Cyanobacteria -
Fertilizer out of thin Air!

[Abstract - Overview]

As far as organic farming goes, nitrogen has always been a limiting factor.  In conventional farming, nitrogen fertilizer is mineral based, expensive, and created using a process that is very petroleum intensive.  For example: In order to synthesize 1 ton of pure nitrogen (including transportation and packaging) approximately 1 ton of fuel is consumed. Worldwide, each year 90 million tons of crude oil or natural gas is used for nitrogen fertilizer production, leading to 250 million tons of carbon dioxide being emitted.  1.6% of the world energy supply is used in nitrogen fertilizer production.

There are certain micro-organisms, cyanobacteria, that can bind nitrogen from the air. These bacteria, also called blue-green algae, however, are usually toxic and are very unpopular because of their tendency to cause algae blooms, in popular bodies of water. Lately, non-toxic strains of cyanobacteria are increasingly be discovered. The Institute for Limnology, Austrian Academy of Sciences, made some of these strains available to us, for our research.

We wanted to find out which of these strains  best proliferate and simultaneously fix the most atmospheric nitrogen. Additionally, we wanted a strain that was resilient, easy to handle and suitable to use in agriculture, thus potentially providing us with a valuable organic fertilizer with a very low energy demand.

Breeding was first undertaken in  laboratory conditions at the HLFS Ursprung in petri dishes. We had two rooms of a former residence available in which were able to build a lab, with suitable conditions for growing blue-green algae.Growth rates, dry matter content, cell count and absolute nitrogen enrichment in addition to optical density, temperature and light conditions were regularly measured over the following months.  Using these parameters we were able to build and continuously update our database.  What we couldn't measure ourselves was the overall nitrogen content of any given sample. Therefore, we froze 2 x week a sample from each of the colonies, which was later professionally analyzed at the Fachhochschule Wels u. AGES.

In order to grow the algae out site of the lab, we had to develop "Continuous Tube Reactors" in which the algae in would grown and harvested. Our partners at the HTL Braunau were tasked with the development of this apparatus. A powerful laboratory prototype is already running in test mode and is constantly being optimized. The initial results look promising. The technological leap from the small petri dish to technologically sophisticated continuous reactor and large-scale investment in compliance with microbiological standards -proved, until now, to be very difficult.

The obtained dry matter- (400g - 1000g/m3) or pure

nitrogen levels (100g - 300g/m 3 ) the algal substrate were at first sight too low to ensure economic feasibility. However, we could show that by simple sedimentation this value can be raised.
Unfortunately, the cyanobacteria were rather slow. We made determined in the lab that they had a doubling rate, for dry matter, of about 5 days. With the possibility of this rate being accelerated to 2 days.

For greenhouse growers, who can use a substrate additive with lower nutrient levels, the process could be added to existing systems. Rain water collecting ponds would simply need to be connected to an algae tube reactor. With little investment the algae substrate could be mixed into the existing watering system.  While this would not completely replace the need for mineral fertilizers, it would lower the amount of petroleum based fertilizer needed to grow a crop.  Creating a more environmentally friendly "hybrid" fertilizing process.

From our tests of  Cyanobacteria sample (Nostoc sp. 341, D), which is found domestically, it could be that in the greenhouse cultures of Biogärtnern may not only act as fertilizer, but also, because of the dry matter growth rates and the nitrogen bound in the form of glutamine, contribute to the formation of healthy hummus.. It would be an effective micro-organism being promoting additional CO2 fixation in the soil.

Ultimately it is still a long way from the lab to application. For a number of application problems, we already have solution ideas and optimization suggestions. We presented our project at the Agriculture Vienna and became there enthusiasm and willingness to accept the applications 'our' cyanobacteria in modern gardening.

Our green idea of  "fertilizer out of thin air" fell on fertile soil.

Ultimately it is still a long way from commercial use, outside of a lab.