Indicators of spirulina biomass growth at different doses of iodine in the nutrient medium

Iodine is an essential nutritional factor in the body of biological objects and affects the absorption and metabolism of nutrients. Iodine is a mandatory component of mineral and vitamin premixes and mineral mixtures used in livestock and poultry feeding. In the production of premixes and mixtures, iodine is mainly used in the form of potassium iodide. The use of potassium iodide in premixes for feeding hydrobionts (shrimps, crayfish) has a number of disadvantages, including the rapid dissolution of the compound in water. As a result, aquatic organisms do not receive iodine in the required amount. Spirulina platensis is able to accumulate trace elements in its cells. Using these properties, it is possible to obtain spirulina biomass as a feed additive enriched with iodine. The aim of the study was to investigate the effect of different doses of Iodine in the form of potassium iodide modified in skim milk on the change in the optical density of the nutrient medium, which characterises the growth of biomass of the blue-green algae. Five groups were formed for the experiment. In the control group, potassium iodide was added to the culture medium, which provided an additional addition of Iodine in the amount of 1.0 mg/dm3 Iodine. The nutrient medium from experimental groups I, II, III and IV was supplemented with 1.0, 2.0, 4.0 and 6.0 mg/dm3 of Iodine in the form of potassium iodide modified in skim milk. Spirulina was cultivated in the nutrient medium with different doses of Iodine for 10 days. The optical density and iodine content were determined in the nutrient medium. It has been experimentally established that the intensity of blue-green algae cell growth (as measured by optical density) depended on the content of Iodine in the nutrient medium. The highest index of optical density of the nutrient medium with spirulina at the end of the experiment was found in the experimental group where 4.0 mg/dm3 of iodine was added to the latter. It was found that the use of modified potassium iodide in skimmed milk resulted in a 10.3 % reduction in iodine loss from the nutrient medium compared to unmodified potassium iodide.