Aspergillus kawachii produces inulinase activity in submerged cultures using semi-synthetic medium

ROJAS N.L.; CHESINI, M.; CONTRERAS ESQUIVEL, J.C; CAVALITTO, S

Boca del Río, Veracruz, México

Congreso; Fourth international Congress Food Science and Food Biotechnology in Developing Countries.; 2010

Sociedad Mexicana de Biotecnología y Bioingeniería

Inulin, a fructose polymer found as a reserve carbohydrate in the roots and tubers of plants such as Jerusalem artichoke, chicory and dahlia, represents a potential source of fructose and inulo-oligosaccharides that can be used as sweeteners and functional food additives. This fructan consists of a linear chain of fructose (b-2,1-link) with a terminal glucose unit. Inulin is depolymerized by two types of inulinase:exoinulinase (b-D-fructan fructohydrolase, EC 3.2.1.80) and endoinulinase (2,1-b-D-fructan fructanohydrolase,ECb-3.2.1.7). Inulinases are produced by many microorganisms, including bacteria, yeasts, and fungi. The gender Aspergillus has been reported as one of the most used for inulinases production. Particularly, the grass grade specie A. kawachii, a white fungus whom enzymes are involved in the degradation of the main components of agroindustrial residues such as starch, cellulose, hemicellulose and pectins has been reported to produce inulinases in solid state fermentation using pineapple pomace as carbon and energy source. In this study, the capability of A kawachii to produce inulinase in submerged semi synthetic medium using inuline as carbon source was studied. A. kawachii was cultured batchwise in Erlenmeyer flask using a mineral medium with inulin (10g/l) and triptein as carbon and nitrogen source respectively. Cultures were carried out in an orbital shaker, at 30 ºC and 200 RPM for 72 hours. Samples were taken every 12 hs and centrifuged to 10000 RPM for 10 min. Pellet was washed and used for dried weight determination. Supernatant was kept at -20 until remaining inulin and inulinase activity determination. The highest inulinase activity was 54 mU/ml from 2.2 g/l of biomass at 48 h fermentation which is higher that reported by others authors, which shows that A. kawachii is able to produce inulinase and it can be used as an alternative to inuline hidrolisis. Considering the purification, cloning and over expression of this protein, the production of this enzyme in a semi synthetic medium is a promisory strategy to achieve these objectives.