Streptococcus agalactiae (group B Streptococcus, GBS) is a gram-positive bacterium that is an asymptomatic colonizer commonly found in the gastrointestinal and genitourinary tract of healthy adults. GBS is also the most common cause of life-threatening bacterial infections in newborns and is emerging as a pathogen in immunocompromised and diabetic adults. The GBS cell wall and covalently linked capsular polysaccharides (CPS) are vital to the protection of the bacterial cell and act as virulence factors. GBS-CPS have been successfully used to produce conjugate vaccines for all currently identified GBS serotypes. However, the mechanisms of biosynthesis and assembly of CPS and the other cell wall components remain poorly defined due to their complex surface structures. In this biosynthetic study of the GBS cell wall-CPS complex, glycolipids with varying lengths of glycosyl-chains were discovered. Among those, one of the smallest glycolipids (named GBS Lipid-α) was structurally characterized. Lipid-α is involved in GBS saccharide metabolism and presumably acts as a glycosyl acceptor to elongate the glycosyl chain. GBS Lipid-α was determined to be a 3-monosaccharide 1,2 acyl glycerol with a molecular mass in the range of m/z = 724-808. GBS Lipid-α is highly heterogenic with various acyl groups and glycosyl moieties. This knowledge will pave the way for future studies to elucidate the entire metabolic pathway and genes involved. The Lipid-α pathway may also exist in other bacterial species and has the potential to be a biomarker for future drug development.

lipid A, group B Streptococcus, Streptococcus agalactiae, capsular polysaccharides (CPS)

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

[*]O[C@@H]1[C@@H](CO)O[C@@H](OC[C@H]2O[C@@H](O[C@@H]3[C@@H](O)[C@H]([*])O[C@H](CO)[C@@H]3O)[C@H](NC(C)=O)[C@@H](O)[C@@H]2O[C@@H]2O[C@H](CO)[C@H](O)[C@H](O[C@]3(C(=O)O)C[C@H](O)[C@@H](NC(C)=O)[C@H]([C@H](O)[C@H](O)CO)O3)[C@H]2O)[C@H](O)[C@H]1O

980.873 g/mol (C₃₇H₆₀R₂N₂O₂₈, R = next and previous repeats, not counted in mol weight)

Streptococcus agalactiae (group B Streptococcus, GBS) is a gram-positive bacterium that is an asymptomatic colonizer commonly found in the gastrointestinal and genitourinary tract of healthy adults. GBS is also the most common cause of life-threatening bacterial infections in newborns and is emerging as a pathogen in immunocompromised and diabetic adults. The GBS cell wall and covalently linked capsular polysaccharides (CPS) are vital to the protection of the bacterial cell and act as virulence factors. GBS-CPS have been successfully used to produce conjugate vaccines for all currently identified GBS serotypes. However, the mechanisms of biosynthesis and assembly of CPS and the other cell wall components remain poorly defined due to their complex surface structures. In this biosynthetic study of the GBS cell wall-CPS complex, glycolipids with varying lengths of glycosyl-chains were discovered. Among those, one of the smallest glycolipids (named GBS Lipid-α) was structurally characterized. Lipid-α is involved in GBS saccharide metabolism and presumably acts as a glycosyl acceptor to elongate the glycosyl chain. GBS Lipid-α was determined to be a 3-monosaccharide 1,2 acyl glycerol with a molecular mass in the range of m/z = 724-808. GBS Lipid-α is highly heterogenic with various acyl groups and glycosyl moieties. This knowledge will pave the way for future studies to elucidate the entire metabolic pathway and genes involved. The Lipid-α pathway may also exist in other bacterial species and has the potential to be a biomarker for future drug development.

lipid A, group B Streptococcus, Streptococcus agalactiae, capsular polysaccharides (CPS)

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

CCCCCCCC/C=C\CCCCCCCC(=O)OC(COC(=O)CCCCCCCCCCCCCCC)CO[C@H]1O[C@H](CO)[C@@H](O)[C@H](O)[C@H]1O

757.103 g/mol (C₄₃H₈₀O₁₀)

Exopolysaccharides (EPSs) produced by lactic acid bacteria possess various bioactivities and potential attractions for scientific exploration and commercial development. An EPS-producing bacterial strain, RSG7, was previously isolated from the pepino and identified as Leuconostoc mesenteroides. Based on the analyses of high-performance size exclusion chromatography, high-performance ion chromatography, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and methylation, the RSG7 EPS was identified as a dextran with a molecular weight of 5.47 × 106 Da and consisted of α-(1→6) glycosidic linkages as backbone and α-(1→2), α-(1→3), α-(1→4), and α-(1→6) glycosidic linkages as side chains. Scanning electron microscopy observed a honeycomb-like porous structure of RSG7 dextran, and this dextran formed aggregations with irregular hill-shaped lumps according to atomic force microscopy analysis. Physical-chemical investigations suggested that RSG7 dextran possessed excellent viscosity at high concentration, low temperature, and high pH; showed a superior emulsifying capacity of tested vegetable oils than that of hydrocarbons; and owned the maximal flocculating activity (10.74 ± 0.23) and flocculating rate (93.46 ± 0.07%) in the suspended solid of activated carbon. In addition, the dextran could coagulate sucrose-supplemented milk and implied potential probiotics in vitro. Together, these results collectively describe a valuable dextran with unique characteristics for exploitation in food applications

Dextran, Structural characterization, Leuconostoc mesenteroides RSG7, pepino, physical-chemical properties

SMILES errors: -6)?DGlcp(1-6)/?DGlcp(1-6)?DGlcp(1-6)?DGlcp(1-6)[?DGlcp(1-3)]?DGlcp(1-6)/n=18/[?DGlcp(1-2)[?DGlcp(1-4)?DGlcp(1-3)?DGlcp(1-3)?DGlcp(1-3)?DGlcp(1-6)]?DGlcp(1-3)]?DGlcp(1-6)?DGlcp(1-:
SMILES error: could not calculate brutto descriptors of a molecule from SMILES [*]OC[C@H]1OC(OC[C@H]2OC(OC[C@H]3OC(OC[C@H]4OC(OC[C@H]5OC(OC[C@H]6OC(OC[C@H]7OC(OC[C@H]8OC(OC[C@H]9OC(OC[C@H]%10OC(OC[C@H]%11OC(OC[C@H]%12OC(OC[C@H]%13OC(OC[C@H]%14OC(OC[C@H]%15OC(OC[C@H]%16OC(OC[C@H]%17OC(OC[C@H]%18OC(OC[C@H]%19OC(OC[C@H]%20OC(OC[C@H]%21OC(OC[C@H]%22OC(OC[C@H]%23OC([*])[C@H](O)[C@@H](O)[C@@H]%23O)[C@H](O)[C@@H](OC%23O[C@H](COC%24O[C@H](CO)[C@@H](O)[C@H](OC%25O[C@H](CO)[C@@H](O)[C@H](OC%26O[C@H](CO)[C@@H](O)[C@H](OC%27O[C@H](CO)[C@@H](OC%28O[C@H](CO)[C@@H](O)[C@H](O)[C@H]%28O)[C@H](O)[C@H]%27O)[C@H]%26O)[C@H]%25O)[C@H]%24O)[C@@H](O)[C@H](O)[C@H]%23OC%23O[C@H](CO)[C@@H](O)[C@H](O)[C@H]%23O)[C@@H]%22O)[C@H](O)[C@@H](OC%22O[C@H](CO)[C@@H](O)[C@H](O)[C@H]%22O)[C@@H]%21O)[C@H](O)[C@@H](O)[C@@H]%20O)[C@H](O)[C@@H](O)[C@@H]%19O)[C@H](O)[C@@H](O)[C@@H]%18O)[C@H](O)[C@@H](OC%18O[C@H](CO)[C@@H](O)[C@H](O)[C@H]%18O)[C@@H]%17O)[C@H](O)[C@@H](O)[C@@H]%16O)[C@H](O)[C@@H](O)[C@@H]%15O)[C@H](O)[C@@H](O)[C@@H]%14O)[C@H](O)[C@@H](OC%14O[C@H](CO)[C@@H](O)[C@H](O)[C@H]%14O)[C@@H]%13O)[C@H](O)[C@@H](O)[C@@H]%12O)[C@H](O)[C@@H](O)[C@@H]%11O)[C@H](O)[C@@H](O)[C@@H]%10O)[C@H](O)[C@@H](OC%10O[C@H](CO)[C@@H](O)[C@H](O)[C@H]%10O)[C@@H]9O)[C@H](O)[C@@H](O)[C@@H]8O)[C@H](O)[C@@H](O)[C@@H]7O)[C@H](O)[C@@H](O)[C@@H]6O)[C@H](O)[C@@H](OC6O[C@H](CO)[C@@H](O)[C@H](O)[C@H]6O)[C@@H]5O)[C@H](O)[C@@H](O)[C@@H]4O)[C@H](O)[C@@H](O)[C@@H]3O)[C@H](O)[C@@H](O)[C@@H]2O)[C@H](O)[C@@H](O)[C@@H]1O
Invalid SMILES [*]OC[C@H]1OC(OC[C@H]2OC(OC[C@H]3OC(OC[C@H]4OC(OC[C@H]5OC(OC[C@H]6OC(OC[C@H]7OC(OC[C@H]8OC(OC[C@H]9OC(OC[C@H]%10OC(OC[C@H]%11OC(OC[C@H]%12OC(OC[C@H]%13OC(OC[C@H]%14OC(OC[C@H]%15OC(OC[C@H]%16OC(OC[C@H]%17OC(OC[C@H]%18OC(OC[C@H]%19OC(OC[C@H] OC(OC[C@H]%21OC(OC[C@H]"OC(OC[C@H]%23OC([*])[C@H](O)[C@@H](O)[C@@H]%23O)[C@H](O)[C@@H](OC%23O[C@H](COC%24O[C@H](CO)[C@@H](O)[C@H](OC%25O[C@H](CO)[C@@H](O)[C@H](OC%26O[C@H](CO)[C@@H](O)[C@H](OC%27O[C@H](CO)[C@@H](OC%28O[C@H](CO)[C@@H](O)[C@H](O)[C@H]%28O)[C@H](O)[C@H]%27O)[C@H]%26O)[C@H]%25O)[C@H]%24O)[C@@H](O)[C@H](O)[C@H]%23OC%23O[C@H](CO)[C@@H](O)[C@H](O)[C@H]%23O)[C@@H]"O)[C@H](O)[C@@H](OC"O[C@H](CO)[C@@H](O)[C@H](O)[C@H]"O)[C@@H]%21O)[C@H](O)[C@@H](O)[C@@H] O)[C@H](O)[C@@H](O)[C@@H]%19O)[C@H](O)[C@@H](O)[C@@H]%18O)[C@H](O)[C@@H](OC%18O[C@H](CO)[C@@H](O)[C@H](O)[C@H]%18O)[C@@H]%17O)[C@H](O)[C@@H](O)[C@@H]%16O)[C@H](O)[C@@H](O)[C@@H]%15O)[C@H](O)[C@@H](O)[C@@H]%14O)[C@H](O)[C@@H](OC%14O[C@H](CO)[C@@H](O)[C@H](O)[C@H]%14O)[C@@H]%13O)[C@H](O)[C@@H](O)[C@@H]%12O)[C@H](O)[C@@H](O)[C@@H]%11O)[C@H](O)[C@@H](O)[C@@H]%10O)[C@H](O)[C@@H](OC%10O[C@H](CO)[C@@H](O)[C@H](O)[C@H]%10O)[C@@H]9O)[C@H](O)[C@@H](O)[C@@H]8O)[C@H](O)[C@@H](O)[C@@H]7O)[C@H](O)[C@@H](O)[C@@H]6O)[C@H](O)[C@@H](OC6O[C@H](CO)[C@@H](O)[C@H](O)[C@H]6O)[C@@H]5O)[C@H](O)[C@@H](O)[C@@H]4O)[C@H](O)[C@@H](O)[C@@H]3O)[C@H](O)[C@@H](O)[C@@H]2O)[C@H](O)[C@@H](O)[C@@H]1O

The present study aims to analyze the structural characterization and antioxidant activity of a novel exopolysaccharide from Rhizopus nigricans (EPS2-1). For this purpose, EPS2-1 was purified through DEAE-52, Sephadex G-100, and Sephadex G-75 chromatography. The structural characterization of EPS2-1 was analyzed using high-performance gel permeation chromatography (HPGPC), Fourier transform infrared spectroscopy (FT-IR), methylation analysis, nuclear magnetic resonance (NMR) spectra, transmission electron microscope (TEM), and atomic force microscope (AFM). The results revealed that EPS2-1 is composed of mannose (Man), galactose (Gal), glucose (Glc), arabinose (Ara), and Fucose (Fuc), and possesses a molecular weight of 32.803 kDa. The backbone of EPS2-1 comprised →2)-α-D-Manp-(1→ and →3)-β-D-Galp-(1→, linked with the O-6 position of (→2,6)-α-D-Manp-(1→) of the main chain is branch α-D-Manp-(1→6)-α-D-Manp-(1→, linked with the O-6 positions of (→3)-β-D-Galp-(1→) of the main chain are branches →4)-β-D-Glcp-(1→ and →3)-β-D-Galp-(1→, respectively. Finally, we demonstrated that EPS2-1 also shows free radical scavenging activity and iron ion reducing ability. At the same time, EPS2-1 could inhibit the proliferation of MFC cells and increase the cell viability of RAW264.7 cells. Our results suggested that EPS2-1 is a novel polysaccharide, and EPS2-1 has antioxidant activity. In addition, EPS2-1 may possess potential immunomodulatory and antitumor activities. This study promoted the application of EPS2-1 as the functional ingredients in the pharmaceutical and food industries.

exopolysaccharide, Structural characterization, Antioxidant activity, Rhizopus nigricans

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
3,3,2,2	aDManp	101.95	80.21	71.32	68.19	74.5	62.30
3,3,6,6	aDManp	100.83	71.42	71.95	68.03	74.53	67.20
3,3,2	aDManp
3,3,6,6,6	aDManp	103.60	71.44	71.95	68.66	74.67	62.40
3,3,6	aDManp
3,3	aDManp	99.62	80.12	71.58	68.06	74.52	67.20
3,6,4	SUG
3,6	bDGlcp	103.84	74.17	71.58	80.16	76.69	61.67
3	bDGalp	104.49	71.31	81.5	69.82	74.81	70.76
6,3	SUG
6	bDGalp	104.48	71.97	81.58	70.25	76.40	62.26
	bDGalp	104.49	71.31	81.5	69.82	74.81	70.76


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
3,3,2,2	aDManp	5.23	4.01	3.88	3.60	3.70	3.69-3.81
3,3,6,6	aDManp	4.85	3.94	3.80	3.65	3.78	3.71-3.78
3,3,2	aDManp
3,3,6,6,6	aDManp	4.99	4.01	3.78	3.58	3.71	3.68-3.82
3,3,6	aDManp
3,3	aDManp	5.05	3.98	3.86	3.60	3.70	3.72-3.77
3,6,4	SUG
3,6	bDGlcp	4.46	3.30	3.63	3.64	3.47	3.79-3.95
3	bDGalp	4.47	3.57	3.68	4.05	3.87	3.86-3.96
6,3	SUG
6	bDGalp	4.37	3.47	3.60	3.97	3.64	3.69
	bDGalp	4.47	3.57	3.68	4.05	3.87	3.86-3.96


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
3,3,2,2	aDManp	101.95/5.23	80.21/4.01	71.32/3.88	68.19/3.60	74.5/3.70	62.30/3.69-3.81
3,3,6,6	aDManp	100.83/4.85	71.42/3.94	71.95/3.80	68.03/3.65	74.53/3.78	67.20/3.71-3.78
3,3,2	aDManp
3,3,6,6,6	aDManp	103.60/4.99	71.44/4.01	71.95/3.78	68.66/3.58	74.67/3.71	62.40/3.68-3.82
3,3,6	aDManp
3,3	aDManp	99.62/5.05	80.12/3.98	71.58/3.86	68.06/3.60	74.52/3.70	67.20/3.72-3.77
3,6,4	SUG
3,6	bDGlcp	103.84/4.46	74.17/3.30	71.58/3.63	80.16/3.64	76.69/3.47	61.67/3.79-3.95
3	bDGalp	104.49/4.47	71.31/3.57	81.5/3.68	69.82/4.05	74.81/3.87	70.76/3.86-3.96
6,3	SUG
6	bDGalp	104.48/4.37	71.97/3.47	81.58/3.60	70.25/3.97	76.40/3.64	62.26/3.69
	bDGalp	104.49/4.47	71.31/3.57	81.5/3.68	69.82/4.05	74.81/3.87	70.76/3.86-3.96

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

R1 = SUG
Warning = sub-repeat ending at aDManp: large unit count (14) was reduced to 5
[*]O[C@H]1[C@@H](O)[C@H](O)[C@@H](CO)O[C@@H]1O[C@H]1[C@@H](O)[C@H](O)[C@@H](CO)O[C@@H]1O[C@H]1[C@@H](O)[C@H](O)[C@@H](CO)O[C@@H]1O[C@H]1[C@@H](O)[C@H](O)[C@@H](CO)O[C@@H]1O[C@H]1[C@@H](O)[C@H](O)[C@@H](CO)O[C@@H]1O[C@H]1[C@@H](O)[C@H](O)[C@@H](CO)O[C@@H]1O[C@H]1[C@@H](O)[C@H](O)[C@@H](CO[C@H]2O[C@H](CO[C@H]3O[C@H](CO[C@H]4O[C@H](CO[C@H]5O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]5O)[C@@H](O)[C@H](O)[C@@H]4O)[C@@H](O)[C@H](O)[C@@H]3O)[C@@H](O)[C@H](O)[C@@H]2O)O[C@@H]1O[C@H]1[C@@H](O)[C@@H](CO[C@@H]2O[C@H](CO)[C@@H](O[1*])[C@H](O)[C@H]2O)O[C@@H](O[C@@H]2[C@@H](O)[C@H]([*])O[C@H](CO[C@@H]3O[C@H](CO)[C@H](O)[C@H](O[1*])[C@H]3O)[C@@H]2O)[C@@H]1O

2430.099 g/mol (C₉₀H₁₄₈R₄O₇₅, R = next and previous repeats / residue superclass(es), not counted in mol weight)