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PubMedDate not supplied

[The selection and properties of Penicillium verruculosum mutants with enhanced production of cellulases and xylanases].

The paper describes three Penicillium verruculosum 28K mutants with about threefold enhanced production of five industrially important carbohydrases. The two-stage fermentation process that we developed provided a further two- to threefold increase in the production of carbohydrases. Physiological and biochemical studies showed that the synthesis of all five carbohydrases is inducible. Carboxymethylcellulase, xylanase, and beta-glucanase are synthesized under a common regulatory control, as is evident from the concurrent increase in the synthesis of these enzymes in the presence of microcrystalline cellulose. The synthesis of avicelase and beta-glucosidase is evidently induced by other cellulose- and hemicellulose-containing compounds present in the fermentation medium and, hence, is regulated independently of the three aforementioned enzymes.

Cellulase↗
PubMedDate not supplied

[New cellulases efficiently hydrolyzing lignocellulose pulp].

Commercial and pilot enzyme preparations from fungi of the genera Penicillium and Trichoderma have been compared with regard to their action on conifer wood pretreated with acidified aqueous ethanol (organosolve). In most experiments, enzymes from the genus Penicillium allowed higher yields of reducing sugars and glucose than those from Trichoderma. High beta-glucosidase activity is essential for deep pulp hydrolysis.

Cellulases↗
PubMed1990

[Cloning and expression of Clostridium thermocellum F7 cellulase genes in Escherichia coli and Bacillus subtilis cells].

The Clostridium thermocellum total DNA Sau 3A fragments' library was constructed on the basis of shuttle vector pMK4 for the Escherichia coli - Bacillus subtilis. 14 clones with endoglucanase activity and one with beta-glucosidase activity were selected in E. coli cells. Recombinant plasmids pCE were characterized by structural instability of various degree in B. subtilis cells. The results of the physical mapping, analysis of gene products in E. coli mini-cells as well as the DNA-DNA blot hybridization have led to conclusion on cloning of 7 individual genes for endoglucanases. Up to 3 polypeptides of various molecular weight corresponding to the products of cel gene were revealed in E. coli mini-cells containing the recombinant plasmids. The hybridization analysis demonstrated considerable homology of the majority of cel genes.

Bacillus subtilis↗
PubMed1989

The effect of Trichoderma viride C-1 UV mutagenization on cellulases activity.

Trichoderma viride C-1 strain was irradiated with UV until the survival level of 0.03% was obtained. Sixteen mutants were isolated on the basis of the visible clearance zone around the colonies on the media with cellulose and glycerol. Then they were cultivated on a rotary shaker in the liquid Saunders medium supplemented with microcrystalline cellulose and comminuted sugar beet pulp. Exo-1,4-beta-glucanase, endo-1,4-beta-glucanase and beta-glucosidase were assayed in the supernatants of postcultural liquids at different time intervals of culture. The same mutants were characterized by higher biosynthesis level of exoglucanase (1.2-5.0 times) endoglucanase (1.2-2.5 times) and beta-glucosidase (1.5-1.7 times) when compared with the wild type strain.

Cellulase↗
PubMed1989

Novel O-linked carbohydrate chains in the cellulase complex (cellulosome) of Clostridium thermocellum. 3-O-Methyl-N-acetylglucosamine as a constituent of a glycoprotein.

Alkaline borohydride treatment of the cellulosome of Clostridium thermocellum yielded two major oligosaccharide-alditols, namely D-Galp-beta(1----4)-D-GalOH and (formula; see text) The compounds, isolated via gel permeation chromatography and high performance liquid chromatography, were analyzed by monosaccharide analysis, methylation analysis, gas-liquid chromatography/mass spectrometry, fast atom bombardment/mass spectrometry, and one- and two-dimensional 500-MHz (COSY, HOHAHA, ROESY) 1H NMR spectroscopy. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis combined with blotting technology indicated that the tetrasaccharide is mainly associated with one of the cellulosome subunits.

Acetylglucosamine↗
PubMed1988

Precise excision of the cellulose binding domains from two Cellulomonas fimi cellulases by a homologous protease and the effect on catalysis.

An endo-beta-1,4-glucanase (CenA) and an exo-beta-1,4-glucanase (Cex) were prepared from Escherichia coli expressing recombinant DNA of the cellulolytic bacterium Cellulomonas fimi. Purification was facilitated by the high affinities of these enzymes for cellulose. An extracellular C. fimi protease cleaved both enzymes in vivo in a highly specific manner. The affinity of the parent enzyme for cellulose was contained independently in an amino-terminal fragment (p20) of CenA and a carboxyl-terminal fragment (p8) of Cex. These fragments contained homologous amino acid sequences which were proposed to comprise cellulose binding domains. Corresponding fragments, p30 from CenA and p35 from Cex, which were unable to bind to cellulose, contained catalytic domains. In both enzymes, the two functional domains were joined by a hinge region consisting solely of prolyl and threonyl residues. The binding domain was excised from CenA by proteolytic cleavage immediately adjacent to the carboxyl terminus of this hinge. Cex was cleaved at an exactly analogous site. p30 and p35 retained several of the catalytic functions of their parent enzymes. However, p30 was less active than intact CenA against microcrystalline cellulose implying a critical role for the binding domain of CenA in the hydrolysis of crystalline substrate.

Actinomycetales↗
PubMed1986

Factors limiting the efficiency of cellulase enzymes.

The major reasons behind the low efficiency of enzymatic hydrolysis of cellulose are reviewed. The problem is a result of the heterogeneous nature of the hydrolysis reaction which involves a multicomponent soluble catalyst, an insoluble substrate and products which are both.

Bacteria↗
PubMed1988

[Induction of cellulases and xylanases in Aureobasidium pullulans].

The specificity or induction of wood-degrading enzymes using series of mono, di or polysaccharides as carbon source for the yeasts Geotrichum candidum and Trychosporon penicillatum and the yeast-like organism Aureobadidium pullulans were studied. The strain A. pullulans was the only one that when xylan or "steam exploded wood" were used as carbon source all the enzymes tested were found. This strain was unable to grow on carboxymethyl or Avicel cellulose. D-xylose was the nutritional inducer of beta-xylosidase and beta-xylanase but D-glucuronic acid induced CMCase activity and beta-glucosidase was produced with every carbon source. The 1,4 beta-xylobiose was not an inducer of beta-xylanase but with the structural 1,2-beta- and 1,3-beta-xylobiose isomers high levels of this enzyme were obtained.

Carbon↗