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HYDROLYSIS OF TOPINAMBUR (JERUSALEM-ARTICHOKE) FRUCTANS BY EXTRACELLULAR INULINASE OF KLUYVEROMYCES-MARXIANUS VAR BULGARICUS
No full textExtracellular inulinase from Kluyveromyces marxianus var. bulgaricus catalysed the hydrolysis of pure inulin and the extracts of fresh and dried topinambur (Jerusalem artichoke). At an enzyme concentration of 10 IU g-1 of substrate the three substrates were hydrolysed respectively to 65.3, 77.3 and 83.9%. The relationship between the extent of hydrolysis, reaction time and enzyme concentration was studied and a kinetic model of hydrolysis was derived
EXTRACELLULAR INULINASE FROM 4 YEASTS
No full textFour strains of yeasts, Candida kefyr, Candida pseudotropicalis var. lactosa, Kluyveromyces cicerisporus and Kluyveromyces fragilis, were studied for the production of inulinase. High enzyme activity (22.4-32.0 U/mL; 9.7-16.0 U/mg protein) was detected in the culture supernatant when the yeasts were grown in a medium containing aqueous extract of fresh Jerusalem artichoke (topinambur) tubers as carbon source. Maximum inulinase activity was obtained at 28 °C for C. kefyr and C. pseudotropicalis, and 32 °C for K. cicerisporus and K. fragilis, in 6-day-old cultures. The inulinase activity for all four strains exhibited a pH optimum of 4.7, a temperature optimum of 60 °C; the activation energy ranged from 3.2 to 4.8 Kcal/mole, and the half-life at 45 °C from 25 to 40 h. Ultrafiltration and following dialysis of the supernatants gave a degree of purification of the crude enzyme varying from 5.9 to 12.0. In preliminary experiments with topinambur extract, 89 and 92% of saccharification of 5% fructan expressed as total carbohydrate to fructose at 6 h was obtained with C. pseudotropicalis and K. cicerisporus extracellular enzyme (1 U/mL), respectively
PURIFICATION AND CHARACTERIZATION OF THE EXTRACELLULAR INULINASE FROM KLUYVEROMYCES-CICERISPORUS
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EXTRACELLULAR CELLULOLYTIC COMPLEX FROM MORCHELLA-CONICA - PRODUCTION AND PURIFICATION
No full textA cellulolytic complex was obtained from the ascomycetes Morchella conica grown on a mineral medium with a cellulose powder as the substrate. Maximum yield of the activities tested (carboxymethylcellulase, avicelase, filter paper, cotton activity, cotton degrading activity and β-glucosidase) was reached at 8 d of fermentation. Optimum activity conditions were found at pH 5 and 60°C for CMCase; 4.5 and 40°C for AVase. Half-life at 45 and 50°C was longer than 96 h for both CMCase and AVase. The crude enzyme, after ultrafiltration and dialysis, was purified by DEAE-Sepharose CL 6B ion-exchange chromatography. The 'cellulase' was separated into four fractions which were characterized with both polyacrylamide-gel- and SDS- electrophoresis. Three different endoglucanases (Endo I, Endo II and Endo III and three different cellobiohydrolases (Exo I, Exo II and Exo III) were assessed, the Exo I was present in the form of three isoenzymes
Production of K5 polysaccharides of different molecular weight by Escherichia coli
No full textAn investigation was made of the molecular weight of the Escherichia coil antigenic K5 polysaccharide. Two components with molecular weights of 16,000 and 1,500 were observed. The ratio of these two components depended on a lyase produced by the same E. coli. This lyase acts by a beta-elimination mechanism to depolymerize the K5. At the end of the fermentation the thermally treated (to inactivate the lyase) and untreated twenty-four-hour-old cultures each contained two K5 components of different M(w), in different ratios. The two components were monitored over a fermentation time-course. C-13-NMR spectrometry was employed to verify the lyase mechanism of action
EXTRACELLULAR K5 POLYSACCHARIDE OF ESCHERICHIA-COLI - PRODUCTION AND CHARACTERIZATION
No full textThe extracellular form of the K5 polysaccharide was produced, purified and characterized from a strain of Escherichia coli, the maximum fermentation yield (320 mg/L) was obtained after 15 h. The polysaccharide, recovered by precipitation with cold ethanol (80%), was purified through a process employing an enzymic deproteination step using fungal protease. Characterization by TLC and GC chromatography revealed that the K5 was mainly composed of glucuronic acid and N-acetyl-glucosamine. The C-13-NMR spectrum showed the product's structure to be the same as that of the K5 capsular polysaccharide described in the literature
Investigation of a capsular polysaccharidic component of Escherichia coli
No full textI polisaccaridi capsulari di molti batteri gram negativi possono presentare attivita' antigene. L'antigene K5 di alcuni ceppi di Escherichia coli, infettanti le vie urinarie nell'uomo, mostra raramente attivita' immunogenica; cio' e' presumibilmente attribuibile alla sua struttura analoga alla desulfoeparina. Detto polisaccaride e' stato ottenuto e descritto in letteratura nella forma capsulare. Con questo lavoro si e' inteso produrre il componente polisaccaridico K5 nella forma extracellulare, impiegando quattro diversi terreni colturali. Vengono riportate le rese di fermentazione e l'analisi della frazione degli zuccheri neutri dei polisaccaridi extracellulari ottenuti per precipitazione con etanolo. I grezzi polisaccaridici sono stati inoltre caratterizzati mediante metodiche colorimetriche, cromatografia su strato sottile e gascromatografia, nonche' comparati tramite spettro NMR 13C, identificando la componente polisaccaridica del K5 prevalentemente in uno dei prodottiThe capsular polysaccharidic component of many gram negative bacteria may have antigenic properties. The K5 antigen of some Escherichia coli strains infecting the human urinary tract has rare immunogenic activity, presumably because of its structure similar to desulfoheparin. Such a polysaccharide has already been obtained from cells and is described in the literature. The present work had the aim of producing the K5 polysaccharidic component extracellularly, employing four different cultural media. The fermentation yield and the analysis of the neutral sugar fraction of the extracellular polysaccharides obtained by precipitation with ethanol, are reported. The crude polysaccharides were then characterized by colorimetric methods, TLC chromatography and gas-chromatography and were compared by 13C NMR spectra, identifying the K5 polysaccharidic component especially in one produc
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