Fatty acids of Cladophora glomerata and Chaetomorpha vieillardii (Cladophoraceae) of different niches inhibit the pathogenic microbial growth

This study aims at investigating the use of fatty acid constituents from two abundant algal species: the marine Chaetomorpha vieillardii (Kützing) M.J.Wynne 2011 and the freshwater Cladophora glomerata (Linnaeus) Kützing 1843 as natural antimicrobial agents. Water samples and massive growth of Egyptian species C. vieillardii and C. glomerata, causing environmental problems, were collected from Port Said and Ras El-Bar, respectively. After hexane extraction, the fatty acids were investigated for the bioactivity against seven pathogens; three Gramnegative bacteria: Klebsiella pneumoniae, Escherichia coli, and Pseudomonas aeruginosa, and four fungi: Aspergillus niger, Alternaria alternata, Candida albicans, and Penicillium chrysogenum. Generally, the antimicrobial activity of C. vieillardii was stronger than that of C. glomerata. However, C. vieillardii extract was inefficient against P. aeruginosa and C. albicans whereas C. glomerata extract was inefficient against E. coli and P. chrysogenum. Transmission electron microscopy (TEM) of C. vieillardii extract-treated pathogens revealed distortion of cell shape and size of K. pneumoniae and membrane disorganization, cytoplasm disintegration, and vacuolation in Aspergillus niger. The results concluded that the fatty acids of blooming algal species, C. vieillardii and C. glomerata, can be manipulated as economic and safe antimicrobial agents.