Toxins include a diverse set of bioactive compounds, including proteins, and are produced by microorganisms to establish a competitive advantage in their distinct environment and enhance survival . They can be classified based on their biological effect on the target organism, e.g. into enterotoxins, cytotoxins, neurotoxins, leukotoxins, dermonecrotic toxins, and hemolytic toxins, and based on whether they are released to target cells (exotoxins) or cell-associated (endotoxins) . Protein toxins are active at very low concentrations and can either act on the cell surface, by interfering with signal transduction, by damaging the membrane, or intracellularly, where they induce cell death, cytoskeleton alteration, or blockade of exocytosis .