The effect of certain environmental factors on growth and β-carotene production by dunaliella sp. isolated from the Dead Sea

الملخص EN

Microalga Dunaliella sp.

was isolated and identified from ponds of the south-east shores of the Dead Sea.

The most suitable media for the isolated Dunaliella sp.

was found to be M1 (modified BG-11) which gave the highest growth and β-carotene production.

The effects of different physical (temperature and light intensity) and chemical (different nitrogenous and sulfate compounds) factors were tested.

The best salinity for Dunaliella growth was 2.5 % NaCl, while the maximum β-carotene to chlorophyll a (Chl.

a) ratio was found in high salinities : Dead Sea water-M1 (DSw-M1) dilution (1 : 1), 10 % NaCl and DSw-M1 (3 : 1).

By using NaNO3 at 40 mg N l-1 concentration as a nitrogen source and MgSO4 at 25 mg l-1 concentration as a sulfate source, the maximum growth and β-carotene production was obtained.

In response to different light intensities, the maximum growth was obtained at 61 μmol s-1 m-2, and the maximum β-carotene production was at 200 μmol s-1 m-2, while the maximum β-carotene to chlorophyll a ratio was recorded in cells grown at 1000 μmol s-1 m-2.