Green synthesis of iron nanoparticles from Ulva lactuca and bactericidal activity against enteropathogens

Antimicrobial resistance has emerged as one of the major public-health issues in recent times. The multi-drug resistant opportunistic bacterial pathogens, Staphylococcus aureus, Escherichia coli, and Salmonella typhimurium cause urinary tract, respiratory infections and diarrhea. The prevalence in the hospital environment increases multi-drug resistant bacteria and beta-lactam antibiotics (carbapenems) are highly effective against these pathogens, however development of drug resistance against these antibiotics may lead to increased mortality. Hence, it is of utmost significance to develop alternative antibiotics against these drug-resistant bacteria. In this study, we have synthesized iron nanoparticles using the water extract of marine algae (Ulva lactuca) collected from Tamilnadu coast, India. The nanoparticles were characterized by UV-spectroscopy, transform infrared spectroscopy, and Scanning electron microscopy. The green synthesized nanoparticles have the size of 30–40 nm and have potent biological activities. The synthesized nanoparticles showed anticancer activity against HeLa and DLD-1 cell lines. The methanol extract of U. lactuca showed maximum activity against E. coli (24 ± 2 mm), followed by S. typhimurium (23 ± 1 mm), B. cereus (19 ± 1 mm), P. vulgaris (17 ± 2 mm), and S. aureus (16 ± 2 mm). Antibacterial disc diffusion analysis of nanoparticles showed improved activites than algal extract. The iron nanoparticles showed activity against S. aureus (24 ± 1 mm), E. coli (29 ± 1 mm), and S. typhimurium (31 ± 2 mm). The minimum inhibitory concentration values of nanoparticles against diarrhoea causing bacteria varied widely. U. lactuca extract was highly effective against S. typhimurium (25 µg/mL), followed by E. coli (30 µg/mL), and S. aureus (45 µg/mL). These results clearly demonstrate that iron nanoparticles could be developed as alternate therapeutics against carbapenems resistant bacteria and against types of cancers.