ABSTRACT

In V. cholerae, environmental signals have evolved to control toxin and pilus gene expression through a complex signal transduction cascade involving other membrane signaling proteins that are encoded by the CTX and toxin coregulated pili pathogenicity islands. The overwhelming majority of marine microbes that are naturally present in the sea are nonpathogenic for humans. Many advances in the understanding the genetic and biochemical mechanisms by which bacteria produce human diseases come from the use of cell culture, but proof of in vivo effects depends on the use of animal models. Diseases of animals that are transmitted to humans are known as zoonoses. Some fish pathogenic bacteria can infect humans, usually via skin abrasions or wounds. Besides affecting human health, harmful algal blooms damage other marine life and have significant economic and social impacts on fisheries, aquaculture, and tourism.