Development of biochemicals-functionalization of biosurfactants and natural dyes

Under the aspect of environmental protection an increased demand for natural fine chemicals has been observed. From this viewpoint, this paper reviews current works on biodyes and attempts to describe their new functions. Biosurfactants have remarkably excellent surface active properties in spite of their bulky molecular structures, as well as good biodegradabilities and safety for living organisms. Furthermore, rhamnolipid A and B, produced by a hydrocarbon-assimilating bacterium, showed pH-sensitive conversion of molecular aggregates in the form of micelles, lipid particles, lamella, and vesicles. Curcumin derivatives were prepared to achieve a lasting color of the original dye, and the characteristics of microbial pyocyanine as a biodye were investigated. Hybrids of pyrene and biosurfactants were prepared to monitor the microenvironmental conditions of various kinds of colloidal surfaces and biointerfaces with respect to their polarity and fluidity. (C) 1997 Elsevier Science S.A.