Diverse Aquatic Animal Matrices Play a Key Role in Survival and Potential Virulence of Non-O1/O139 Vibrio cholerae Isolates

Abstract

Vibrio cholerae can cause pandemic cholera in humans. The waterborne bacterium is frequently isolated from aquatic products worldwide. However, current literature on the impact of aquatic product matrices on the survival and pathogenicity of cholerae is rare. In this study, the growth of eleven non-O1/0O139 V. cholerae isolates recovered from eight species of commonly consumed fish and shellfish was for the first time determined in the eight aquatic animal matrices, most of which highly increased the bacterial biomass when compared with routine trypsin soybean broth (TSB) medium. Secretomes of the V. cholerae isolates (draft genome size: 3,852,021-4,144,013 bp) were determined using two-dimensional gel electrophoresis (2DE-GE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) techniques. Comparative secretomic analyses revealed 74 differential extracellular proteins, including several virulence- and resistance-associated proteins secreted by the V. cholerae isolates when grown in the eight matrices. Meanwhile, a total of 8,119 intracellular proteins were identified, including 83 virulence- and 8 resistance-associated proteins, of which 61 virulence-associated proteins were absent from proteomes of these isolates when grown in the TSB medium. Additionally, comparative genomic and proteomic analyses also revealed several strain-specific proteins with unknown functions in the V. cholerae isolates. Taken, the results in this study demonstrate that distinct secretomes and proteomes induced by the aquatic animal matrices facilitate V. cholerae resistance in the edible aquatic animals and enhance the pathogenicity of the leading waterborne pathogen worldwide.

Keywords: V. cholerae; aquatic product matrix; genome; proteome; resistance; secretome; virulence.

Figure 1

Genome circular maps of the eleven V. cholerae isolates. (A,B) The larger and smaller chromosomes of the V. cholerae genomes, respectively. V. cholerae MS6 was used as a reference genome (GenBank accession number: NZ_AP014524.1). Circles from the inward to outside represented GC-skew (values more than zero in purple and less than zero in green), GC content, predicted protein-coding genes of the reference genome, and eleven V. cholerae genomes, respectively.

Figure 2

Venn diagram of the identified core and strain-specific genes of the 11 V. cholerae genomes.

Figure 3

Leaching rate and initial pH values of the 8 types of aquatic product matrices. (A) Leaching rate. (B) Initial pH. Values were means ± S.D. of three parallel measurements.

Figure 4

Carbohydrate, protein, and fat contents of the 8 types of aquatic product matrices. (A) Carbohydrate content. (B) Protein content. (C) Fat content. Values were means ± S.D. of three parallel measurements.

Figure 5

Survival of the 11 V. cholerae isolates incubated in diverse aquatic product matrices and TSB medium at 37°C. (A–K) V. cholerae b9-50, B1-31, B8-16, J9-62, L10-6, N3-6, N4-21, N8-56, N8-88, Q6-10, and Q10-54 isolates, respectively.

Figure 6

Secretomic profiles of the 11 V. cholerae isolates incubated in diverse aquatic product matrices and TSB medium at 37°C. (A–K) V. cholerae B1-31, B8-16, J9-62, L10-6, Q6-10, Q10-54, b9-50, N3-6, N4-21, N8-56, and N8-88 isolates were grown in the TSB medium at 37°C, respectively. (A2–K2) The V. cholerae isolates were grown in P. pekinensis, C. auratus, A. nobilis, C. idellus, M. antiquata, P. undulata, P. viridis, and M. quadrangularis Deshayes matrix media at 37°C, respectively.

Figure 7

Gene functional classification of differential extracellular proteins secreted by the V. cholerae isolates.