Izolacija i selekcija mikroalgi za proizvodnju ulja / The isolation and screening of microalgae for the production of oil

The biodiesel production has gained increasing attention of the researches in recent years. Current commercial biodiesel production involves transesterification of oil derived from oil crops. Since this production is no more sustainable, the use of microalgae represents a good alternative. Microalgae have high growth rate, high oil content and can be cultured in the environment which are not suitable for agriculture. Additionally, microalgae cultivation improves the reduction of carbon dioxide in the atmosphere. Selection of microalgae for oil production must take into consider certain criteria which include growth rate, oil content, fatty acids profile and ease of separation. In order to analyze the possibility of the use of mic- roalgae for the production of oil, isolation of freshwater microalgae was per- formed. The isolation was done by the use of traditional techniques from fresh- waters near Leskovac. A total number of 6 microalgae strains were isolated and identified as the representatives of the genera Chlorococcum (1 isolate), Chlorella (1 isolate), Scenedesmus (1 isolate) and Desmodesmus (3 isolates). Isolates of microalgae were screened for the growth rate, biomass and oil productivity and oil content. The highest content of biomass was 1.5 g/l and it was observed in the strains Chlorococcum sp. and Desmodesmus sp. 1. The highest value of specific growth rate was calculated during the growth of microalgae Chlorella sp., Scene- desmus sp. and Desmodesmus sp.1, while the lowest value was observed for Chlorococcum sp. Oil productivity was the highest for Chlorella sp. and Desmo- desmus sp.1 (0.4 g/l) and the lowest for Desmodesmus sp.2, Desmodesmus sp.3 and Chlorococcum sp. (0.2 g/l). The oil content was in the range from 15.8% (Chlorococcum sp.) to 33% (Chlorella sp). Since the microalgae isolates Chlorella sp. and Scenedesmus sp. had the highest oil productivity, high growth rate and high oil content, these strains are the most suitable for further investigation in order to improve the oil yield and analyse the possibility of the use in the pro- duction of biodiesel.