Characterization of an extracellular β-d -fructofuranosidase produced by Aspergillus niveus during solid-state fermentation (SSF) of cassava husk

Abstract

Here, Aspergillus niveus produced an extracellular b-D-fructofuranosidase during SSF of cassava husk. This enzyme was purified 8.5-fold (recovery of 5.2%). A 37-kDa protein band was observed after 8% SDS-PAGE. Native molecular mass is 91.2 kDa. Optimal temperature and pH of activity were 558C and 4.5, respectively. The enzyme was stable at 508C for 1 hr, and 80% of its activity was retained after 1 hr at pH 8.0. The enzymatic activity was improved by Mn Practical applicationsb-D-Fructofuranosidase is an enzyme that can be applied to different industrial sectors, especially food and beverage industries. It is responsible for the hydrolysis of sucrose and yields an equimolar mixture of D-glucose and D-fructose, named as inverted sugar syrup, with broad applications in the confectionery industry. The Aspergillus niveus enzyme hydrolyzed only sucrose here and can be considered a true invertase, showing its potential for application to invert sugar production.Besides, the use of cassava husk for enzyme production means an interesting utilization route of this agroindustrial residue. Thus, characterization of this enzyme is an important step for identification of its potential for practical applications. Cassava (Manihot esculenta Crantz) is an important source of food in different tropical countries such as those located in Asia, Africa, and Latin America (Lateef & Ojo, 2016;Zhang et al., 2016). The main part of this plant is the root, which has 62% moisture content, 1.3% of fiber, 1.1% of liquid waste, and 34% of carbohydrates (Prado, Martins, Alcalde, Zeoula, & Marques, 2000). As for its carbohydrate composition, cassava root contains up to 90% starch in terms of dry weight (Zhang et al., 2016). The residues generated from the cassava processing can be classified into four groups: peels from initial processing, fibrous byproducts, starch residues, and wastewater effluents; the solid residues from cassava and flour processing are termed bagasse (Ubalua, 2007;Zhang et al., 2016) | M AT ER I AL S A N D M E TH ODS | The microorganism and culture conditionsThe filamentous fungus A. niveus, stored in the culture collection of the Laboratory of Microbiology of Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, University of São Paulo, was maintained in PDA (potato-dextrose-agar) slants at 48C until use. New cultures were started by scraping 30-day-old cultures, and the spores were inoculated into PDA slants preautoclaved for 15 min at 1208C and 1.5 atm.SSF was conducted using different agroindustrial residues or products (sugar cane bagasse, corncob, cassava husk, oatmeal, rye flour, wheat bran, or barley bagasse) as a substrate humidified with tap water (1:1 wt/vol), and preautoclaved at 1208C and 1.5 atm for 15 min. Sugar cane bagasse, cassava husk, and barley bagasse were dried before hand at 608C for 48 hr. After that, 10 g of a solid substrate was inoculated with 1 mL of a spore suspension (10 5 spores/mL) to obtain the concentration of 10 4 spores/g of substrate, and the mixture was incubated at 308C for...

Purification and biochemical characterization of β-d-fructofuranosidase fromBacillussubtilisLYN12

“…These results were in accordance with Yamamoto et al (). The inability to hydrolyse inulin, maltose and lactose indicates that the enzyme is a true β‐ d ‐fructofuranosidase (Fernandes et al, ). True invertases are required for the production of invert sugar syrups, alcoholic beverages, sucrose fermentation and hydrolysis of sugarcane molasses (Kulshrestha et al, ; Nadeem et al, ).…”

“…The inhibition by the ions Cu 2+ and Hg 2+ also caused reduction in enzyme activity in B. cereus TA‐11 (Yoon et al, ), B. infantis ATCC 15697 (Warchol et al, ), Lb. reuteri CRL 1100 (De Gines et al, ) and A. niveus (Fernandes et al, ). However, an elevation in enzymic activity was observed in the presence Mg 2+ and Fe 2+ which was similarly reported in B. infantis ATCC 15697 (Warchol et al, ).…”

“…These results were in accordance to B. cereus TA‐11 (Yoon et al, ), Lb. reuteri CRL 1100 (De Gines et al, ), T. neapolitana DSM 4359 (Dipasquale et al, ) and A. niveus (Fernandes et al, ). This feature indicates that the enzyme does not depend on metal ions and is capable of independent function.…”

“…The inhibition by the ions Cu 2+ and Hg 2+ also caused reduction in enzyme activity in B. cereus TA-11 (Yoon et al, 2007), B. infantis ATCC 15697 (Warchol et al, 2002), Lb. reuteri CRL 1100 (De Gines et al, 2000) and A. niveus (Fernandes et al, 2017).…”

Production of short‐chain fructooligosaccharides (scFOS) using extracellular β‐D‐fructofuranosidase produced byAspergillus thermomutatus

“…For example, the production of β‐D‐fructofuranosidase by Aspergillus caespitosus using wheat bran was 32‐fold higher than that obtained with sucrose as additional carbon source (Alegre et al, ). Wheat bran was also used for the enzyme production by Fusarium graminearum (Gonçalves et al, ), while cassava husk was used for β‐D‐fructofuranosidase production by Aspergillus niveus (Fernandes, Jorge, & Guimarães, ). High intracellular titers of β‐fructofuranosidase were also obtained from the yeast Aureobasidium sp.…”