Interactions of Vibrio cholerae, Shigella flexneri, Enterococci, and Lactobacilli in Continuously Fed Cultures

Abstract

Growth and interactions of bacteria were studied in a continuous culture apparatus which premitted controlled observation of both pure and mixed cultures simultaneously. Under these conditions, the growth of V. cholerae was markedly suppressed, although not eliminated, by the presence of growing enterococci and lactobacilli. The suppression was due largely or entirely to the enterococci. By contrast, the growth of S. flexneri 2a was not affected by the presence of enterococci. The cause of the supression of V. cholerae is unknown. There was no evidence that it was the result of competition for nutrients or the production of antibiotics in the usual sense. Further, it was shown that embryonated chicken eggs could be protected against the lethal effect of cholera vibrio infection by pretreatment with viable enterococcus cells.