SYNTHESIS OF FRUCTOOLIGOSACCHARIDES USING EXTRACELLULAR ENZYMES FROMRHODOTORULASP

Abstract

ABSTRACT Considering the great biodiversity of the still unexploited Brazilian environment, efforts were made to select microorganisms capable of producing fructooligosaccharide (FOS). Amongst 495 interesting isolated yeast strains, one in particular, identified as a Rhodotorula red yeast strain isolated from flowers from the Brazilian tropical biomass, was able to produce an effective thermostable extracellular enzyme, with both sucrose hydrolytic and transfructosylating activities. The best operational conditions for this enzyme were determined to be in a pH range from 3.8 to 4.3 and at temperatures of around 65C. Under these conditions, the transfructosylating activity reached its maximum, being more than 10 times higher than the hydrolytic activity. The synthesis of fructooligosaccharides from sucrose resulted in total conversion of the substrate into FOS (48%), glucose (31.3%) and fructose (20.7%). In addition, it was shown that the synthesized FOS had a prebiotic effect, promoting the growth of probiotic bacteria. PRACTICAL APPLICATIONS The search for new enzymes for oligosaccharide production, using either microbial screening or molecular engineering, became necessary as a result of the increasing number of applications of these carbohydrates in the cosmetic, agrochemical, pharmaceutical and food industries. In this work, the Rhodotorula sp. isolated from Brazilian biomes was shown to be capable of producing an extracellular fructosyltransferase enzyme with good prospects for further studies aiming an industrial application, because it can convert sucrose into fructooligosaccharide (FOS), giving high yields (50%). It is worthwhile to emphasize the high optimum temperature and low pH value of the enzyme operation, which make it possible to work in a nonsterile environment for FOS production. It is also remarkable the ability of this yeast type (Rhodotorula), of growing on diverse alternative media and agricultural by-products (molasses, corn steel liquor, grape must, whey ultrafiltrate).