The exopolysaccharide-producing fungus Penicillium purpurogenum JS03-21 from the acidic purple clay was screened to develop greater insights into microbial exopolysaccharide resources from extremophilic microorganisms. An exopolysaccharide JS1-1 was purified from the fermented broth of the aciduric fungus using a combination of ethanol precipitation, anion-exchange and size-exclusion chromatography. JS1-1 was found to be a neutral heteropolysaccharide composed of galactose, mannose and glucose in the ratio of 7.9:2.1:1.0, with a molecular weight of about 26 kDa. JS1-1 was subjected to a series of methylation and partial acid hydrolysis reactions, as well as being analyzed by one- and two-dimensional nuclear magnetic resonance, and the results of these analyses revealed JS1-1 to be a galactofuranose-rich polysaccharide. The main chain of JS1-1 contained two regions, including a galactose part composed of a repeating trisaccharide unit [i.e., →5)-β-D-Galf(1 → 5)-β-D-Galf(1 → 6)-β-D-Galf(1→], and a mannose section consisting of (1 → 6)-linked α-D-Manp residues. Two further segments [i.e., α-D-Glcp(1 → 2)-α-D-Galf (1 → and α-D-Galf(1 → 2)-α-D-Manp(1→] existed as branches that were linked to the O-2 atoms of the (1 → 6)-β-D-Galf and (1 → 6)-α-D-Manp regions of the main chain, respectively. The results of the current study demonstrate that JS1-1 is a unique polysaccharide that is rich in both α and β galactofuranose units and therefore different from most of the other known extracellular polysaccharides. The function of this polysaccharide is currently being researched in our laboratory.

NMR, extraction, heteropolysaccharide, Penicillium purpurogenum

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
6,5	bDGalf	109.3	82.5	77.4	82.5	76.6	63.4
6	bDGalf	109.3	82.5	77.4	82.5	76.6	63.4
2,2	aDGlcp	98.76	72.14	74.11	74.11	70.40	61.88
2	aDGalf	100.23	82.1	73.1	72.0	?	?
	bDGalf	106.92	88.39	76.38	83.21	72.11	70.29


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
6,5	bDGalf	5.08	4.18	4.12	4.17	3.88	3.71-3.84
6	bDGalf	5.08	4.18	4.12	4.17	3.88	3.71-3.84
2,2	aDGlcp	5.05	3.61	3.82	3.49	3.86	3.67-3.78
2	aDGalf	5.41	4.29	4.40	3.89	3.80	?
	bDGalf	5.37	4.30	4.28	4.12	3.78	3.67-3.83


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
6,5	bDGalf	109.3/5.08	82.5/4.18	77.4/4.12	82.5/4.17	76.6/3.88	63.4/3.71-3.84
6	bDGalf	109.3/5.08	82.5/4.18	77.4/4.12	82.5/4.17	76.6/3.88	63.4/3.71-3.84
2,2	aDGlcp	98.76/5.05	72.14/3.61	74.11/3.82	74.11/3.49	70.40/3.86	61.88/3.67-3.78
2	aDGalf	100.23/5.41	82.1/4.29	73.1/4.40	72.0/3.89	?/3.80	?/?
	bDGalf	106.92/5.37	88.39/4.30	76.38/4.28	83.21/4.12	72.11/3.78	70.29/3.67-3.83

The spectrum also has 2 signals at unknown positions (not plotted).

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

[*]O[C@H](CO)[C@@H]1O[C@@H](O[C@H](CO)[C@@H]2O[C@@H](OC[C@@H](O)[C@@H]3O[C@@H]([*])[C@H](O[C@H]4O[C@@H]([C@H](O)CO)[C@H](O)[C@H]4O[C@H]4O[C@H](CO)[C@@H](O)[C@H](O)[C@H]4O)[C@H]3O)[C@H](O)[C@H]2O)[C@H](O)[C@H]1O

810.705 g/mol (C₃₀H₅₀R₂O₂₅, R = next and previous repeats, not counted in mol weight)

The exopolysaccharide-producing fungus Penicillium purpurogenum JS03-21 from the acidic purple clay was screened to develop greater insights into microbial exopolysaccharide resources from extremophilic microorganisms. An exopolysaccharide JS1-1 was purified from the fermented broth of the aciduric fungus using a combination of ethanol precipitation, anion-exchange and size-exclusion chromatography. JS1-1 was found to be a neutral heteropolysaccharide composed of galactose, mannose and glucose in the ratio of 7.9:2.1:1.0, with a molecular weight of about 26 kDa. JS1-1 was subjected to a series of methylation and partial acid hydrolysis reactions, as well as being analyzed by one- and two-dimensional nuclear magnetic resonance, and the results of these analyses revealed JS1-1 to be a galactofuranose-rich polysaccharide. The main chain of JS1-1 contained two regions, including a galactose part composed of a repeating trisaccharide unit [i.e., →5)-β-D-Galf(1 → 5)-β-D-Galf(1 → 6)-β-D-Galf(1→], and a mannose section consisting of (1 → 6)-linked α-D-Manp residues. Two further segments [i.e., α-D-Glcp(1 → 2)-α-D-Galf (1 → and α-D-Galf(1 → 2)-α-D-Manp(1→] existed as branches that were linked to the O-2 atoms of the (1 → 6)-β-D-Galf and (1 → 6)-α-D-Manp regions of the main chain, respectively. The results of the current study demonstrate that JS1-1 is a unique polysaccharide that is rich in both α and β galactofuranose units and therefore different from most of the other known extracellular polysaccharides. The function of this polysaccharide is currently being researched in our laboratory.

NMR, extraction, heteropolysaccharide, Penicillium purpurogenum

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
2,2	aDGalf	104.2	78.21	74.4	82.3	?	?
2	aDManp	101.6	78.0	70.6	68.2	72.22	62.4
	aDManp	99.7	78.7	70.25	68.2	?	67.27


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
2,2	aDGalf	5.24	4.22	4.25	?	?	?
2	aDManp	5.26	4.12	4.03	3.70	3.86	3.77-3.93
	aDManp	5.20	4.22	3.99	3.70	3.83	3.71-3.79


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
2,2	aDGalf	104.2/5.24	78.21/4.22	74.4/4.25	82.3/?	?/?	?/?
2	aDManp	101.6/5.26	78.0/4.12	70.6/4.03	68.2/3.70	72.22/3.86	62.4/3.77-3.93
	aDManp	99.7/5.20	78.7/4.22	70.25/3.99	68.2/3.70	?/3.83	67.27/3.71-3.79

The spectrum also has 3 signals at unknown positions (not plotted).

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

[*]OC[C@H]1O[C@H]([*])[C@@H](O[C@H]2O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]2O[C@H]2O[C@@H]([C@H](O)CO)[C@H](O)[C@H]2O)[C@@H](O)[C@@H]1O

486.423 g/mol (C₁₈H₃₀R₂O₁₅, R = next and previous repeats, not counted in mol weight)