The evaluation of the growth performance of a cyanobacterial isolate Phormidium lucidum (Kützing ex Gomont 1892) grown under different environmental conditions and its use as a dietary source for Daphnia magna (Straus 1820)

Abstract

This study presents the effect of cyanobacterium isolated from Bolluk Lake (Konya, Türkiye) which is a saline lake on the growth performance of Daphnia magna. Isolated cyanobacteria species were identified as Phormidium lucidum according to its 16S rDNA sequences. The effects of different growth conditions including pH (7.18, 8.15, 9.17 and 10.26), light intensity (1200, 2400, 3600 and 4800 lux), temperature (10, 20, 25 and 30°C) and nitrogen concentrations (0.25, 0.5, 1.0 and 1.5 g/L) on P. lucidum was studied. Effects of each environmental factor on biochemical composition (total protein, total lipid and chlorophyll-a concentration) of P. lucidum were also studied. The optimum growth conditions were found as pH 7.18, ambient temperature 20°C, nitrogen 0.25 g/L and light intensity 3600 lux, after a 2-week incubation period. The effects of various mixtures of the cyanobacteria and Chlorella vulgaris which is a common feed for Daphniids were also evaluated for their effects on the growth rates of D. magna. The best growth rate for D. magna was obtained in the medium containing 100% P. lucidum at the end of the 13ᵗ ͪ day.