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Growing Azolla to produce sustainable protein feed: the effect of differing species and CO 2 concentrations on biomass productivity and chemical composition
Author(s) -
Brouwer Paul,
Schluepmann Henriette,
Nierop Klaas GJ,
Elderson Janneke,
Bijl Peter K,
van der Meer Ingrid,
de Visser Willem,
Reichart GertJan,
Smeekens Sjef,
van der Werf Adrie
Publication year - 2018
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.9016
Subject(s) - azolla , biomass (ecology) , productivity , dry weight , nitrogen fixation , biology , agronomy , botany , nitrogen , chemistry , organic chemistry , economics , macroeconomics
BACKGROUND Since available arable land is limited and nitrogen fertilizers pollute the environment, cropping systems ought to be developed that do not rely on them. Here we investigate the rapidly growing, N 2 ‐fixing Azolla / Nostoc symbiosis for its potential productivity and chemical composition to determine its potential as protein feed. RESULTS In a small production system, cultures of Azolla pinnata and Azolla filiculoides were continuously harvested for over 100 days, yielding an average productivity of 90.0–97.2 kg dry weight (DW) ha −1 d −1 . Under ambient CO 2 levels, N 2 fixation by the fern's cyanobacterial symbionts accounted for all nitrogen in the biomass. Proteins made up 176–208 g kg −1 DW (4.9 × total nitrogen), depending on species and CO 2 treatment, and contained more essential amino acids than protein from soybean. Elevated atmospheric CO 2 concentrations (800 ppm) significantly boosted biomass production by 36–47%, without decreasing protein content. Choice of species and CO 2 concentrations further affected the biomass content of lipids (79–100 g kg −1 DW) and (poly)phenols (21–69 g kg −1 DW). CONCLUSIONS By continuous harvesting, high protein yields can be obtained from Azolla cultures, without the need for nitrogen fertilization. High levels of (poly)phenols likely contribute to limitations in the inclusion rate of Azolla in animal diets and need further investigation. © 2018 The Authors. Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.