Genomic and Phenotypic Diversity of Coastal Vibrio cholerae Strains Is Linked to Environmental Factors

Abstract

Studies of Vibrio cholerae diversity have focused primarily on pathogenic isolates of the O1 and O139 serotypes. However, autochthonous environmental isolates of this species routinely display more extensive genetic diversity than the primarily clonal pathogenic strains. In this study, genomic and metabolic profiles of 41 non-O1/O139 environmental isolates from central California coastal waters and four clinical strains are used to characterize the core genome and metabolome of V. cholerae. Comparative genome hybridization using microarrays constructed from the fully sequenced V. cholerae O1 El Tor N16961 genome identified 2,787 core genes that approximated the projected species core genome within 1.6%. Core genes are almost universally present in strains with widely different niches, suggesting that these genes are essential for persistence in diverse aquatic environments. In contrast, the dispensable genes and phenotypic traits identified in this study should provide increased fitness for certain niche environments. Environmental parameters, measured in situ during sample collection, are correlated to the presence of specific dispensable genes and metabolic capabilities, including utilization of mannose, sialic acid, citrate, and chitosan oligosaccharides. These results identify gene content and metabolic pathways that are likely selected for in certain coastal environments and may influence V. cholerae population structure in aquatic environments.

Starvation Conditions Effects on Carbohydrate Metabolism of Marine Bacteria

“…Modifications of cellular morphology should be related to modifications with carbohydrates metabolites contained in pariatal membranes for these species. Keymer et al (2007) described similar results for V.cholerae and pointed that environmental parameters, measured in situ during sample collection, should correlated to the presence of specific dispensable genes and metabolic capabilities, including utilization of mannose, sialic acid, citrate, and chitosan oligosaccharides. Thus, gene content identified and metabolic pathways that are likely selected for in certain coastal environments and may influence V. cholerae population structure in aquatic environments.…”

Phylogenetic conservatism of functional traits in microorganisms

“…In particular, traits associated with the assimilation of small organic carbon sources are highly phylogenetically dispersed. This result is consistent with observations of wide variation among the strains of E.coli, Acinetobacter, Vibrio, etc., in their ability to use particular carbon substrates (Sarma et al, 2004;Keymer et al, 2007;Vieira et al, 2011). Previous studies have identified other phylogenetically dispersed bacterial traits like nutrient acquisition (Martiny et al, 2006) and particle colonization (Hunt et al, 2008).…”

Detection and Transformation of Genome Segments That Differ within a Coastal Population of Vibrio cholerae Strains

“…Isolation and characterization of the California Vibrio cholerae strains used here are described in the report by Keymer et al (27). O1 (N16961 [25], VCX-B21 [31], A1552 [60], O395 [53]) and O139 (MO3 [41]) reference strains have been described previously.…”