Are microbial biosurfactants actually only surfactants?

The term biosurfactants refers to a complex mixture of metabolites with surface-active properties produced by specific microorganisms. However, nowadays trends moves towards isolation, screening and purifying single biocompatible, biodegradable biosurfactants with high commercialisation potential. Current legislation limiting petrochemicals combined with environmentally concerned consumers did not only stimulate research and development but it also promoted large-scale production of this class of molecules. However, recent data recorded on single congeners question the actual pertinence of using the word ‘biosurfactant’ associated to these molecules. By evaluating the accepted characteristics of surfactants and comparing them to the actual self-assembly and bulk properties in water of molecules traditionally called ‘biosurfactants’, this opinion article aims at showing that the term ‘biosurfactant’ can be somewhat reductive when applied to specific individual compounds produced by fermentation. The use of a more generic term, like bioamphiphile could probably be more pertinent and appropriate for consideration in the future.