Attachment of Vibrio cholerae under various environmental conditions and to selected substrates

Abstract

Attachment rates of Vibrio cholerae (three tox+ strains of serotype 01 and two non-01's) were examined using epifluorescent microscopy and TEM. The effects of temperature, pH, various ions and nutrient starvation on attachment were determined. Optimum attachment occurred at 35°C, pH 2, concentrations of 1.0–1.5% NaCl, 1.0–1.5% KCl, 0.5–0.1% MgCl2 (with 1.0% NaCl), and 1.0–0.5% CaCl2 (with 1.0% NaCl). After one day of starvation, attachment declined by 75% with little change during further starvation. Adhesion to a variety of non-living substrates, more than 25 species of algae, and three species of aquatic plants was examined using direct fluorescent staining, fluorescent monoclonal antibody and epifluorescent microscopy. Attachment was expressed numerically as an adhesion index. The highest rate of attachment to natural substrates occurred with (some forms of) chitin and diatomaceous earth. Highest rates on algae were noted on three species of green algae, one species of red and one species of yellow green. Since V. cholerae can readily attach to many substrates common in tropic and semi-tropical estuarine waters and under conditions typical of estuarine and marine waters, this is consistent with the hypothesis that the estuarine environment is an ideal reservoir for cholera-causing strains of V. cholerae.