Rice, potatoes, maize, corn. All seem relatively innocuous foods that we often need not think about twice. Yet they all make a foundational carbohydrate that not only forms a crucial part of the human diet, but is also a primary feedstock for the bioindustry and a central ingredient in manufacturing products such as paper and pharmaceuticals. Starch. It may not seem that changing the way we source this is a priority in our agricultural industries, but rising demand for starch-producing crops has led to problems with land and water scarcity, as well as causing harmful pesticides to leach into the surrounding environment. While a seemingly basic food substance, it is one with enough dietary and industrial importance to be worth considering in the bid to make our industries more sustainable.
A team of researchers from the Department of Strategic and Integrative Research at the Tianjin Institute of Industrial Biotechnology (an institute under the Chinese Academy of Sciences) has developed a novel way to make starch that takes crops out of the equation – instead using only carbon dioxide in the cultivation process. While the method remains in its nascent stages, if developed to become commercially viable it could provide a turning point in making starch more environmentally sound, without compromising our global food supply.
Time to starch
At present, starch is primarily produced by crops such as maize, which fix CO2 through photosynthesis in a process that reportedly has a theoretical energy conversion efficiency of around 2%. Now, the Chinese research team has developed a novel ‘hybrid system’ to make artificial starch using a bioreactor that eradicates the need for plants and has a far more rapid processing time. In this new method, an inorganic catalyst reduces CO2 to methanol before breaking it down further into carbon sugar units, and finally to polymeric starch.
“This artificial starch anabolic pathway relies on engineered recombinant enzymes from many different source organisms and can be tuned to produce amylose or amylopectin at excellent rates and efficiencies relative to other synthetic carbon fixation systems—and, depending on the metric used, even to field crops,” the team writes.
The process was created using a computational pathway design, and the team says it is 8.5 times faster than natural starch synthesis in maize, converting the carbon dioxide to starch at a rate of 22 nanomoles per minute. The researchers have also hypothesised solar and hydrogen sources could be used to power the process, with the artificial process converting solar to starch at a rate 3.5 times faster than in plants.
“We only need a few hours in the lab to complete the process which takes a few months by plants,” lead author and research associate Cai Tao told state broadcaster CCTV. “The annual production of starch in a 1 cubic metre (35 cubic foot) bioreactor theoretically equates to the annual yield from growing one-third of a hectare (35,500 square feet) of maize without considering the energy input.”
Producing starch in a lab or factory rather than on farms would not only save on land use, but also reduce carbon emissions and provide a greater sense of food security – for both human food as well as animal feedstocks.
While this may sound like a no-brainer alternative to traditional starch synthesis processes, there’s a catch. The method as it currently exists is a far cry from being economically viable, and demands far higher rates of energy than is environmentally sustainable, with the first step of converting CO2 to methane alone calling for temperatures and pressures high enough to potentially require fossil fuels to produce – ultimately proving an energy and cost intensive process.
Such issues certainly gives pause for thought, though the project thus far provides a significant foundation to be built upon – not only for starch but in the potential rise of synthetic biology in agriculture more generally.
Synthetic biology in agriculture
A 2020 research paper predicted global food production needs to be increased by 70% to meet demands by 2050 – something that current agricultural methods cannot achieve. As think tank Rethinkx writes: “We are on the cusp of the deepest, fastest, most consequential disruption in food and agricultural production since the first domestication of plants and animals ten thousand years ago.”
The agricultural biotechnology market is set to see a growth of 10.7% during the forecast period of 2021–2030. This of course extends beyond crops to encompass lab-grown meat and other proteins to feed the booming alternative-meat sector – with Rethinkx predicting that the number of cows in the US will have fallen by 50% in 2030 as demand for livestock drops.
Cultivating crops in a lab has long been identified as a means of reducing emissions and avoiding land use competition while still meeting growing demand for food, and the Tianjin Institute researchers are not alone in their mission to find ways of creating the foodstuff of our futures that curbs our crop reliance. Finnish food-tech startup Solar Foods has developed a fascinating method of producing food using electricity, air and a single microbe, in a process the group says is 20 times more efficient than photosynthesis. The substance produced is like a type of flour, which the group hopes can be used not only to replace fillers in a multitude of food products, but also provide a protein foundation for lab-grown fish and -with some modifications – palm oil.
With concerns over our land and water use rumbling, it will be increasingly common for innovators around the world to turn to other processes that offer a faster and less resource-demanding solution – and ones that provide an evergreen source of food. But we’re not entirely there yet, and the Tianjin Institute project certainly demands more research before it is economically competitive with existing processes. Yet once these kinks have been ironed out, these solutions will be the ones to crack the code on bolstering our food systems to meet both environmental and human demands.
