Biosurfactants for soil biology

Biosurfactants are microbially produced surface active agents with applications in soil bioremediation particularly in removing hydrocarbon and heavy metal contaminants from soil. Use of biosurfactants enhances the solubilisation, removal, bioavailability and biodegradation of hydrocarbons in soil. Biosurfactants solubilise hydrocarbons into the aqueous phase of soil where they can be either removed by soil washing or biodegraded by microbes. Various aliphatic, aromatic, polycyclic aromatic hydrocarbons and petrochemical mixtures can be effectively removed by biosurfactants. Use of biosurfactants enhances the solubilisation and removal of heavy metals from soil. Anionic biosurfactants form ionic bonds with cationic heavy metals increasing their solubility into the aqueous phase of soil where they can be removed by soil washing. Cadmium, lead, arsenic, zinc, copper and nickel can be effectively removed by biosurfactants. Although rhamnolipids are the most common biosurfactants used for soil bioremediation, others such as surfactin, sophorolipids, and bioemulsans are also useful.