Aspergillus welwitschiae inulinase enzyme cocktails obtained on agro-material inducers for the purpose of fructooligosaccharides production

Abstract

Production of fructooligosaccharides (FOS) is a trending topic due to their prebiotic effect becoming increasingly important for the modern human diet. The most suitable process for FOS production is the one using fungal inulinases. Introduction of new fungal inulinase producers and their implementation in production of inulinase enzymes is therefore gaining interest. This study provides a new approach to FOS synthesis by fungal enzyme complex without prior separation of any specific enzyme. Inulinase enzyme complexes could be used for the synthesis of FOS in two possible ways - hydrolysis of inulin (FOS_h) and transfructosylation process of sucrose (FOS_s), as demonstrated here. Depending on the fungal growth inducing substrate, a variety of inulinase enzyme complexes was obtained - one of which was most successful in production of FOS_h and another one of FOS_s. Substrates derived from crops: triticale, wheat bran, Jerusalem artichoke and Aspergillus welwitschiae isolate, previously proven as safe for use in food, were utilized for production of inulinase enzyme cocktails. The highest FOS_s production was obtained by enzyme complex rich in β-fructofuranosidase, while the highest FOS_h production was obtained by enzyme complex rich in endoinulinase. Both FOS_h and FOS_s showed antioxidant potential according to ABTS and ORAC, which classifies them as a suitable additive in functional food. Simultaneous zymographic detection of inulinase enzymes, which could contribute to expansion of the knowledge on fungal enzymes, was developed and applied here. It demonstrated the presence of different inulinase isoforms depending on fungal growth substrate. These findings, which rely on the innate ability of fungi to co-produce all inulinases from a cocktail, could be useful as a new, easy approach to FOS production by fungal enzymes without their separation and purification, contributing to cheaper and faster production processes.

Keywords: Aspergillus; Endoinulinase; Exoinulinase; Glucosyl hydrolase; Jerusalem artichoke; Prebiotics; Triticale; β-fructofuranosidase.