The effect of indomethacin on the growth and metabolism of green alga Chlorella vulgaris Beijerinck

The aim of the present work was to study the effect of indomethacin (IM), a pleiotropic therapeutic substance commonly used in animal systems, at concentration range of 10(-8) to 10(-3) M on the growth and metabolism of single-celled Chlorella vulgaris (Chlorophyceae). Because of the presence of the indole ring in its molecule, IM is characterized by structural similarity with natural auxins, e.g. IAA. It was found that IM influenced algal growth, macromolecular synthesis and metabolism in dose-dependent manner. IM had the highest stimulating effect on algae at 10(-7) M on the 5th day of culture resulting in the increase in cell number and dry mass, DNA, RNA, proteins, phosphates, monosaccharides, photosynthetic pigments and glycolic acid content as well as protein extracellular secretion to the environment. Specific proteins from the region 20-139 kDa appeared during 10(-7) M IM treatment on the 5th day of cultivation as analysed by SDS-PAGE. IM-induced photosynthetic oxygen exchange in green alga was also noted. In contrast, the treatment with IM at the highest concentration of 10(-3) M suppressed cell division, dry mass production and decreased the level of the analysed parameters during the whole 7-day period of cultivation. Therefore, it could be speculated that IM functioned as a plant growth regulator affecting cell division and metabolism of green alga C. vulgaris.