INFLUENCE OF SURFACTANTS ON MICROBIAL-DEGRADATION OF ORGANIC-COMPOUNDS

Surfactants have the ability to increase aqueous concentrations of poo rly soluble compounds and interfacial areas between immiscible fluids, thus potentially improving the accessibility of these substrates to m icroorganisms. However, both enhancements and inhibitions of biodegrad ation of organic compounds in the presence of surfactants have been re ported. The mechanisms behind these phenomena are not well understood. To better understand the factors involved and the current state of kn owledge in this field, a search of the literature concerning the influ ence of commercial surfactants and biosurfactants on microbial metabol ism has been conducted. Factors pertaining to surfactant-substrate int eractions such as emulsification, solubilization, and partitioning of hydrocarbons between phases, all of which can influence accessibility of substrates to microorganisms, are of concern. Also, due to the dire ct interaction of surfactants with microorganisms, it appears that ste ric or conformational compatibility of surfactants with cell membrane lipids and enzymes is an important metabolic factor. Weaknesses in the general data base are evident, such as the lack of research involving Gram-positive organisms and ionic surfactants. It is also worthy to n ote that research involving commercial surfactants and mixed microbial cultures has shown a correlation between inhibited biodegradation of hydrocarbons and surfactant concentrations above the critical micelle concentration. This is a significant point of interest when remedial e fforts involving indigenous organisms in natural environments are bein g considered.