researchers engineered E. coli with a synthetic six-step pathway that enables it to express enzymes needed to convert melamine to ammonia and carbon dioxide.

The researchers have found the engineered type rapidly outcompeting the control after experimenting with a mixed culture of the engineered E. coli strain and a naturally occurring strain.

Stephanopoulos said: “So by engineering the strains to make them capable of utilizing these unconventional sources of phosphorous and nitrogen, we give them an advantage that allows them to outcompete any other microbes that may invade the fermenter without sterilization.”