A certain bacterium that is capable of being guided to transform waste into an industrial chemical currently sourced from palm oil has been developed by a team of researchers at the University of Toronto.

According to the team of researchers, this finding promises to potentially help create a more sustainable path to manufacturing medium-chain carboxylic acids (MCCAs), which is a family of molecules used in the making of cosmetics, cleaning products, agricultural feed, antimicrobials and nutritional supplements.

Currently, several of these chemicals are derived from palm kernel oil, the production of which has been criticized over its links to deforestation, biodiversity loss and weak supply-chain traceability.

The team of researchers suggests that bacterial fermentation could potentially offer an alternative solution wherein food waste and agricultural byproducts are converted into high-value chemicals rather than through a process that relies on crops.

“The chemicals we are targeting here are known as medium-chain carboxylic acids (MCCAs) or medium-chain fatty acids (MCFAs),” the team explained. “They are six to twelve carbon atoms long, and they are used in all kinds of things: agricultural feeds, cosmetics, antimicrobials, surfactants and much more. The global market for them is on the order of $3 billion.”

Specifically, the team focused on chain-elongating bacteria (CEBs), which are microbes that live without oxygen and that can naturally convert organic material into useful acids via fermentation, which is a process similar to how yeast produces alcohol.

The team suggests that because the bacteria can feed on waste streams rather than refined sugars, they could potentially lower costs while simultaneously reducing the food-based inputs used in current bio-manufacturing.

For now, the team is exploring the use of municipal food waste and byproducts from dairy processing.

Yet, the researchers caution that the microbes do not always make the most valuable product, explaining that they want them to produce octanoic acid, which is eight carbons long and one of the most high-value MCFAs, particularly because palm kernel oil doesn’t contain that much of it.

Oftentimes, the team has found that when they grow these CEBs, they tend to instead create butyrate, which is a less-valuable four-carbon molecule.

Controlling that switch, the researchers explained, is that the ratio of lactate to acetate — which are two compounds the bacteria consume — helps to determine if the microbes make longer-chain octanoic acid or shorter-chain butyrate.

Further, the team also identified the role of an enzyme called CoA transferase (CoAT), which reportedly separates bacteria that can produce higher-value longer molecules from those that stop at four-carbon products. In other words, the CoA transferase is different in the bacteria that make the longer molecules, acting on precursors that are already six or eight carbons long.

The researchers envision that these findings could one day help engineers design bioreactors that steer bacteria toward premium products rather than products of low-value outputs.

An article detailing the research, "Acetate utilization strategy in chain-elongating bacteria determines butyrate versus medium-chain carboxylate production," appears in the journal Nature Microbiology.