Fungus Penicillium Canescens Research Articles

Xylanase Production by Penicillium canescens on Soya Oil Cake in Solid-State Fermentation

There is an increasing interest for the organic residues from various sectors of agriculture and industries over the past few decades. Their application in the field of fermentation technology has resulted in the production of bulk chemicals and value-added products such as amino acid, enzymes, mushroom, organic acids, single-cell protein, biologically active secondary metabolites, etc. (Ramachandran et al., Bioresource Technology 98:2000-2009, 2007). In this work, the production of extracellular xylanase by the fungus Penicillium canescens was investigated in solid-state fermentation using five agro-industrial substrates (soya oil cake, soya meal, wheat bran, whole wheat bran, and pulp beet). The best substrate was the soya oil cake. In order to optimize the production, the most effective cultivation conditions were investigated in Erlenmeyer flasks and in plastic bags with 5 and 100 g of soya oil cake, respectively. The initial moisture content, initial pH, and temperature of the culture affected the xylanase synthesis. The optimal fermentation medium was composed by soya oil cake crushed to 5 mm supplemented with 3% and 4% (w/w) of casein peptone and Na(2)HPO(4) x 2H(2)O. After 7 days of incubation at 30 degrees C and under 80% of initial moisture, a xylanase production level of 18,895 +/- 778 U/g (Erlenmeyer flasks) and 9,300 +/- 589 U/g (plastic bags) was reached. The partially purified enzyme recovered by ammonium sulfate fractionation was completely stable at freezing and refrigeration temperatures up to 6 months and reasonably stable at room temperature for more than 3 months.

Isolation and characterization of extracellular α-galactosidases from Penicillium canescens

Two alpha-galactosidases were purified to homogeneity from the enzymatic complex of the mycelial fungus Penicillium canescens using chromatography on different sorbents. Substrate specificity, pH- and temperature optima of activity, stability under different pH and temperature conditions, and the influence of effectors on the catalytic properties of both enzymes were investigated. Genes aglA and aglC encoding alpha-galactosidases from P. canescens were isolated, and amino acid sequences of the proteins were predicted. In vitro feed testing (with soybean meal and soybean byproducts enriched with galactooligosaccharides as substrates) demonstrated that both alpha-galactosidases from P. canescens could be successfully used as feed additives. alpha-Galactosidase A belonging to the 27th glycosyl hydrolase family hydrolyzed galactopolysaccharides (galactomannans) and alpha-galactosidase C belonging to the 36th glycosyl hydrolase family hydrolyzed galactooligosaccharides (stachyose, raffinose, etc.) of soybean with good efficiency, thus improving the digestibility of fodder.

Isolation and characterization of extracellular pectin lyase from Penicillium canescens

Pectin lyase A (molecular weight 38 kD by SDS-PAGE, pI 6.7) was purified to homogeneity from culture broth of the mycelial fungus Penicillium canescens using chromatographic techniques. During genomic library screening, the gene encoding pectin lyase A from P. canescens (pelA) was isolated and sequenced, and the amino acid sequence was generated by applying the multiple alignment procedure (360 residues). A theoretical model for the three dimensional structure of the protein molecule was also proposed. Different properties of pectin lyase A were investigated: substrate specificity, pH- and temperature optimum of activity, stability under different pH and temperature conditions, and the effect of Ca2+ on enzyme activity. In the course of the laboratory trials, it was demonstrated that pectin lyase A from P. canescens could be successfully applied to production and clarification of juice.

Synthesis of xylanolytic enzymes and other carbohydrases by the fungus Penicillium canescens: Transformants with an altered copy number of the gene xlnR and an encoding transcriptional activator

A fragment of Penicillium canescens genomic DNA carrying the xlnR gene coding for a translational activator of xylanolytic genes was isolated. It was demonstrated that a loss of this function in genetically modified transformants resulted in a drastic decrease in the production of P. canescens major xylanases and had a negative effect on the syntheses of several other extracellular xylanases. An increase in the dose of the xlnR gene elevated the xylanolytic activity as well as the activities of a number of other auxiliary enzymes involved in xylan degradation. The activities of two P. canescens major secreted enzymes--beta-galactosidase and alpha-L-arabinofuranosidase-appeared weakly dependent on the translational activator xlnR.

Removal of Heavy Metal Ions Using the Fungus Penicillium Canescens

The potential use of the fungus Penicillium canescens for the removal of cadmium, lead, mercury and arsenic ions from aqueous solutions was evaluated in this study. Equilibrium biosorption of the heavy metal ions was attained in 4 h. The binding of heavy metal ions to P. canescens was clearly pH-dependent. Under acidic conditions, the heavy metal ion loading capacity increased with increasing pH, presumably as a result of heavy metal speciation and competition with hydrogen ions for the same binding sites. The adsorption of heavy metal ions attained a plateau value at ca. pH 5.0. The maximum adsorption capacities of the heavy metal ions studied onto the fungal biomass under non-competitive conditions were 26.4 mg/g for As(III), 54.8 mg/g for Hg(II), 102.7 mg/g for Cd(II) and 213.2 mg/g for Pb(II), respectively. The competitive adsorption capacities of the heavy metal ions were 2.0 mg/g for As(III), 5.8 mg/g for Hg(II), 11.7 mg/g for Cd(II) and 32.1 mg/g for Pb(II), respectively, at a 50-mg/l initial conce...

Mechanism of overproduction of secreted enzymes in the mycelial fungus Penicillium canescens

The fungus Penicillium canescens strain F178 (VKPM) and its niaD- mutant exhibited an increased capability of synthesizing extracellular enzymes beta-galactosidase (70-80 U/ml) and xylanase (100 U/ml). The synthesis was induced by arabinose and its catabolite, arabitol. A deficiency in arabitol dehydrogenase, leading to arabitol accumulation in the cell, was detected in the chain of reactions of arabinose catabolism. The increased synthesis of beta-galactosidase and xylanase in P. canescens is accounted for by (1) cellular accumulation of the inducer (arabitol) at low concentrations of arabinose in the medium and (2) prevalence of induction over repression.

Induction of the Synthesis of Endo-1,4-β-xylanase and β-Galactosidase in Original and Recombinant Strains of the Fungus Penicillium canescens

The induction of synthesis of the secreted enzymes endo-1,4-β-xylanase (EC 3.2.1.8) and β-galactosidase (EC 3.2.1.23) in original and recombinant Penicillium canescens strains has been studied. In all producer strains, the synthesis of these enzymes was induced by arabinose and its metabolite arabitol. The two enzymes differed in the concentration of arabinose required for induction: the synthesis of β-galactosidase was most pronounced at 1 mM, whereas maximum synthesis of endo-1,4-β-xylanase was observed at 5–10 mM. An increase in the number of endo-1,4-β-xylanase copies in the high-copy-number strain of the fungus suppressed the synthesis of β-galactosidase; the synthesis of endo-1,4-β-xylanase in the high-copy-number recombinant producing β-galactosidase was affected to a lesser extent. The amount of enzymes synthesized did not depend on the saccharide used as the sole source of carbon for growing the mycelium prior to its transfer to the inducer-containing medium.