Antibacterial and antifungal activities of selected microalgae and cyanobacteria

Abstract

In vitro activity of nine cyanobacterial and ten microalgal newly isolated or culture collection strains against eight significant food-borne pathogens has been evaluated and compared. Water extracts and culture liquids of Gloeocapsa sp. and Synechocystis sp. demonstrated the widest spectrum of activity with minimal inhibitory concentration (MIC) ranging from 1.56 to 12.5 mg mL À1 . Culture liquid of Anabaena sp. had the highest activity (MIC = 0.39 mg mL À1 ) but only to Gram-positive bacteria. Ethanol extracts and fatty acids from all cyanobacteria and microalgae were active against Streptococcus pyogenes and/or Staphylococcus aureus. The fatty acids of Synechocystis sp. inhibited the growth of Bacillus cereus, Escherichia coli and Candida albicans (MIC values of 2.5-1.25 mg mL À1 , respectively). Exopolysaccharides (EPS) of Gloeocapsa sp. were the sample that exhibited activity against all test pathogens with lowest MIC values (0.125-1 mg mL À1 ). High activity with a narrower range of susceptible targets demonstrated the exopolysaccharides of Synechocystis sp. and Rhodella reticulata. Antimicrobial activity was proven for phycobiliproteins isolated from Synechocystis sp., Arthrospira fusiformis, Porphyridium aerugineum and Porphyridium cruentum, respectively. In conclusion Gloeocapsa sp. and Synechocystis sp. and especially their exopolysaccharides showed the most promising potential against the examined food pathogens.In vitro antimicrobial activity of microalgae H. Najdenski et al. ResultsSamples of all investigated cyanobacterial and microalgal strains were initially evaluated for antimicrobial activity by agar diffusion test. No biological activity of In vitro antimicrobial activity of microalgae H. Najdenski et al. 1539 In vitro antimicrobial activity of microalgae H. Najdenski et al.

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“…This showed that the methanol extracts have significant antifungal activity. Najdenski et al (2013) The presence of antimicrobial activity is affected by both algal species and the solvents use for their extraction (Radhika, Veerabahu, & Priya, 2012). The antimicrobial activity of algae extracts is generally assayed using various organic solvents which always provide a higher efficiency in extracting compounds for antimicrobial activity (Tüney, Çadirci, Unal, & Sukatar, 2006).…”

Bioactive Compounds Derived from Microalgae Showing Antimicrobial Activities

“…The associated increase in fungal infections prompted search for newer and safer agents to combat fungal infections [32] and a few noteworthy results encompassing microalgae are listed in Table 3 [19,24,33].…”

“…The development in the field of algal therapeutic research has made it possible by their bioactive compounds which have been found effective against most of the pathogens (Figures 1 and 2). The list of some of the algal bioactive compounds is summarized in the Table 1 [ [19][20][21][22][23][24].…”

Мicroscopic investigations (LM, TEM and SEM) and identification ofChlorellaisolate R-06/2 from extreme habitat in Bulgaria with a strong biological activity and resistance to environmental stress factors

“…Its fatty acids also had a potential activity against these cells. [1,3,4] These interesting results raised the question about the strain identification, additional to the general knowledge that it belongs to the unicellular green autosporic genus Chlorella Beijerinck. The simple morphology of this genus causes taxonomical difficulties, discussed by many authors for a very long time.…”