I. M. Gracheva

Immobilization of Champagne Yeasts by Inclusion into Cryogels of Polyvinyl Alcohol: Means of Preventing Cell Release from the Carrier Matrix

Wine champagnizing, a process involving the use of champagne yeasts immobilized by inclusion into cryogels of polyvinyl alcohol, has been studied. Treatment of yeast cells with the autoregulatory factor d1 was proposed as a means of preventing the cell release from the carrier matrix. Such a treatment inhibited growth and proliferation processes in yeast cells, without affecting the activity of fermentation; the resulting champagne had the same organoleptic and chemical characteristics as its counterparts obtained using conventional techniques.

Physiological and Biochemical Characteristics of Immobilized Champagne Yeasts and Their Participation in Champagnizing Processes: A Review

Methods for immobilizing champagne yeasts, physiological and biochemical characteristics of the immobilized cells, and problems of their utilization in the production of quality champagne wines are reviewed. Studies aimed at the development of efficient biocatalysts for champagnizing wines using bottle fermentation (methode champenoise) and tank processing (bulk, or Charmat process) based on the use of immobilized yeast cells are described. Data on the industrial use of such biocatalysts in countries manufacturing champagne wines are presented. Problems and prospects of further research in this field are discussed.

Preparation of High-Purity Cyclodextrin Glucanotransferase from Bacillussp. 1070

Two schedules have been developed for chromatographic purification of cyclodextrin glucanotransferase (CGTase) from a culture of Bacillussp. 1070. The purification on butyl-Toyopearl and on Cu(II)-iminodiacetic (IDA) agarose resulted in a 9.5-fold purification of the enzyme. The second schedule for purification (chromatography on butyl-Toyopearl and on DEAE-Sephacel) resulted in a 13.5-fold increase in the specific activity of CGTase. By electrophoresis under denaturing conditions, the enzyme purity was shown to be no less than 90%. According to preliminary data, CGTase consists of two isoenzymes with pI 5.1 and 5.3.

Purification and Characterization of endo-(1→4)-β-xylanase fromGeotrichum candidum 3C

A method of purification of endo-( 1 → 4)-β-xylanase (endoxylanase; EC 3.2.1.8) from the culture liquid ofGeotrichum candidum 3C, grown for three days, is described. The enzyme, purified 23-fold, had a specific activity of 32.6 U per mg protein (yield, 14.4%). Endoxylanase was shown to be homogeneous by SDS-PAGE (molecular weight, 60 to 67 kDa). With carboxymethyl xylan as the substrate, the optimum activity (determined viscosimetrically) was recorded at pH 4.0 (pI 3.4). The enzyme retained stability at pH 3.0-4.5 and 30–45°C for 1 h. With xylan from birch wood, the hydrolytic activity of the enzyme (ability to saccharify the substrate) was maximum at 50°C. In 72 h of exposure to 0.2 mg/ml endoxylanase, the extent of saccharification of xylans from birch wood, rye grain, and wheat straw amounted to 10,12, and 7.7%, respectively. At 0.4 mg/ml, the extent of saccharification of birch wood xylan was as high as 20%. In the case of birch wood xylan, the initial hydrolysis products were xylooligosaccharides with degrees of polymerization in excess of four; the end products were represented by xylobiose, xylotriose, xylose, and acid xylooligosaccharides.

Separation of Endo-1,4-β-xylanases from Geotrichum candidum3C with Various Abilities to Sorb on Insoluble Substrate

Culture liquid from Geotrichum candidum 3C was shown to contain three endoxylanase types: endoxylanase I that binds to cellulose, endoxylanase II that sorbs to insoluble xylan, and endoxylanase III that cannot sorb to insoluble substrate. The catalytic and substrate-binding domains of endoxylanase II were isolated.