Culture of Azolla-Anabae n a Symbiosis in a Pond and Its Use as Biomass

Abstract

The aquatic fern Azolla-Anabaena symbiosis whic h can grow without nitrogenous nutrient because of the N₂ fixing capability of Anabaena, was cultivated in a pond and its possible use as biomass was examined. The extent of growth in the pond (Komoike, Sakai) of 1200kg/100m² was less than that in a synthetic nutrient solution and in a diluted secondary efflue nt, The N₂ fixing activity of Azolla grown in the pond also decreased gradually when compared to that of the control which was grown in the synthetic nutrient solution.
A significantly higher content of dehydro-ascorbic acid (99.3 μ/gig) than that of L-ascorbic acid (O.5μ/gig) in fresh Azolla grown for 3 d, which is charac cteristic in view of possible use of Azolla as animal feed.
In the methane gas ferm entation experiment, the extent of conversion to gas increased by about 40% by the preheating Azolla-plants at 100 °C.