PRODUCTION AND SECRETION OF THE POLYSACCHARIDE BIODISPERSAN OF ACINETOBACTER-CALCOACETICUS A2 IN PROTEIN SECRETION MUTANTS

Biodispersan is an extracellular anionic polysaccharide produced by Ac inetobacter calcoaceticus A2 that changes the surface properties of li mestone and acts both as a dispersant and as a grinding aid (E. Rosenb erg, C. Rubinovitz, A. Gottlieb, S. Rosenhak, and E. Z. Ron, Appl. En, iron. Microbiol. 54:317-322, 1988; E. Rosenberg, C. Rubinovitz, R Legm ann, and E. Z. Ron, Appl. Environ. Microbiol. 54:323-326, 1988; E. Ros enberg, Z. Schwartz, A Tenenbaum, C. Rubinovitz, R Legmann, and E. Z. Ron, J. Dispersion Sci. Technol. 10:241-250, 1989). Extracellular flui d also contains a high concentration of secreted proteins that create problems in the purification and application of biodispersan. In order to obtain preparations of biodispersan that contained smaller amounts of protein, we selected mutants of strain A2 that were defective in p rotein secretion. These mutants produced equal, or even higher, levels of total biodispersan compared with those of the parental strain. Mor eover, although there was a significant drop in the concentration of e xtracellular proteins in the medium, the secretion of biodispersan was unaffected. These results suggest that secretion mutants are potentia lly useful for the production of extracellular polysaccharides.