Antibacterial Activity of Cyanobacteria Dolichospermum affine Isolated from Freshwater

Abstract

Cyanobacteria are known for their potential for antibacterial activity against a variety of pathogens,which are of medicinal importance in drug development. In addition, Cyanobacterial species produce various secondary metabolites that are used as dye and pigmentation and food additives.Cyanobacteria Dolichospermum affine (Lemmermann) Wacklin, L. Hoffmann & Komárek was isolated from freshwater resources and its antimicrobial effect was studied. Chloroform, methanol andwater extracts of D. affine were tested to investigate their efficiency against five pathogenic bacterial strains [Pseudomonas aeruginosa (ATCC 27853), Shigella dysenteriae (ATCC 11835), Escherichia coli (ATCC 25924), Staphylococcus aureus (ATCC 29213) and Bacillus subtilis (ATCC 6633)]. Theantimicrobial test was determined using the disk diffusion method. The antimicrobial activities ofD. affine extracts were measured using the diameter of the inhibition zone (DIZ) of the pathogenmicroorganisms. The results showed that B. subtilis and E.coli were more sensitive, while S. aureusand P. aeruginosa showed more intermediate results. The highest antimicrobial activity was measured against E. coli (DIZ=13.9±0.05 mm - methanol), followed by B. subtilis (DIZ=13.6±0.05 mm -methanol). The lowest antibacterial effect of D. affine extracts were observed against P. aeruginosa(DIZ=11.7±0.02 mm - chloroform) and S. aureus (DIZ=12.2±0.03 mm - chloroform). The Gram-negative bacteria S. dysenteria exhibited no zone of inhibition. The aqueous extract showed poor activities against the tested pathogenic bacteria. Therefore, this study revealed that D. affine extractswould be a promising natural resource for new antibiotics and further research would be needed.