SURFACE-ACTIVE PROPERTIES OF THE CULTURE FILTRATES OF A MICROCOCCUS SPECIES GROWN ON N-ALKANES AND SUGARS

The surface active properties of the culture filtrates (from shake fla sk fermentation for 140 h at 37 +/- 1 degrees C) of a species of Micro coccus are described in terms of surface tension, emulsification and f oamability using carbon sources, such as n-dodecane, n-tetradecane, n- hexadecane and n-octadecane as the different n-alkanes, adn sucrose, f ructose, glucose and mannose as the different sugars. The surface tens ion for the culture filtrate was lowest with dodecane (45.2 mN m(-1)) followed by tetradecane (49.1 mN m(-1)), hexadecane (50.8 mN m(-1)) an d octadecane (58.3 mN m(-1)) among the n-alkanes; for the sugars, sucr ose had the lowest value (51.4 mN m(-1)) followed by fructose (52.8 mN m(-1)), mannose (57.3 mN m(-1)) and glucose (57.5 mN m(-1)). All the n-alkane systems showed 70-80% emulsification of a test mixture compos ed of equal volumes of kerosene and the respective culture filtrate. B ut only 84 and 50% of the formed emulsions with tetradecane and dodeca ne, respectively, remained stable during 48 h of ageing. Although the culture filtrate of fructose showed the highest initial emulsification of 62% among the sugars, almost no decay of the formed emulsion (41%) was observed with that of sucrose. Foamability noted with a single no zzle spurger was appreciable with the sucrose and fructose systems, bu t negligible with the n-alkane systems. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.