In Vitro Antimicrobial Activity of Arthrospira platensis

Abstract

Arthrospira platensis is a cyanobacteria with the ability to produce a large amount of antimicrobial substances, making it a suitable microorganism for use as a biocontrol agent for pathogenic bacteria. In this research, different amounts of A. platensis extracts grown outside (100 μg/μL, 50 μg/μL, and 25 μg/μL) were tested for their ability to kill five types of bacteria: Escherichia coli, Bacillus subtilis, Proteus vulgaris, Salmonella enterica, and Staphylococcus aureus. The tests were done using methanol, aqueous, and chloroform as solvents. The disc diffusion and serial micro-dilution techniques were used to determine the inhibition zone and minimum inhibitory concentration (MIC) of the pathogen bacteria, respectively. The results showed that A. platensis extracts significantly inhibited the growth of E. coli, with inhibition zones of 24.00 ±1.51 mm, 18.00 ± 0.15 mm and 15.00±0.12 mm at concentrations of 100 μg/μL, 50 μg/μL, and 25 μg/μL, respectively. At the highest concentration, the effect is comparable to that of tetracycline (30 μg). Methanol and aqueous extracts with MIC values of 100-200 μg/μL demonstrate antibacterial properties. However, A. platensis extracts did not significantly inhibit the growth of P. vulgaris, S. enterica, or S. aureus. In conclusion, the findings of this study demonstrated that outdoor-cultured A. platensis extracts could be a good source for the production of promising antimicrobial agents.