DEGRADATION OF OLESTRA, A NON CALORIC FAT REPLACER, BY MICROORGANISMSISOLATED FROM ACTIVATED-SLUDGE AND OTHER ENVIRONMENTS

Olestra is a non-caloric fat substitute consisting of fatty acids este rified to sucrose. Previous work has shown that olestra is not metabol ized in the gut and is excreted unmodified in human feces. To better u nderstand the fate of olestra in engineered and natural environments, aerobic bacteria and fungi that degrade olestra were enriched from sew age sludges, soils and municipal solid waste compost not previously ex posed to olestra. Various mixed and pure cultures were obtained from t hese sources which were able to utilize olestra as a sole carbon and e nergy source. The fastest growing enrichment was obtained from activat ed sludge and later yielded an olestra-degrading pure culture of Pseud omonas aeruginosa. This mixed culture extensively degraded both C-14-f atty acid labeled olestra and C-14-sucrose labeled olestra during 8 da ys of incubation. Longer-term incubation with pure cultures of II aeru ginosa demonstrated that >98% of C-14-sucrose labeled olestra and >72% of C-14-fatty acid labeled olestra was mineralized to CO2 after 69 da ys. These results indicate that olestra degraders are present in envir onments not previously exposed to olestra and that olestra can serve a s a sole carbon and energy source. Furthermore, a common bacterial spe cies was isolated from activated sludge and shown to have the ability to degrade olestra.