Response of Anabaena cylindrica to variations in growth conditions in photo-bioreactors and its use as a biofertilizer

Abstract

Nitrogen is a vital nutrient for plant growth. Traditional methods of manufacturing nitrogen fertilizers are energy intensive and lead to the production of greenhouse gases. Nitrogen fixing cyanobacteria have shown promise as an environmentally friendly method of producing biofertilizer containing nitrogen. A potential candidate organism, Anabaena cylindrica, was assessed for adaptability to changes in growth conditions. Variations in flow regime of the air in the reactor, superficial velocity of the air entering the reactor, temperature, light cycle and intensity had little statistically effect over the ranges tested on either the average growth rate or final biomass concentration. The nitrogen content, chlorophyll and final biomass concentrations increased considerably to 74.2 ± 6.9 mg N/L, 12.3 ± 0.97 micro-g/mL and 0.81 ± 0.16 g/L, respectively, when 0.15 mM of magnesium sulfate heptahydrate and 0.005 mM of disodium ethylenediamine tetraacetate dihydrate was present in the culture medium. Magnesium is utilized within the cyanobacterial cell for many purposes. Evaluation of the growth of wheat, camelina, carrots, tomatoes and Kentucky bluegrass, when treated with cyanobacterial biofertilizer, showed statistically similar results when compared to chemically fertilized plants.