Microorganisms produce biosurfactants as a way to compete in their environment. Secreted biosurfactants enhance solvency of hydrophobic materials and permeability of cellular membranes, and allow their producers to resist external injuries. In this context, biosurfactants usually have bioactive performance and functions, including growth inhibition of other microorganisms, bio-film regulation and inhibition, as well as cytotoxic, cell lytic, antiviral, anti-adhesion, surface motility, and immune response stimulation effects.
As an antibacterial, rhamnolipids and lipopeptides have been shown to exert toxicity on Mycobacterium, Enterobacter, Serratia, Klebsiella, Micrococcus, Streptococcus, and Staphylococcus, and other species. As an anti-fungal, they directly lyse zoospores. And the MIT assay has shown that rhamnolipids and lipopeptides inhibit growth of human breast cancer cells in a does-dependent manner.