scholarly journals Inhibitory Effect of Depolymerized Sulfated Galactans from Marine Red Algae on the Growth and Adhesion of Diarrheagenic Escherichia coli

Marine Drugs ◽  
2019 ◽  
Vol 17 (12) ◽  
pp. 694 ◽  
Author(s):  
Yixiang Liu ◽  
Wenqiang Liu ◽  
Yanbo Wang ◽  
Yu Ma ◽  
Ling Huang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Monosaccharide Composition ◽  
Inhibitory Effect ◽  
Enterotoxigenic Escherichia Coli ◽  
Sulfated Polysaccharides ◽  
Natural Polymers ◽  
Sulfated Galactans

Active polysaccharides as safe and natural polymers against bacterial diarrhea have been reconsidered as an alternative to antibiotics. This work investigated the inhibiting effect of depolymerized sulfated galactans from Eucheuma serra and Gracilaria verrucosa on the growth and adhesion of diarrheagenic enterotoxigenic Escherichia coli (ETEC) K88. Results showed that the sulfated polysaccharides with molecular weight distribution ≤20.0 kDa exhibited antibacterial activity against ETEC K88. A structure–activity study revealed that the anti-ETEC K88 activity of sulfated polysaccharides is strictly determined by their molecular weight distribution, sulfate group content, and monosaccharide composition. In addition, the promoted nucleic acid release and the fluorescence quenching of membrane proteins were observed after the treatment with selected polysaccharides. Scanning electron microscopy further confirmed that the depolymerized sulfated galactans can effectively inhibit ETEC K88 adhesion. In conclusion, depolymerized sulfated galactans exhibited an inhibitory effect on the growth and adhesion of ETEC K88.

scholarly journals Antibacterial Activity of Sulfated Galactans from Eucheuma serra and Gracilari verrucosa against Diarrheagenic Escherichia coli via the Disruption of the Cell Membrane Structure

Marine Drugs ◽  
2020 ◽  
Vol 18 (8) ◽  
pp. 397 ◽  
Author(s):  
Yixiang Liu ◽  
Yu Ma ◽  
Zhaohua Chen ◽  
Donghui Li ◽  
Wenqiang Liu ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antibacterial Activity ◽  
Cell Membrane ◽  
Enterotoxigenic Escherichia Coli ◽  
Fluorescence Labeling ◽  
Sulfated Polysaccharides ◽  
Wall Structure ◽  
Gram Positive Bacteria ◽  
Sulfated Galactans ◽  
Significant Attention

Seaweed sulfated polysaccharides have attracted significant attention due to their antibacterial activity. This work investigated the antibacterial activity and mechanism of depolymerized sulfated galactans from Eucheuma serra (E. serra) and Gracilaria verrucosa (G. verrucosa) against enterotoxigenic Escherichia coli (ETEC) K88. The results show that removing the metal ions improves the anti-ETEC K88 activity of the galactans. The fluorescence labeling study confirmed that the sulfated galactans penetrated the cell walls and eventually reached the interior of the ETEC K88. Nucleic acid staining and intracellular protein leakage were also observed, indicating the destruction of permeability and integrity of the cell membrane. Interestingly, the two polysaccharides exhibited no effect on the proliferation of the selected Gram-positive bacteria and yeast. This indicates that the cell wall structure of the microorganisms could influence the bacteriostatic activity of the sulfated polysaccharides, as well. These results suggest that the sulfated seaweed polysaccharides might have potential application value in antibacterial diarrhea.

Effect of Molecular-Weight Distribution on Physical Properties of Natural and Synthetic Polymers

1948 ◽  
Vol 21 (3) ◽  
pp. 654-666 ◽  
Author(s):  
B. L. Johnson
Keyword(s):  
Molecular Weight ◽  
Physical Properties ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Synthetic Polymers ◽  
Natural Polymers ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Styrene Copolymers ◽  
Weight Distributions

Abstract The molecular weights of rubberlike polymers are average values for mixtures of macromolecules which differ greatly in size. The heterogeneity of natural rubber was recognized as early as 1929 by Whitby. The fact that solutions of higher quality crude rubbers are more viscous than lower quality rubbers was observed by Axelrod in 1905. Other workers have separated rubber solutions into fractions of differing molecular weight and have studied the properties of the fractions. In the case of synthetic polymers, these heterogeneous mixtures of molecules have been characterized by fractional precipitation and construction of molecular-weight distribution curves. The particular type of distribution determined in this investigation is that obtained from weight average properties based on viscosity measurements of fractions of the polymers. Application of these methods to the characterization of natural polymers confirmed observations that a variety of molecular-weight distributions existed in the case of the natural polymers. The physical properties of the natural polymers having these diverse molecular-weight distributions were well known. Therefore a correlation of their physical properties and weight distributions seemed pertinent to an evaluation of the fractionation technique. Such a correlation had not been possible on early butadiene-styrene copolymers because of the similarity of the distributions then obtained, even under different polymerization conditions.

Extraction and Partial Purification of Protease from Bilimbi (Averrhoa bilimbi L.)

2013 ◽  
Vol 10 (2) ◽  
pp. 29
Author(s):  
Normah Ismail ◽  
Nur' Ain Mohamad Kharoe
Keyword(s):  
Molecular Weight ◽  
Protein Content ◽  
Ammonium Sulfate ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Protease Activity ◽  
Protein Concentration ◽  
Temperature Stability ◽  
Partial Purification ◽  
Ammonium Sulfate Precipitation

Unripe and ripe bilimbi (Averrhoa bilimbi L.) were ground and the extracted juices were partially purified by ammonium sulfate precipitation at the concentrations of 40 and 60% (w/v). The collected proteases were analysed for pH, temperature stability, storage stability, molecular weight distribution, protein concentration and protein content. Protein content of bilimbi fruit was 0.89 g. Protease activity of both the unripe and ripe fruit were optimum at pH 4 and 40°C when the juice were purified at 40 and 60% ammonium sulfate precipitation. A decreased in protease activity was observed during the seven days of storage at 4°C. Molecular weight distribution indicated that the proteases protein bands fall between IO to 220 kDa. Protein bands were observed at 25, 50 and 160 kDa in both the unripe and ripe bilimbi proteases purified with 40% ammonium sulfate, however, the bands were more intense in those from unripe bilimbi. No protein bands were seen in proteases purified with 60% ammonium sulfate. Protein concentration was higher for proteases extracted with 40% ammonium sulfate at both ripening stages. Thus, purification using 40% ammonium sulfate precipitation could be a successful method to partially purify proteases from bilimbi especially from the unripe stage. 

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