Abstract

The aim of this study was to determine elemental constituent of microalgal biomass Spirulina platensis LEB-18 grown on the shores of Mangueira Lagoon, South of Brazil. The spread of inoculum was performed in standard Zarrouk medium. When the microalgae concentration reached 0.50 g L^-1, the biomass was separated by filtration and dried in a tray dryer at 50°C for 5 h. The harvested biomass was then ground in a ball mill, sieved to achieve a particle size of 88 µm (~ 300 mg) in triplicate, digested with concentrated HNO₃ and diluted with up to 5% HNO₃ for subsequent quantification. Mineral content was determined by inductively coupled plasma optical emission spectrometry with axial view and other nutrients by standard methods. Among the macro minerals, in μg g^-1 ± standard deviation, calcium (15.108±529), sodium (14.6552±485) and potassium (14.036±109) were found in the largest amount. The micro mineral present in greater quantity, in μg g^-1 ± standard deviation, was the iron (956±9) and nutrients present in the following order: protein (58.5%), ash (12.0%), carbohydrate (7.5%), lipid (7.0%) and crude fiber (0.95%). Results were compared with the values of minerals for human consumption recommended by the Food and Drug Administration and also with the Recommended Daily Intake (RDI) of minerals by Brazilian Legislation. The findings proved promising for the use of S. platensis strain LEB-18 as an alternative source of essential minerals and other nutrients for the human body.

Key words: Cyanobacterium, chemical element, nutritional importance, optical emission spectrometry.