Some chemical and physical properties of extracellular polysaccharides produced by Butyrivibrio fibrisolvens strains

Abstract

Most strains of Butyrivibriofibrisolvens 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 <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 H1Ob) 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-. 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-, more viscous. EPs from strains CF3 and HlOb 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 HlOb 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.

Structural and Rheological Properties of Exopolysaccharides Produced by Some Lactic Acid Bacterial Strains Isolated from Palm Wine

“…) position of IR spectra of EPS of bacteria indicated polysaccharide [38,40,41]. The range of values for the region where the intense broad stretching peak occurred in this study was within the range reported by Wang et al [36] that the IR spectra of Lactobacillus plantarum KF5 EPS showed the presence of -OH group at around 3307 cm -1…”

“…On the contrary, Pawar et al [49] reported a peak at 1038.92 cm -1 of EPS obtained from saline soil bacterium which corresponds to stretching of C-O, alcohol, ether and phenol groups. [40]. "Also, the carboxyl and hydroxyl groups in spectra are preferred groups for flocculation processes similar to polyelectrolyte characteristics [36,57].…”

Anaerobic Production of Extracellular Polysaccharide by Butyrivibrio fibrisolvens nyx

“…For example, the highest yield of EP by strain nyx occurred with 30 to 40 g of glucose per liter; similar levels of optimal carbohydrates benefited EP production by Xanthomonas campestris, with the highest yields of xanthan gum at glucose or sucrose levels of 30 to 50 g/liter (39). The highest yield of purified EP from glucose (20.1%) by strain nyx was higher than that reported for crude EP preparations from other Butyrivibrio strains (up to 16.3% yield) with 1% glucose (18).…”

Comparative assessment of exopolymer production and chemical characteristics of two environmental biofilm isolates of Pseudomonas aeruginosa

“…According to Simon et al [2] EPS gel is not a passive matrix but exhibits physical, chemical, and electrical responses to surrounding environment [3] . Although EPS are important for the attachment of cells on natural and engineered surfaces, the physiological control systems responsible for modulating polymer formation are not well understood [4] . Some studies [5] have examined the composition of bacterial EPS and reported the presence of mono-polysaccharides, glycol-proteins and glucoseamines as moieties [6] .…”

“…Some studies [5] have examined the composition of bacterial EPS and reported the presence of mono-polysaccharides, glycol-proteins and glucoseamines as moieties [6] . In laboratory cultures it is seen that EPS production is not initiated until the late log phase [4] . EPS also provides protection to the microorganisms from biocidal action and predation.…”