Research Article: Effect of antimicrobial nanocomposites on Vibrio cholerae lifestyles: Pellicle biofilm, planktonic and surface-attached biofilm

Date Published: June 12, 2019

Publisher: Public Library of Science

Author(s): Anaid Meza-Villezcas, Ana L. Gallego-Hernández, Fitnat H. Yildiz, Oscar E. Jaime-Acuña, Oscar Raymond-Herrera, Alejandro Huerta-Saquero, Amitava Mukherjee.


Vibrio cholerae is an important human pathogen causing intestinal disease with a high incidence in developing countries. V. cholerae can switch between planktonic and biofilm lifestyles. Biofilm formation is determinant for transmission, virulence and antibiotic resistance. Due to the enhanced antibiotic resistance observed by bacterial pathogens, antimicrobial nanomaterials have been used to combat infections by stopping bacterial growth and preventing biofilm formation. In this study, the effect of the nanocomposites zeolite-embedded silver (Ag), copper (Cu), or zinc (Zn) nanoparticles (NPs) was evaluated in V. cholerae planktonic cells, and in two biofilm states: pellicle biofilm (PB), formed between air-liquid interphase, and surface-attached biofilm (SB), formed at solid-liquid interfaces. Each nanocomposite type had a distinctive antimicrobial effect altering each V. cholerae lifestyles differently. The ZEO-AgNPs nanocomposite inhibited PB formation at 4 μg/ml, and prevented SB formation and eliminated planktonic cells at 8 μg/ml. In contrast, the nanocomposites ZEO-CuNPs and ZEO-ZnNPs affect V. cholerae viability but did not completely avoid bacterial growth. At transcriptional level, depending on the nanoparticles and biofilm type, nanocomposites modified the relative expression of the vpsL, rbmA and bap1, genes involved in biofilm formation. Furthermore, the relative abundance of the outer membrane proteins OmpT, OmpU, OmpA and OmpW also differs among treatments in PB and SB. This work provides a basis for further study of the nanomaterials effect at structural, genetic and proteomic levels to understand the response mechanisms of V. cholerae against metallic nanoparticles.

Partial Text

Vibrio cholerae pathogenic strains are the etiologic agent of cholera, an acute watery diarrheal disease that occurs in 3–5 millions of persons annually, with 100,000 to 120,000 lethal cases [1,2]. V. cholerae can switch between planktonic and biofilm lifestyles. Biofilms are microbial communities, composed of microorganisms and extracellular matrix [3]. Biofilm formation enhances growth, survival, and persistence of Vibrio species in the aquatic ecosystem, and also increase its antibiotic resistance [4,5]. In the human host, biofilms play a role in the disease process, with a higher infectivity than planktonic cells [6,7].

Biofilms tolerance has become a serious clinical concern due to their formidable resistance to conventional antibiotics and prevalent virulence. For this reason, there is a need to develop alternative antimicrobial agents to eradicate biofilms and prevent their formation. Metallic nanoparticles have been recently found to be a promising cure for microbial infection with a low chance of developing bacterial resistance.