Colonization of Aspergillus japonicus on synthetic materials and application to the production of fructooligosaccharides

Abstract

The ability of Aspergillus japonicus ATCC 20236 to colonize different synthetic materials (polyurethane foam, stainless steel sponge, vegetal fiber, pumice stones, zeolites, and foam glass) and to produce fructooligosaccharides (FOS) from sucrose (165 g/L) is described. Cells were immobilized in situ by absorption, through direct contact with the carrier particles at the beginning of fermentation. Vegetal fiber was the best immobilization carrier as A. japonicus grew well on it (1.25 g/g carrier), producing 116.3g/L FOS (56.3g/L 1-kestose, 46.9 g/L 1-nystose, and 13.1g/L 1-beta-fructofuranosyl nystose) with 69% yield (78% based only in the consumed sucrose amount), giving also elevated activity of the beta-fructofuranosidase enzyme (42.9 U/mL). In addition, no loss of material integrity, over a 2 day-period, was found. The fungus also immobilized well on stainless steel sponge (1.13 g/g carrier), but in lesser extents on polyurethane foam, zeolites, and pumice stones (0.48, 0.19, and 0.13 g/g carrier, respectively), while on foam glass no cell adhesion was observed. When compared with the FOS and beta-fructofuranosidase production by free A. japonicus, the results achieved using cells immobilized on vegetal fiber were closely similar. It was thus concluded that A. japonicus immobilized on vegetal fiber is a potential alternative for high production of FOS at industrial scale.

Production of thermostable xylanase by thermophilic fungal strains isolated from maize silage

“…Los productos de PCR fueron visualizados en 1,5% (w/v) gel de agarosa teñido con bromuro de etidio. the species growth and development (Mussatto et al, 2009b). In the present study, the corn cobs sample presented WAI value of 2.55 g gel per g dry material, which is similar to that reported by other authors for this same substrate (Buenrostro-Figueroa et al, 2014;Mussatto et al, 2009a) as well as for other substrates already used in SSF processes, including cork oak (Mussatto et al, 2009a), wheat bran, and pecan nutshell (Orzua et al, 2009).…”

“…Therefore, materials with low CHP values are desired (Mussatto et al, 2009b;Robledo et al, 2008). The CHP value obtained for corn cobs in the present study was 32.6%.…”

“…Therefore, determining the WAI and CHP of the material that is desired for use as supportsubstrate is very important because these properties are directly related to the capacity of the material to absorb water and, as a consequence, to be invaded and colonized by the microorganisms. In brief, the WAI and CHP values allow estimating if the material presents characteristics suitable for use as support-substrate in SSF systems (Mussatto, Aguilar, Rodrigues, & Teixeira, 2009b;Mussatto et al, 2009a). WAI reflects the ability of the material to absorb water, and depends on the availability of hydrophilic groups to be bonded with water molecules as well as on the gel-forming capacity of the macromolecules (Mussatto et al, 2009a).…”

Typical Mexican Agroindustrial Residues as Supports for Solid-State Fermentation

“…WAI indicates the sample capacity to absorb water and depends on the availability of hydrophilic groups that bind water molecules and on the gel forming capacity of macromolecules (Mussatto et al, 2009a). In the present study, the highest WAI value was found in CH, which was four times higher than those obtained for CC and CS (Fig.…”

“…The materials were pre-treated by boiling during 10 min, washed three times with distilled water and subsequently dried at 60°C for 24-48 h (Mussatto et al, 2009a) All of them were milled until to obtain a particle size of 0.60 mm (Orzua et al, 2009). …”