Utilization of cassava wastes in the production of fructosyltransferase by Rhizopus stolonifer LAU 07

Abstract

A newly isolated strain of Rhizopus stolonifer LAU 07 was evaluated for the production of fructosyltransferase (FTase), the enzyme responsible for the conversion of sucrose to fructooligosaccharide (FOS), a heathful food ingredient using locally available cassava wastes in both solid state (SSF, cassava peel) and submerged fermentations (SmF, cassava steep liquor). High titers of enzyme of more than 20 U/g were obtained when 5-15 % inoculum sizes were used with minimal supplementation of cassava peels with yeast extract. Maximum FTase yield of 32.87 U/ml was obtained after 96 h of fermentation in cassava steep liquor, that was not supplemented with any nutrient. The systems are advantageous and economical for the production of FOS, in that the complex substrates do not require extensive supplementation to produce the enzyme with acceptable titer. The FTase yielded 34 % of FOS (1-kestose, GF2; nystose, GF3) using 60 % (w/v) sucrose as the substrate. As far as we know, this is the first contribution towards the production of FTase and FOS by a species of Rhizopus using low-cost complex media obtained from cassava peel and cassava steep liquor. The large-scale availability of these materials can make the process industrially relevant especially in Nigeria, where these agricultural wastes/residues are generated in abundance.