Neogi, Sucharit Basu, Islam, M. Sirajul, Nair, G. Balakrish, Yamasaki, Shinji and Lara, Rubén J. (2012) Occurrence and distribution of plankton-associated and free-living toxigenic Vibrio cholerae in a tropical estuary of a cholera endemic zone. Wetlands Ecology and Management, 20 (3). pp. 271-285. DOI

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Cholera epidemics are thought to be influenced by changes in populations of estuarine Vibrio cholerae. We investigated the abundance and distribution of this bacterium, as “free-living” (<20 μm fraction) and associated with microphytoplankton (>20 μm) or zooplankton (>60 μm), in the Karnaphuli estuary of Bangladesh during pre- and post-monsoon seasons. Cultivable Vibrio populations were ~102–104 colony forming units (CFU) ml−1 in the high saline zone (19–23 practical salinity unit, PSU) and declined in freshwater (<101 CFU ml−1). Culture independent detection of toxigenic V. cholerae O1 and O139 serogroups revealed a higher abundance of “free-living” (104–105 cells l−1) than those attached to plankton (101–103 cells l−1). However, “free-living” O1 and O139 cells were sometimes absent in the medium saline and freshwater areas (0.0–11 practical salinity unit [PSU]). In contrast, plankton samples always harbored these serogroups despite changes in salinity and other physico-chemical properties. Microphytoplankton and zooplankton were dominated by diatoms and blue-green algae, and copepods and rotifers, respectively. Toxigenic V. cholerae abundance did not correlate with plankton abundance or species but had a positive correlation with chitin in the <20 μm fraction, where suspended particulate matter (SPM), V. cholerae and chitin concentrations were highest. C:N ratios indicated that organic matter in SPM originated predominantly from plankton. The differential occurrence of “free-living” and attached V. cholerae suggests a pivotal function of plankton in V. cholerae spreading into freshwater areas. The probable association of this pathogen with organisms and particles in the nanoplankton (<20 μm) fraction requires validation of the concept of the “free living” state of V. cholerae in aquatic habitats.

Document Type: Article
Programme Area: UNSPECIFIED
Research affiliation: Ecology > Mangrove Ecology
Refereed: Yes
Open Access Journal?: No
ISSN: 0923-4861
Date Deposited: 29 Aug 2019 13:54
Last Modified: 26 Mar 2024 13:29

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