Some chemical and physical properties of extracellular polysaccharides produced by Butyrivibrio fibrisolvens strains
Autor: | R B Hespell, S H Gordon, Y W Ha, R J Stack, Rodney J. Bothast |
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Rok vydání: | 1991 |
Předmět: |
Spectrophotometry
Infrared Bacteroidaceae Sodium chemistry.chemical_element Polysaccharide Applied Microbiology and Biotechnology Viscosity Species Specificity Butyrivibrio medicine Food science chemistry.chemical_classification Minerals Ecology biology Chemistry Polysaccharides Bacterial Apparent viscosity biology.organism_classification Shear rate Solutions Glucose Biochemistry Xanthan gum Food Science Biotechnology Butyrivibrio fibrisolvens medicine.drug Research Article |
Zdroj: | Applied and environmental microbiology. 57(7) |
ISSN: | 0099-2240 |
Popis: | Most strains of Butyrivibrio fibrisolvens are known to produce extracellular polysaccharides (EPs). However, the rheological and functional properties of these EPs have not been determined. Initially, 26 strains of Butyrivibrio were screened for EP yield and apparent viscosities of cell-free supernatants. Yields ranged from less than 1.0 to 16.3 mg per 100 mg of glucose added to the culture. Viscosities ranged from 0.71 to 5.44 mPa.s. Five strains (CF2d, CF3, CF3a, CE51, and H10b) were chosen for further screening. The apparent viscosity of the EP from each of these strains decreased by only 50 to 60% when the shear rate was increased from 20 to 1,000 s-1. Strain CE51 produced the EP having the highest solution viscosity. A detailed comparison of shear dependency of the EP from strain CF3 with xanthan gum showed that this EP was less shear sensitive than xanthan gum and, at a shear rate of 1,000 s-1, more viscous. EPs from strains CF3 and H10b were soluble over a wide range of pH (1 to 13) in 80% (vol/vol) ethanol-water or in 1% (wt/vol) salt solutions. The pH of 1% EP solutions was between 4.5 and 5.5. Addition of acid increased solution viscosities, whereas addition of base decreased viscosity. EPs from strains CF3, CE51, and H10b displayed qualitatively similar infrared spectra. Calcium and sodium were the most abundant minerals in the three EPs. The amounts of magnesium, calcium, and iron varied considerably among the EPs, but the potassium contents remained relatively constant. |
Databáze: | OpenAIRE |
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