Magnesium Hydroxide Nanoparticles Kill Exponentially Growing and Persister Escherichia coli Cells by Causing Physical Damage

• Published in: Nanomaterials (Basel, Switzerland) Vol. 11; no. 6; p. 1584
• Main Authors: Nakamura, Yohei, Okita, Kaede, Kudo, Daisuke, Phuong, Dao Nguyen Duy, Iwamoto, Yoshihito, Yoshioka, Yoshie, Ariyoshi, Wataru, Yamasaki, Ryota
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 16.06.2021; MDPI
• Subjects: Antibacterial activity; Antibiotics; Caustic soda; Chloride; Damage; E coli; Environmental impact; Escherichia coli; Hygiene; Magnesium; Magnesium hydroxide; magnesium hydroxide nanoparticle; Nanoparticles; Particle size; persister; Scanning electron microscopy; Sodium; sterilization; Toxicity; United States > US; Japan
• ISSN: 2079-4991; 2079-4991
• DOI: 10.3390/nano11061584

Magnesium hydroxide nanoparticles are widely used in medicinal and hygiene products because of their low toxicity, environment-friendliness, and low cost. Here, we studied the effects of three different sizes of magnesium hydroxide nanoparticles on antibacterial activity: NM80, NM300, and NM700. NM80 (D50 = 75.2 nm) showed a higher bactericidal effect against Escherichia coli than larger nanoparticles (D50 = 328 nm (NM300) or 726 nm (NM700)). Moreover, NM80 showed a high bactericidal effect against not only exponential cells but also persister cells, which are difficult to eliminate owing to their high tolerance to antibiotics. NM80 eliminated strains in which magnesium-transport genes were knocked out and exhibited a bactericidal effect similar to that observed in the wild-type strain. The bactericidal action involved physical cell damage, as confirmed using scanning electron microscopy, which showed that E. coli cells treated with NM80 were directly injured.