New Bacteriocins from <i>Lacticaseibacillus paracasei</i> CNCM I-5369 Adsorbed on Alginate Nanoparticles Are Very Active against <i>Escherichia coli</i>

• Main Authors: Yanath Belguesmia, Noura Hazime, Isabelle Kempf, Rabah Boukherroub, Djamel Drider
• Format: Article
• Language: English
• Published: MDPI AG 2020-11-01
• Series: International Journal of Molecular Sciences
• Subjects: new bacteriocins; alginate nanoparticles; nano-antibiotic; cytotoxicity; Gram-negative bacteria; antibacterial
• Online Access: https://www.mdpi.com/1422-0067/21/22/8654

<i>Lacticaseibacillus paracasei</i> CNCM I-5369, formerly <i>Lactobacillus paracasei</i> CNCM I-5369, produces bacteriocins that are remarkably active against Gram-negative bacteria, among which is the <i>Escherichia coli-</i>carrying <i>mcr</i>-1 gene that is involved in resistance to colistin. These bacteriocins present in the culture supernatant of the producing strain were extracted and semi-purified. The fraction containing these active bacteriocins was designated as E20. Further, E20 was loaded onto alginate nanoparticles (Alg NPs), leading to a highly active nano-antibiotics formulation named hereafter Alg NPs/E20. The amount of E20 adsorbed on the alginate nanoparticles was 12 wt.%, according to high-performance liquid chromatography (HPLC) analysis. The minimal inhibitory concentration (MIC) values obtained with E20 ranged from 250 to 2000 μg/mL, whilst those recorded for Alg NPs/E20 were comprised between 2 and 4 μg/mL, which allowed them to gain up to 500-fold in the anti-<i>E. coli</i> activity. The damages caused by E20 and/or Alg NPs/E20 on the cytology of the target bacteria were characterized by transmission electron microscopy (TEM) imaging and the quantification of intracellular proteins released following treatment of the target bacteria with these antimicrobials. Thus, loading these bacteriocins on Alg NPs appeared to improve their activity, and the resulting nano-antibiotics stand as a promising drug delivery system.