Cultures of Chlorella vulgaris were grown in fully transparent polyethylene bottles 20L and exposed to different light colors (i.e.; yellow, green, blue, red and white) by covering the growth vessel with fully transparency colored Nylon sheets with fixed light quantity (120µ.e), growth containers provide the desired light. Growth was performed with fully recommended media of BG-11. By the end of growth period (17 days), oils were also determined. Growth parameters including dry weight, total chlorophyll and carotenes were daily assessed. Growth parameters were varied due to the used containers color type. Yellow and white colors enhanced dry weight accumulation, despite inhibited chlorophyll accumulation. Maximum chlorophyll content was obtained by green light grown cultures followed by blue and red lights. Carotenes were increased with all used colored light, but green light represented the lowest increase as compared with control culture at zero time. Concerning dry weight growth evaluation, maximum growth rate (µmax.) was found to be the highest with cultures exposed to yellow color followed by white color. On the contrast, a negative relationship was observed with cultures that exposed to red light. As for total chlorophyll, slight differences were observed. Regarding carotenes, green and red colors represented the lowest, while white, yellow and blue colors had a little difference. The oil content was found to be slightly associated with carotenoids. White color container represented the maximum oil content following by the blue and yellow color. Oil content was closely related to carotenes content and maximum oil content was observed with yellow light grown alga (12.7%), followed by 10.02% of blue light comparing with 9.4% of white light (control) and 9.34% of red light. The lowest oil content was observed with green light that gave 8.22%.
Key words: Chlorella vulgaris Light color Dry weight Total chlorophyll Carotenoids Oil content
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