ABSTRACT
I. Introduction 232
II. Genetics of Surface-Active Compounds in Gram-Negatives 232 A. Acinetobacter calcoaceticus 232 B. Pseudomonads 234 C. Serratia marcescens 238
III. Genetics of Biosurfactant Production in Bacillus subtilis 239 A. Biosurfactants produced by Bacillus spp. 239 B. Identification of genetic loci responsible for surfactin production 240 c. Overproduction of surfactin by stable mutants of B. subtilis 240
IV. Molecular Genetics of Lung Surfactants 241 A. Physiological roles and composition of lung surfactant 241 B. Structure of surfactant-associated proteins 241 C. Molecular biology of surfactant protein genes 242
V. Surface Activity of Proteins and Amphiphilic a-Helices 245 A. Surface activity of proteins 245 B. Amphiphilic a-helices 246
I. INTRODUCTION Many microorganisms, both prokaryotic and eukaryotic, are able to grow on water-insoluble substrates like n-alkanes, due to alkane-specific oxidation systems, to substrate-induced alterations in their cell surfaces, and to the production of emulsifying agents, some of them acting as biosurfactants. Many of these extracellular and cell-waIl-associated compounds have the potential to promote cell attachment to hydrophobic surfaces, to emulsify water-insoluble substances, and to mediate the transport of these unconventional substrates into the cell. Thus, they are important in determining the degree of hydrophobicity that a cell achieves, the wettability of substrates, the adhesion of a cell to the SUbstrate, and the distribution of cells between oil and water. There is an increased interest in developing industrial processes in which highly active biosurfactants with specific properties for specific applications are produced in large amounts. Therefore, the overexpression of genes involved in the biosynthesis of surfactants and emulsifiers and the control of these genes is an important goal to be achieved.
