Genetic engineering can transform Escherichia coli bacteria into tiny ‘factories’ that efficiently produce valuable chemicals — and have a small carbon footprint.

Microbial factories that turn renewable feedstocks such as simple sugars into ethanol or other useful commodities have been touted for their sustainability. But their productivity depends on many factors, including the lifespan of the bacteria themselves.

Liming Liu and his colleagues at Jiangnan University in Wuxi, China, singled out specific genes associated with ageing in E. coli. By deleting these genes or boosting their activity, the team changed the microbes’ lifespan to optimize their yield of two products.

The researchers found that reducing the number of times E. coli cells divide during their lifetime allowed the bacteria to produce 50% more of a biodegradable polymer. By contrast, when the scientists instead extended the microbes’ overall lifetime, the bacteria could produce high concentrations of butyrate, a compound used in pharmaceuticals and by the food and beverage industry, among others.