Antimicrobial activity of partially purified polysaccharide extract of Arthrospira platensis PCST5.

Arthrospira platensis (Spirulina) is one of the highly valuable cyanobacteria in the food and pharmaceutical industries. The intracellular and extracellular polysaccharide (PS) extracts of A. platensis have been exhibited different biological functions. Here, the antibacterial and antifungal activity of PS extract from Arthrospira platensis PCST5 was studied. Arthrospira platensis PCST5 was cultured in Zarouk medium for 25 days. Then, the polysaccharide content of biomass and excreted metabolites was extracted. The antibacterial and antifungal activity of samples was assessed. The yield of PS extraction was around 8.5% and 11.5% from biomass and excreted metabolites, respectively. The most potent antibacterial activity was for sulfuric acid-treated insoluble polysaccharide fraction, against Staphylococcus aureus (MIC = 4.25 µg ml-1). In addition, the highest antifungal activity was observed for crude excreted metabolites against Aspergillus niger (MIC = 15.625 µg ml-1) and for PS extract and sulfuric acid treated insoluble polysaccharide fraction against Candida albicans (MIC = 15.625 and 0.531 µg ml-1, respectively). This antimicrobial activity of polysaccharide extract against S. aureus can be valued in the development of topical products for wound healing. Further studies should be performed to determine the exact structure of active component and to evaluate other potential pharmacological activities in this regard.