Boost­ing pho­to­syn­thes­is for car­bon capture

To the point

• CO₂ reduc­tion: Two new research groups at the Max Planck Soci­ety are work­ing on a more effi­cient form of pho­to­syn­thes­is to break down and bind CO₂ using sunlight.
• Innov­at­ive meth­ods: The first research approach uses com­pu­ta­tion­al pro­tein design and dir­ec­ted evol­u­tion to devel­op arti­fi­cial enzymes that optim­ise pho­to­syn­thes­is. The second approach focuses on adap­ted cyanobac­teria that store more CO₂ in their cells.
• Car­bon cap­ture and util­isa­tion: In addi­tion to stor­ing CO₂, the groups also aim to use the car­bon cap­tured for sus­tain­able products – an import­ant com­pon­ent of a cir­cu­lar eco­nomy in the chem­ic­al industry. 

On 1 July 2025, the Max Planck Soci­ety will launch two new research groups that aim to make the core of pho­to­syn­thes­is sig­ni­fic­antly more effi­cient. With the help of sun­light, CO₂ will be broken down into its com­pon­ents and fixed. The research is still in its early stages. How­ever, if scal­ing proves suc­cess­ful, large amounts of atmo­spher­ic CO₂ could poten­tially be cap­tured. Still, there’s long way to go. And the two research group lead­ers and bio­chem­ists Adri­an Bunzel and Andreas Küffn­er are aware that today’s car­bon cap­ture solu­tions are too expens­ive and inef­fi­cient, and that the risks asso­ci­ated with under­ground stor­age or injec­tion are, in some cases, impossible to assess. Nev­er­the­less, cap­tur­ing car­bon from the atmo­sphere will remain neces­sary for dec­ades to come, espe­cially since emis­sions from sec­tors like chem­ic­als and cement can­not be com­pletely elim­in­ated. It is there­fore bet­ter to close the cur­rent research gaps today rather than tomorrow.

‘Nature is conservative’

Adri­an Bunzel was already research­ing so-called pho­to­act­ive enzymes for bio­lo­gic­al photo­vol­ta­ics as an early career-research group lead­er at ETH Zurich. Enzymes are nature’s cata­lysts and accel­er­ate bio­chem­ic­al reac­tions. His pho­toen­zymes gen­er­ate elec­tri­city using sun­light. At the Max Planck Insti­tute for Ter­restri­al Micro­bi­o­logy, Bunzel is now tar­get­ing new enzymes that, like plants, use the energy of sun­light to break down CO₂ molecules into their indi­vidu­al com­pon­ents and bind them. In nature, how­ever, pho­to­syn­thes­is only binds about one per­cent of the the­or­et­ic­ally avail­able car­bon in bio­mass due to very com­plex reac­tion path­ways. ​“Nature is con­ser­vat­ive”, says Tobi­as Erb, Dir­ect­or at the Max Planck Insti­tute for Ter­restri­al Micro­bi­o­logy. With pho­to­syn­thes­is, it has estab­lished a suf­fi­cient but inef­fi­cient way of break­ing down CO₂ using sunlight.

In his research, Adri­an Bunzel aims to pro­duce arti­fi­cial pho­toen­zymes that greatly sim­pli­fy nat­ur­al pho­to­syn­thes­is and sig­ni­fic­antly boost its effi­ciency.. He is rely­ing on two cut­ting-edge meth­ods: com­pu­ta­tion­al pro­tein design (– the com­puter-aided devel­op­ment of new pro­teins – and dir­ec­ted evol­u­tion, a tech­nique that mim­ics nat­ur­al evol­u­tion in the lab to optim­ise enzymes through muta­tion and selection.

Both meth­ods have been awar­ded the Nobel Prize in recent years. ​“It’s like learn­ing to fly”, says Erb. ​“We observed how birds fly and stud­ied lift. Then we built air­planes, but without wings. They don’t look like birds, but they do what they are sup­posed to do and, in some respects, even bet­ter, more spe­cific­ally, and more effi­ciently.” For Adri­an Bunzel, this opens the door to entirely new pos­sib­il­it­ies: This is pre­ci­sion bioen­gin­eer­ing. It’s no longer about how we manip­u­late bio­logy, but what we want to design,” he says. The new pos­sib­il­it­ies in pro­tein design allow us to ask: Which pro­teins add value, for example, in achiev­ing sus­tain­ab­il­ity goals? 

Bet­ter bac­teria for photosynthesis