MICROBIAL-PRODUCTION OF BIOSURFACTANTS

Biosurfactants are those chemicals which an produced by microorganisms but which have both clearly defined hydrophilic and hydrophobic group s. They occur in nature in bacteria, yeasts, and fungi, and in particu lar in bacteria which grow on a water-immiscible substrate, using it a s a food source. By evolution these bacteria have adapted themselves t o feeding on these substrates by manufacturing and using a surface act ive product that helps the bacteria to adsorb, emulsify, wet, or dispe rse or solubilise the water immiscible material. The four main types o f biosurfactant are: (1) glycolipids, (2) phospholipids, (3) lipoprote ins or lipopeptides, (4) polymeric. By growth of the bacterium Pseudom onas fluorescens (NCIMB 11712) on virgin olive oil, production of a gl ycolipid in the form of a rhamnolipid is thought to have taken place. This biosurfactant group is based on the rhamnose structure, which is a methyl pentose monosaccharide. However, rhamnolipids can also be bas ed on the disaccharide by condensing two moles of rhamnose together. T he link to the hydrophobic group is by way of an acetal group; however , the 'lipid' part of the molecule contains ester and carboxyl groups. Biosurfactants over the years have found a great many uses in industr y, for example, (1) oil recovery, (2) oil spill clean-up, (3) textiles , (4) pharmaceuticals, (5) cosmetics. By this programme of research, i t is proposed to produce a biosurfactant for use in the detergents/cle aning materials industries - with the specific aim being to produce a biosurfactant which could be used in place of chemical surfactants in a detergent formulation for use in the household. Copyright (C) 1996 E lsevier Science B.V.