Structural characterization and hepatoprotective activity of exopolysaccharide from Bacillus velezensis SN-1.

BACKGROUND: Exopolysaccharide biopolymers produced by microorganisms are crucial to the environment. They contribute to areas such as the health and bionanotechnology sectors, food and cosmetic industries as gelling agents, and environmental sector as flocculants owing to their biodegradability and non-toxic nature. The current study aimed to isolate the fraction of released exopolysaccharide (rEPS) by Bacillus velezensis SN-1 from Chinese Da-Jiang. RESULTS: The weighted average molecular weight of the major isolated component, rEPS-2, was 202 kDa, and its monosaccharide composition included mannose, glucose, and galactose at a molar ratio of 0.38:0.30:0.32. Further, the rEPS-2 was characterized using methylation analysis and one-dimensional/two-dimensional nuclear magnetic resonance (1D/2D NMR) spectroscopy. In vivo hepatoprotective effects indicated that rEPS-2 could alleviate carbon tetrachloride (CCl4 )-induced liver injury in mice by lowering the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and the malondialdehyde (MDA) levels. Furthermore, rEPS-2 can increase the expression of antioxidant genes HO-1, GCLC and NQO1 in the Nrf2/ARE signaling pathway, thereby increasing the activity of antioxidant enzymes superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and reduced catalase (CAT) in liver cells. Furthermore, the rEPS-2 can be used and modulate the gut microbiota of mice with liver injury caused by CCl4 . CONCLUSIONS: These results suggest that rEPS-2 has promising potential to serve as hepatoprotective agents. © 2022 Society of Chemical Industry.

Structural characterization and antioxidant potential of a novel exopolysaccharide produced by Bacillus velezensis SN-1 from spontaneously fermented Da-Jiang.

The aim of this study was to characterize the exopolysaccharide (EPS) produced by Bacillus velezensis SN-1 (B. velezensis SN-1) (EPS-SN-1), which was isolated from the fermented Da jiang. The microbe made crude exopolysaccharides EPS-SN-1 was produced throughout the bacterial growth period, and the highest yield (2.7 g/L) was obtained with sucrose as the carbon source. As per high performance liquid chromatography (HPLC), EPS-SN-1 is a heteropolysaccharide consisting of glucose, mannose and fructose, with a high molecular weight of 2.21 × 105 Da. FTIR spectra further indicated the presence of hydroxyl and carbonyl groups, and NMR analysis confirmed both α- and ß-glycosidic bonds. Furthermore, differential scanning calorimetry (DSC) showed that EPS-SN-1 has high thermal stability with fusion point of 270.7 °C. Finally, EPS-SN-1 demonstrated strong antioxidant capacity via its ability to scavenge hydroxyl radical (•OH), 1,1-diphenyl-2-picrylhydrazyl (DPPH•) radical, ABTS radical (ABTS•+) and oxygen radical (O2-•). Taken together, EPS-SN-1 is a promising natural antioxidant and probiotic with potential applications in the food industry.

Purification, characterization and antitumor activity of an exopolysaccharide produced by Bacillus velezensis SN-1.

A capsular polysaccharides (CPS) producer Bacillus velezensis SN-1 (B. velezensis SN-1) was isolated in Da-jiang, China. We used ultrasonic extraction to obtain CPS from a culture of B. velezensis SN-1 at a yield of 755 mg/L. Using gel permeation chromatography (GPC), CPS was separated into a single peak with a molecular weight of 1.46 × 105 Da. Its structures were characterized by gas chromatography (GC), methylation, Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). The CPS was identified as a polysaccharide with a highly branched main chain of mannose with (1 â†’ 3) connections. Moreover, our results revealed that CPS has the capacity to scavenge DPPH radical, hydroxyl radical, ABTS radical and oxygen radical in a manner that relied on concentration. Anti-neoplastic analysis showed that CPS displayed significant anti-tumor activity towards HepG-2 tumor cells. Above findings indicate that CPS generated by B. velezensis SN-1 may be adapted for use as a natural antioxidant in foodstuffs and as an anti-tumor drug.