Azolla for the circular economy

Azolla for the circular economy


ResearcherID: D-6283-2011

For a  movie on the Azolla project click the following Link

The year 2012 saw the start of a new research line on a promising new crop suited to the needs of a circular economy: the fern/cyanobacterium symbioses from the genus Azolla. Azolla ferns fix both CO2 and N2 and grow at high rates yielding 40 t dry weight per ha year. Their use as a bio-fertilizer is ancient yet they were never domesticated, possibly because they are not seed plants: the life cycle of Azolla ferns begins on the sporophyte afloat on the water surface with the production of micro- and megasporocarps which are then shed. In the ditch sediment, the flagellate male gametes released from the glochidia fertilize the egg cells in the archaegonia of the megaspore prothallus initiating sporeling development until it again is found drifting at the surface.

The life cycle of the floating fern Azolla filiculoides

We established cryopreservation and spore-induction protocols for reliable storage of Azolla filliculoides and its cyanosymbiont. We currently investigate the induction of the sexual reproduction in this heterosporous fern with the aim to control dissemination in all Azolla species.

Our recent publications explore diverse subjects related to Azolla domestication: sexual reproduction (Brouwer et al., 2014), productivity and independence from N2 fertilizer (Brouwer et al., 2017), suitability of Azolla lipids as fuels and specialty chemicals (Brouwer et al, 2015), protein yields in simple processing schemes, polyphenol content and biosynthesis pathways (Brouwer PhD Thesis 2017) and the Azolla metagenome (Dijkhuizen et al., 2018) as part of a larger effort to sequence and assemble a first fern reference genome of good quality.

We are further looking into ways to genetically modify Azolla and any help with this would be greatly appreciated to open up Azolla as a model system for research on questions related to

1) the evolution of the fern lineage, a sister lineage to seed plants with some 12 k species,

2) the symbiotic cross-talk with Nostoc cyanobacteria that permit such a high dinitrogen fixing rates and productivity of Azolla fern species,

3) molecular breeding and agro-system development.


The Azolla Project in Utrecht has enjoyed the help from many collaborators in the Netherlands and abroad. We thank in particular:

Dr. Klaas G. Nierop (Utrecht University, Netherlands); Dr. Adrie van der Werf (Wageningen Research, Netherlands); Prof. Fons Smolders (B-WARE/Radboud University, Netherlands); Dr. Henk Bolhuis (Royal Netherlands Institute for Sea Research-NIOZ, The Netherlands); Prof. Andrea Bräutigam (Bielefeld University, Germany); Prof. Andreas Weber (Heinrich Heine University Düsseldorf, Germany); Prof. Kathleen Pryer (Duke University, USA); Dr. Fay-Wei Li (Boyce Thompson Institute, USA; Dr. Josh P. Der (California State University Fullerton, USA).