title: Trophic regulation of Vibrio cholerae in coastal marine waters.
abstract: Cholera disease, caused by the bacterium Vibrio cholerae, afflicts hundreds of thousands worldwide each year. Endemic to aquatic environments, V. cholerae's proliferation and dynamics in marine systems are not well understood. Here, we show that under a variety of coastal seawater conditions V. cholerae remained primarily in a free-living state as opposed to attaching to particles. Growth rates of free-living V. cholerae (micro: 0.6-2.9 day(-1)) were high (similar to reported values for the bacterial assemblages; 0.3-2.5 day(-1)) particularly in phytoplankton bloom waters. However, these populations were subject to heavy grazing-mortality by protozoan predators. Thus, grazing-mortality counterbalanced growth, keeping V. cholerae populations in check. Net population gains were observed under particularly intense bloom conditions when V. cholerae proliferated, overcoming grazing pressure terms in part via rapid growth (> 4 doublings day(-1)). Our results show V. cholerae is subject to protozoan control and capable of utilizing multiple proliferation pathways in the marine environment. These findings suggest food web effects play a significant role controlling this pathogen's proliferation in coastal waters and should be considered in predictive models of disease risk.
authors.affiliation: Marine Biology Research Division, Scripps Institution of Oceanography, University of California San Diego, La Jolla, 92093-0202, USA. aworden@rsmas.miami.edu
authors.forename: Alexandra Z
authors.initials: AZ
authors.lastname: Worden
authors.forename: Michael
authors.initials: M
authors.lastname: Seidel
authors.forename: Steven
authors.initials: S
authors.lastname: Smriga
authors.forename: Arne
authors.initials: A
authors.lastname: Wick
authors.forename: Francesca
authors.initials: F
authors.lastname: Malfatti
authors.forename: Douglas
authors.initials: D
authors.lastname: Bartlett
authors.forename: Farooq
authors.initials: F
authors.lastname: Azam
mesh_terms: D000818:Animals; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D017753:Ecosystem; D056890:Eukaryota / Q000502:physiology; D005068:Eutrophication / Q000502:physiology; D005247:Feeding Behavior / Q000502:physiology; D020387:Food Chain; D008856:Microscopy, Fluorescence; D008962:Models, Theoretical; D011157:Population Dynamics; D012623:Seawater / Q000032:analysis / Q000382:microbiology*; D014734:Vibrio cholerae / Q000254:growth & development*
chemical_list: D002734:Chlorophyll; D000077194:Chlorophyll A