BIOCHEMICAL CHARACTERISTICS OF A NEWLY ISOLATED STRAIN COELASTRELLA SP. BGV CULTIVATED AT DIFFERENT TEMPERATURES AND LIGHT INTENSITIES
PETYA DIMITROVA, GERGANA MARINOVA*, SVETOSLAV ALEXANDROV, IVAN ILIEV, PLAMEN PILARSKI
Institute of Plant Physiology and Genetics – Bulgarian Academy of Sciences.Acad. G. Bonchev str. Bl.21, Sofia, Bulgaria
*Corresponding author:gergana_gacheva@abv.bg
Keywords: Coelastrella, cultivation, temperature, light intensity, metabolites
Abstract: The adaptive capacity of microalgae to varying temperature is of key importance for their mass outdoor cultivation because daily and seasonal temperature fluctuations are significant. Our aim was to study the influence of temperature and light intensity on the growth and cellular metabolites of a newly isolated Coelastrella sp. strain BGV. The alga was cultivated at wide temperature range (20 – 44ºC) and two light intensities (unilateral – 8000 lux and bilateral illumination – 2 x 8000 lux). Optimal temperature for algal growth was 25ºC and 35ºC at low and high light intensity, respectively. Regardless of the illumination, the extreme temperatures (40, 42 and 44ºC) were a stress factor and led to algal growth retardation. Coelastrella sp. BGV required lower light intensity for biomass accumulation (7.7 g.l-1 dry weight at 25ºC) and temperatures above 35ºC for enhanced protein synthesis. Carbohydrates reached their maximum at 30ºC – 50.7% and 45.7% of DW. Lipids were the most affected by the temperature and light intensity metabolites. They varied from 7.3% to 40% of DW at unilateral illumination and from 10,3% to 37% for bilateral illumination. According to gas-chromatographic analysis the main fatty acids were myristic (14:0), palmitic (16:0), stearic (18:0), oleic (18:1), linoleic (18:2), alpha-linolenic (α-18:3) and their proportion clearly varied according to different growth conditions. Carotenoid production increased with the raising of temperature. Coelastrella sp. BGV showed high productivity and preserved good qualitative composition of the biomass in the range 20-35оС. The strain could be recommended as a promising for intensive mass outdoor cultivation.