Materials 21

The wood rotting basidiomycete S. commune ATCC 38548 is employed to produce the extracellular polysaccharide called Schizophyllan. The fungus is grown on agar slants (7 mL of melted agar in a 20-mL glass tube sealed with a cotton plug) supplemented with 39 g L potato dextrose agar and 5 g L yeast extract (both Difco, Detroit, MI). The slants are inoculated with a piece of agar (cut with a small knife) and incubated for 1 wk at room temperature with subsequent storing of the covered slants at 4...

Notes

The purification of the solvents acetonitrile and methanol is a very important factor which affects the yield of B-cellobiosyl fluoride. Freshly distilled solvents are recommended. 2. The cellulase powder should be stored at low temperature and with prevention of water ingress. This minimized clumping and, hence, inaccuracies when weighing out small amounts of the catalyst. It also lowers the risk of enzyme deactivation caused by hydrolytic or microbial effects. Efforts should be made to...

Analysis of Phenolics

Add 10 nmol of a suitable phenolic acid to the sample 0.4 mL as an internal standard. Cinnamic acid 1 mL of a 10 nmol mL stock solution in water is recommended since this phenolic is well separated from the common cell wall phenolics under the HPLC conditions described here. 2. Add 100 L of glacial acetic acid to the sample and vortex mix. The pH of the solution should be about 3.0 and should be tested with pH paper. The low pH ensures that phenolics are in the acid form and will be...

Principle of the Method

A combined sequential use of glycosidase together with glycosyltransferase, including a cofactor regeneration, transforms complicated multistep reactions into a one-pot reaction 5 ,thus avoiding laborious purifications of the intermediates. This reduces considerably the costs of the procedure, using a cheaper glycosidase, and a cheap substrate as well. Reversed hydrolysis of the disaccharide intermediate is blocked by its further glycosyltransferase-mediated sialylation, thus forming an...

Schizophyllan Structure

Schizophyllan Structure

The filamentous growing fungus Schizophyllum commune ATCC 38548 1 secretes a neutral homoglucan trivial name Schizophyllan that consists of a backbone chain of 1,3-P-d-glucopyranose units linked with single 1,6-bonded P-d-glucopyranoses at about every third glucose molecule in the basic chain Fig. 1 . The molecular weight varies between 6 and 12106 g mol 2 . Schizophyllan dissolves in water as a triple helix with protruding pendant P-1,6-linked d-glucose units originating from the outside of...

Allomorph Characterization by FTIR and FTRaman Spectroscopy

Cellulose Spektrum

The FTIR spectrum for the synthetic cellulose, for the region 4000-2200 cm-1 is given in Fig. 4 and for the region 2000-650 cm-1 in Fig. 5. In each case the precise frequency of absorption is also given for each detected peak. The corresponding Raman spectrum for this material is given in Fig. 6 again with the precise Raman shift frequencies given at the top of the spectrum. These spectra are compared with those obtained for pulp and Viscose in Fig. 7 FTIR spectra and Fig. 8 FT-Raman spectra...

Mannuronan Synthesis

Alginate Pseudomonas

The enzymatic interconversions of the various hexoses found in polysaccharides and glycoproteins normally take place either on the unsubstituted sugars, their phosphate esters, or at the sugar nucleotide levels. In a few cases, however, epimerization reactions take place after the polysaccharides are formed. This type of postpolymerization epimerization is a feature of several uronic-acid containing polysaccharides found both in eukaryotes and in bacteria. These reactions are exemplified by C-5...

Introduction

Enzymatic Polymerization Glucose

Cellulose, a homopolysaccharide whose glucose units are connected through 13 1 -4 glycosidic linkages, has been of great interest in many scientific and application fields as polymeric drugs and new biomaterials 1 . So far, highly pure samples of cellulose and its derivatives have been produced for functional macromolecules, specimen for basic crystallographical research, enzyme substrates, and so on starting from various kinds of naturally occurring celluloses. The elongation of cellulose...

Downstream Production Of Xanthan

Xanthan Gum Production From Xanthomonas

Manufacture of high-molecular-weight compounds with thickener properties has been traditionally related to plants, seeds, and seaweeds. These compounds have been named gums. The rheological properties of their solutions show important alterations depending on uncontrolled variables such as weather, and their manual-collection labor cost can often influence their market price. Production of molecules with thickener properties from microorganisms was an important advance. This production is made...

Spectrophotometric Method

Dnsa Method For Sugar Estimation

The only satisfactory spectrophotometric method available for alginate measurement was originally developed by Kennedy and Bradshaw 14 to assay alginate from brown seaweeds and, subsequently, modified to measure bacterial alginates 3,15 . The following procedure, adapted from Brivonese and Sutherland 3 , is used 1. Add 1 cm3 of 0.3 PHMBH CL- in 1 sodium acetate to 0.5 cm3 of culture supernatant eventually diluted to obtain a final alginate concentration less than 3 g.dm-3 into 1.5-cm3 Eppendorf...

Analytical Methods

Diagram Xanthan Production

To check the state of the fermentation, some analytical techniques must be used. The main components to be analyzed are biomass, xanthan, carbon source sucrose , and nitrogen source ammonium concentrations. Dissolved oxygen is also a very important component to consider, but it is usually monitored on line by means of an electrode. Biomass concentration is obtained by means of the measurement of the optical density at 540 nm of the diluted broth. Biomass concentration can be determined...

Cannon-fenske Viscometer Tube

Cannon Fenske Viscometer Tubes

Alginates are a group of polysaccharides occurring as structural components or as capsular materials in the cell wall of the brown seaweeds or soil bacteria, respectively 1 . About 30,000 metric tons of sodium alginates per year are currently used in the food, pharmaceutical, textile and paper industries as thickening, stabilising and jellifying agents 2 . Since only a few of the many species of brown algae are suitable and are limited in abundance and location for commercial alginate...

Xanthan Production

Xanthan Biosynthesis

The production stage can be divided into three steps fermentor sterilization and preparation, inoculation, and fermentation itself. Fermentor Sterilization and Preparation 1. The concentrated medium without carbon source is sterilized in the vessel and the concentrated solution of the carbon source sucrose is sterilized separately and afterwards introduced into the 2. The pH electrode must be calibrated before fermentor sterilization. 3. All the exits, inputs and electrodes of the fermentor...