Recently, the production of exopolysaccharide from Pseudozyma sp. SY16, which is mannosylerythritol lipid-producing yeast, has been occasionally observed during industrial fermentations. Moreover, exopolysaccharides derived from microbes are in high demand for the production of biopolymers. Therefore, this study aimed to investigate the production and characteristics of the exopolysaccharide produced by this strain. In batch fermentations with this strain, the maximum production yield of exopolysaccharide (5.8 g/L) was obtained under olive oil supplementation as a carbon source with culture conditions of 30°C, pH 8.0, and 600 rpm. Through a series of liquid chromatography steps, the exopolysaccharide was successfully purified, and its emulsifying activity was demonstrated. In addition, two-dimensional nuclear magnetic resonance analysis revealed that the exopolysaccharide is a galactoglucomannan with a novel and unique structure, consisting of galactose, glucose, and mannose in the ratio of 1:5:3.

exopolysaccharide, fermentation, yeast, galactoglucomannan, Pseudozyma sp.

13C NMR data:
Linkage	Residue	C1	C2	C3	C4	C5	C6
2,4,4,2,4,4,2	aDGlcp	103.60-103.96	71.08-71.70	71.68-72.18	74.72-74.83	67.88-68.38	62.49-62.58
2,4,4,2,4,4	aDManp	99.68	80.22	?	?	?	?
2,4,4,2,4	aDGlcp	103.60-103.96	71.08-71.70	71.68-72.18	74.72-74.83	67.88-68.38	62.49-62.58
2,4,4,2	aDGlcp	103.60-103.96	71.08-71.70	71.68-72.18	74.72-74.83	67.88-68.38	62.49-62.58
2,4,4	aDManp	99.68	80.22	?	?	?	?
2,4	aDGlcp	103.60-103.96	71.08-71.70	71.68-72.18	74.72-74.83	67.88-68.38	62.49-62.58
2	aDGlcp	103.60-103.96	71.08-71.70	71.68-72.18	74.72-74.83	67.88-68.38	62.49-62.58
4	aDGalp
	aDManp	102.08	79.94	71.56	74.71	?	?


1H NMR data:
Linkage	Residue	H1	H2	H3	H4	H5	H6
2,4,4,2,4,4,2	aDGlcp	4.92-5.06	3.94-4.09	3.73-3.83	3.56-3.65	3.51-3.66	3.62-3.80
2,4,4,2,4,4	aDManp	4.97-4.99	3.90-3.92	4.02	?	?	?
2,4,4,2,4	aDGlcp	4.92-5.06	3.94-4.09	3.73-3.83	3.56-3.65	3.51-3.66	3.62-3.80
2,4,4,2	aDGlcp	4.92-5.06	3.94-4.09	3.73-3.83	3.56-3.65	3.51-3.66	3.62-3.80
2,4,4	aDManp	4.97-4.99	3.90-3.92	4.02	?	?	?
2,4	aDGlcp	4.92-5.06	3.94-4.09	3.73-3.83	3.56-3.65	3.51-3.66	3.62-3.80
2	aDGlcp	4.92-5.06	3.94-4.09	3.73-3.83	3.56-3.65	3.51-3.66	3.62-3.80
4	aDGalp	5.30-5.33	3.89-4.02	3.80-3.91	3.73-3.79	?	?
	aDManp	5.17	3.99	3.78	3.61	3.80	?


1H/13C HSQC data:
Linkage	Residue	C1/H1	C2/H2	C3/H3	C4/H4	C5/H5	C6/H6
2,4,4,2,4,4,2	aDGlcp	103.60-103.96/4.92-5.06	71.08-71.70/3.94-4.09	71.68-72.18/3.73-3.83	74.72-74.83/3.56-3.65	67.88-68.38/3.51-3.66	62.49-62.58/3.62-3.80
2,4,4,2,4,4	aDManp	99.68/4.97-4.99	80.22/3.90-3.92	?/4.02	?/?	?/?	?/?
2,4,4,2,4	aDGlcp	103.60-103.96/4.92-5.06	71.08-71.70/3.94-4.09	71.68-72.18/3.73-3.83	74.72-74.83/3.56-3.65	67.88-68.38/3.51-3.66	62.49-62.58/3.62-3.80
2,4,4,2	aDGlcp	103.60-103.96/4.92-5.06	71.08-71.70/3.94-4.09	71.68-72.18/3.73-3.83	74.72-74.83/3.56-3.65	67.88-68.38/3.51-3.66	62.49-62.58/3.62-3.80
2,4,4	aDManp	99.68/4.97-4.99	80.22/3.90-3.92	?/4.02	?/?	?/?	?/?
2,4	aDGlcp	103.60-103.96/4.92-5.06	71.08-71.70/3.94-4.09	71.68-72.18/3.73-3.83	74.72-74.83/3.56-3.65	67.88-68.38/3.51-3.66	62.49-62.58/3.62-3.80
2	aDGlcp	103.60-103.96/4.92-5.06	71.08-71.70/3.94-4.09	71.68-72.18/3.73-3.83	74.72-74.83/3.56-3.65	67.88-68.38/3.51-3.66	62.49-62.58/3.62-3.80
4	aDGalp	NMR TSV error 2: unequal length of 13C and 1H datasets
	aDManp	102.08/5.17	79.94/3.99	71.56/3.78	74.71/3.61	?/3.80	?/?

The spectrum also has 10 signals at unknown positions (not plotted).

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

[*]O[C@@H]1[C@@H](CO)O[C@H](O[C@H]2[C@@H](O)[C@H](O)[C@@H](CO)O[C@@H]2O[C@@H]2[C@@H](CO)O[C@H](O[C@@H]3[C@@H](CO)O[C@H](O[C@H]4[C@@H](O)[C@H](O)[C@@H](CO)O[C@@H]4O[C@@H]4[C@@H](CO)O[C@H](O[C@@H]5[C@@H](CO)O[C@H](O[C@@H]6[C@@H]([*])O[C@H](CO)[C@@H](O[C@H]7O[C@H](CO)[C@H](O)[C@H](O)[C@H]7O)[C@@H]6O)[C@H](O)[C@H]5O)[C@H](O)[C@H]4O)[C@H](O)[C@H]3O)[C@H](O)[C@H]2O)[C@H](O)[C@H]1O

1459.269 g/mol (C₅₄H₉₀R₂O₄₅, R = next and previous repeats, not counted in mol weight)

The objective of this study was to determine the effects of sophorolipids on several fungal and oomycete plant pathogens and the relationship between sophorolipids at different pH and antimicrobial activities. Sophorolipids had different solubility at different pH with a dramatic increase in solubility when pH was 6 or higher. Inhibition of mycelial growth of Phytophthora infestans by sophorolipids was affected by pH values, showing that when the pH value was higher, the inhibition rate was lower. Sophorolipids inhibited spore germination and mycelial growth of several fungal and oomycete pathogens in vitro including Fusarium sp., F. oxysporum, F. concentricum, Pythium ultimum, Pyricularia oryzae, Rhizoctorzia solani, Alternaria kikuchiana, Gaeumannomyces graminis var. tritici and P. infestans and caused morphological changes in hyphae by microscope observation. Sophorolipids reduced β-1,3-glucanase activity in mycelia of P. infestans. In greenhouse studies, foliar application of sophorolipids at 3 mg/ml reduced severity of late blight of potato caused by P. infestans significantly. Sophorolipids influenced spore germination and hyphal tip growth of several plant pathogens and pH solubility of sophorolipids had an effect on their efficacy. Application of sophorolipids reduced late blight disease on potato under greenhouse conditions. The findings indicated that sophorolipids have the potential to be developed as a convenient and easy-to-use formulation for managing plant diseases.

plant pathogen, sophorolipids, late blight of potato, Phytophthora infestans, pH solubility

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

R1 = LIP
[1*]O[C@@H]1O[C@H](COC(C)=O)[C@@H](O)[C@H](O)[C@H]1O[C@@H]1O[C@H](COC(C)=O)[C@@H](O)[C@H](O)[C@H]1O

425.363 g/mol (C₁₆H₂₅RO₁₃, R = residue superclass(es), not counted in mol weight)

The objective of this study was to determine the effects of sophorolipids on several fungal and oomycete plant pathogens and the relationship between sophorolipids at different pH and antimicrobial activities. Sophorolipids had different solubility at different pH with a dramatic increase in solubility when pH was 6 or higher. Inhibition of mycelial growth of Phytophthora infestans by sophorolipids was affected by pH values, showing that when the pH value was higher, the inhibition rate was lower. Sophorolipids inhibited spore germination and mycelial growth of several fungal and oomycete pathogens in vitro including Fusarium sp., F. oxysporum, F. concentricum, Pythium ultimum, Pyricularia oryzae, Rhizoctorzia solani, Alternaria kikuchiana, Gaeumannomyces graminis var. tritici and P. infestans and caused morphological changes in hyphae by microscope observation. Sophorolipids reduced β-1,3-glucanase activity in mycelia of P. infestans. In greenhouse studies, foliar application of sophorolipids at 3 mg/ml reduced severity of late blight of potato caused by P. infestans significantly. Sophorolipids influenced spore germination and hyphal tip growth of several plant pathogens and pH solubility of sophorolipids had an effect on their efficacy. Application of sophorolipids reduced late blight disease on potato under greenhouse conditions. The findings indicated that sophorolipids have the potential to be developed as a convenient and easy-to-use formulation for managing plant diseases.

plant pathogen, sophorolipids, late blight of potato, Phytophthora infestans, pH solubility

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

R1 = LIP
[*][1*]O[C@@H]1O[C@H](COC(C)=O)[C@@H](O)[C@H](O)[C@H]1O[C@@H]1O[C@H](COC(C)=O)[C@@H](O[*])[C@H](O)[C@H]1O

424.355 g/mol (C₁₆H₂₄R₃O₁₃, R = next and previous repeats / residue superclass(es), not counted in mol weight)

Sophorolipids are biomolecules with great potential to be explored in the food industry due to their efficient antimicrobial activity. Therefore, in this study, sophorolipids were produced by Starmerella bombicola, structurally characterized and applied as a sanitizing agent against the foodborne fungi Aspergillus flavus, Aspergillus melleus, Aspergillus ochraceus, Aspergillus parasiticus, Aspergillus niger, Fusarium oxysporum, Botrytis cinerea and Rhizopus spp. The sophorolipids production in the bioreactor was 67 g/L with a productivity of 0.56 g/L/h at 120 h. The predominant structure in the sophorolipids was the lactonic form, which was effective in the inhibition of all tested food spoilage fungi. Sophorolipids constitute a new possibility as an innovative sanitizing agent, controlling the microbial spoilage of foods and enhancing food safety.

antimicrobial activity, biosurfactant, foodborne pathogens, fungal mycelial inhibition

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

[*]O[C@@H]1[C@@H](CO)O[C@@H](O[C@@H]2[C@@H](O)[C@H](O)[C@@H](CO)O[C@H]2OC(C)CCCCCC/C=C\CCCCCCCC([*])=O)[C@H](O)[C@H]1O

604.734 g/mol (C₃₀H₅₂R₂O₁₂, R = next and previous repeats, not counted in mol weight)