Influence of some sugars on xylanase production by Aspergillus awamori in solid state fermentation

Abstract

Aspergillus awamori showed high extracellular endoxylanase (100 U/ml) and beta-xylosidase activities (3.5 U/ml) when grown on milled sugar cane bagasse as the principal carbon source without treatment. Partial characterization of xylanases showed that the apparent values of Km were 3.12 &plusmn; 0.05 mg/ml for endoxylanase (in birchwood xylan) and 0.45 &plusmn; 0.05 mM for beta-xylosidase (in p -nitrophenyl beta-D-xylanopiranoside). Corresponding values of Vmax were 6.63 &plusmn; 0.02 and 0.078 &plusmn; 0.02 mumol/min. Gradual repression of endoxylanase activity was observed when increasing concentrations of glucose and xylose (1, 2, 4, 6 and 8 g of carbohydrate / 4 g of sugar cane bagasse) were added to production media. In contrast, beta-xylosidase activity was stimulated using low levels of carbohydrates (1 g xylose or glucose/ 4 g of sugar cane bagasse).<br>O cultivo de Aspergillus awamori em bagaço de cana, finamente dividido e sem tratamento prévio, favoreceu a produção de níveis elevados de endo-xilanase (100 U/ml) e beta-xilosidase (3.5 U/ml) extracelulares. A caracterização parcial das enzimas xilanolíticas permitiu estabelecer os parâmetros cinéticos aparentes, sendo Km igual a 3.12 ( 0.05 mg/ml para endox-xilanase (xilana birchwood) e 0.45 ( 0.05 mM para beta-xylosidase (p-nitrofenil beta-D-xilanopiranosideo). Os correspondentes valores de Vm foram 6.63 ( 0.02 e 0.078 ( 0.02 mimol/min. Observou-se uma repressão gradual da atividade endo-xilanásica quando concentrações crescentes de glicose e xilose (1, 2, 4, 6 e 8 g de carboidrato / 4 g de bagaço de cana) foram adicionadas aos meios de produção. Contrariamente, a atividade beta-xilosidásica foi estimulada quando níveis baixos de açúcares simples foram utilizados (1 g de xilose ou glicose/ 4 g de bagaço de cana)

Xylanase production by a thermo-tolerant Bacillus species under solid-state and submerged fermentation

“…Catabolite repression by xylose in the course of xylan (from corn cob) degradation could also be distinct possibility. Catabolite repression by xylose has been established by various reports (Archana and Satnarayanan, 1997;Lemos and Junior, 2002). Corn cob itself has much higher contents of xylose and xylan compared to wheat bran.…”

“…If xylan degradation took place more significantly, then catabolite repression by xylose was also a probability. Repression of xylanase by more than 1% xylose has been observed in a strain of A. awamori under SSF (Lemos and Junior, 2002). It was suggested that xylose had two possible effects.…”

Optimization of Xylanase Production byThermomyces lanuginosusin Solid State Fermentation

“…Prior to optimization and for the purpose of an initial determination of xylanase activity, 10 g of sterilized wheat bran in 250-ml Erlenmeyer flasks was inoculated with 8 ml of liquid seed culture, diluted 1:4 with sterile water. Flasks, prepared in triplicate, were then fermented for 4 d at 40 C at 80% relative humidity (RH) in a humidity chamber (Sheldon Manufacturing, Cornelius, OR).…”

“…8) Depending on its botanical origin, xylan can possess a number of sidelinked groups, comprised of acetyl, arabinofuranosyl, and glucuronosyl residues. 9) Thermophilic Thermomyces lanuginosus has demonstrated growth on a variety of carbon sources, with an optimum growth temperature of [40][41][42][43][44][45][46][47][48][49][50] C, [10][11][12] and is particularly noted for its inability to produce cellulase. 13) Compared to those from mesophilic sources, enzymes from thermophiles tend to be more thermostable, a characteristic believed to be achieved through minor alterations in protein structure.…”

Hydrolysis of galacto-oligosaccharides in soy molasses by α -galactosidases and invertase from Aspergillus terreus

“…α-Galactosidase has been purified from several microbial sources including Aspergillus ficcum (Zapater et al, 1990), Trichoderma reesei (Zeilinger et al, 1993) and A. oryzae (Prasshanth and Mulimani, 2005), with multiple forms of α-galctosidase being reported (Luonteri et al, 1998;Manzanares et al, 1998;Ademark et al, 2001), Although, α-galactosidases are the main enzymes required for GO hydrolysis, and invertases can also be important to increase the hydrolysis yield, since GO are substrates for both the enzymes. The Aspergillus genus has been characterized as a good producer of several hydrolytic enzymes (de Rezende and Felix 1999;Noronha et al, 2002;Lemos et al, 2002;Souza-Mota et al, 2005). A. terreus, when grown on wheat straw, secreted multiple forms of α-galactosidase.…”