Biosurfactants and Bio-Emulsifiers from Algae

The terms biosurfactant and bioemulsifier have often been used interchangeably to describe surface active biomolecules. However, it is important to note that there are marked differences between them especially based on their physico-chemical properties and physiological roles. Although bioemulsifiers and biosurfactants are both amphiphilic in nature and are produced bya wide range of microorganisms, each exhibit characteristic roles in nature. These microbial surfactants have recently received increased scientific attention due to their unique characteristics relative to chemically derived surfactants. Their unique features include; non-toxic, biodegradable, biocompatibility, efficiency at low concentrations and their synthesis from natural substrates under mild environmental conditions. The combination of polysaccharide, fatty acid and protein components in bioemulsifiers confers upon them better emulsifying potential and ability to stabilize emulsions. It is also important to note that some efficient bioemulsifiers consists of only polysaccharides and proteins. On a general note bioemulsifiers have been associated with a number of potential applications including: remediation of oil polluted water and soil; enhanced oil recovery and clean-up of oil contaminated vessels and machineries; heavy metal removal, formation of stable emulsions in food and cosmetics industries and therapeutic activities (antibacterial, antifungal, pesticidal and herbicidal agents).Solar energy in the production of polysaccharides has been generally overlooked, despite high product yields and wide variety of polysaccharide production. However, due to current market demand for alternatives to synthetic surfactants and emulsifiers, the production of polysaccharides with surface active properties is attracting the attention of researchers. Oceanic biological surface active compounds still represent a major untapped and unexplored area of research. Algal EPS represent a huge range of structures. They are high-molecular-weight structures (10-30kDa) which encompass homopolymeric and heteropolymeric compositions. EPS structure varies widely between different genera of algae and is generally considered to be related to the environmental conditions on the organism. They are gaining much attention in relation to potential bioemulsifier properties. In particular, the green micro-algae Dunaliella salina and red algae Porphyridium cruentumare receiving attention as robust EPS producers with industrial application. They are highly biodegradable and have low toxicity. There is also an abundance of raw materials for the production of these molecules and they are highly biocompatible. Biosurfactants and bioemulsifiers share many environmental advantages, over their chemically synthesised counterparts