The effects of some stress factors on glycerol, pigment and protein amounts of Chlorella vulgaris

In this study, the effects of various environmental factors on growth of C. vulgaris, total amount of protein, amount of glycerol, amount of astaxanthin and chlorophyll content were investigated. Environmental factors in this study can be listed as wavelength of light (blue, green, red and white light), pH, nitrogen source, nitrogen concentration, and phosphate concentration. In the samples cultured in light sources, growth of C. vulgaris was found to be highest in red light, the maximum amount of astaxanthin in blue light, and the chlorophyll amount in green light. In cultures that are inoculated into the media prepared at various pHs; it was determined that C. vulgaris's growth and glycerol amount reached the highest values at pH 10 and total protein amount at pH 4. Additionally, chlorophyll a and b were found to reach the maximum values at pH 7, while the amount of astaxanthin at acidic pHs (pH 4,6). It was observed that the cellular development of C. vulgaris reached the highest value in the culture medium prepared with NH4NO3 in which the culture media prepared by the addition of determined nitrogen sources while removing off all other nitrogen sources from the environment. Total protein and glycerol levels were determined to be maximum in the cultures where NH4NO3 was used as a nitrogen source. In the cultures where the nitrogen source was NaNO3, the amount of pigments (chlorophyll a, b and astaxanthin) found to be the highest. Furthermore, in culture medium prepared with various concentrations of NH4NO3 as a nitrogen source, it was determined that C. vulgaris's growth along with its total protein amount were at maximum level at 1.5 g/L concentration followed by the control group. In the pigment analysis, chlorophyll a, b and astaxanthin levels were found to be highest in cultures with 0.3 g / L nitrogen concentration. In all analyzes performed in C. vulgaris cultures prepared using different phosphate concentrations, maximum values were obtained in all the variables studied in the culture medium prepared with 0.01 g/L phosphate concentration, followed by the positive control group. Limited to the factors examined, it is one of the important findings of this study that phosphate stress on C. vulgaris is not as effective as nitrogen stress.