Work task leader: Dr. Vince Ördög
Microalgae are ethically acceptable biodiesel raw materials because they are not used as food or feed materials. There is increasing evidence that microalgae provide practical solutions both for biodiesel production and for decreasing carbon dioxide emission. They produce a greater biomass and their biodiesel production is at least 10 to 20-times higher than oil-producing higher plants. Microalgal mass cultures can be grown under industrial conditions on land not suitable for agricultural crop production, and use less water than oil-producing plants. To date, there is no appropriate high lipid-producing microalgal strains available, as well as no routine and energetically balanced technology designed for the production of microalgae for biodiesel. Therefore, ways of productively using microalgae as a renewable energy source should be introduced into the algal mass culture technology.
In the first half-year term of the research project, algal strains potentially useful as biodiesel raw material were investigated. Chlorella strains from the Mosonmagyaróvár Algal Culture Collection were screened because of their: (1) fast growth and high biomass production; (2) changing lipid production, which can increase by as much as 50% under improved environmental conditions; (3) legal use as food and feed material.
In the report we will describe the obtained results in more detail:
1. Investigation of lipid content of algal strains depending on nitrogen supply.
Most of the investigated Chlorella strains responded with an increased lipid content when subjected to a decreased N-supply. In some cases no such relationship could be measured.
2. Investigation of lipid content of algal strains under N-limiting conditions.
The lipid content and the daily lipid production of 20 Chlorella strains were measured in samples collected from culture suspensions in the logarithmic (young) and stationary (old) growth phases. We established that the lipid content of the old cultures were higher or significantly higher than that of the young cultures.
3. Changes in the lipid content of a selected strain in synchronous culture.
The lipid content was independent from the cell cycle, unless the nitrogen was taken up from the nutrient medium by the algae.
General conclusions from the obtained results:
1. The highest lipid-producing strains are generally Chlorella minutissima. These were isolated from different places in the world.
2. Lack of nitrogen in the nutrient medium stimulated lipid production in algal cells, that is, increased their lipid content. The influence of culture age on the lipid content of the algae can be explained by the disappearance of nitrogen in the old cultures resulting in the old cultures having a higher lipid content than the young, logarithmic cultures.
3. The lack of nitrogen increased the lipid content, but decreased the biomass production of the Chlorella strains. Consequently, the daily lipid production of a given strain can be manipulated only within a narrow range by changing environmental conditions.
Realized conferences, study tours by the project: TÁMOP-4.2.2 Opening conference