Purification and characterization of a highly viscous polysaccharide produced by Paenibacillus strain

Glycerol-driven adaptive evolution for the production of low-molecular-weight Welan gum: Characterization and activity evaluation

Through adaptive laboratory evolution (ALE) of Sphingomonas sp. ATCC 31555, fermentation for production of low-molecular-weight welan gum (LMW-WG) was performed using glycerol as sole carbon source. During ALE, GPC-MALS analysis revealed a gradual decrease in WG molecular weight with the increase of adaptation cycles, accompanied by changes in solution conformation. LMW-WG was purified and structurally analyzed using GPC-MALS, monosaccharide composition analysis, infrared spectroscopy, NMR analysis, atomic force microscopy, and scanning electron microscopy. Subsequently, LMW-WG obtains hydration, transparency, antioxidant activity, and rheological properties. Finally, an in vitro simulation colon reactor was used to evaluate potential prebiotic properties of LMW-WG as dietary fiber. Compared with WG produced using sucrose as substrate, LMW-WG exhibited a fourfold reduction in molecular weight while maintaining moderate viscosity. Structurally, L-Rha nearly completely replaced L-Man. Furthermore, LMW-WG demonstrated excellent hydration, antioxidant activity, and high transparency. It also exhibited resistance to saliva and gastrointestinal digestion, showcasing a favorable colonization effect on Bifidobacterium, making it a promising symbiotic agent.

Valorization of cell wall polysaccharides extracted from Liubao brick tea residues: chemical, structural, and hypoglycemic properties

BACKGROUND

Tea dregs, typically generated during the production of instant tea or tea beverages, have conventionally been regarded as waste material and routinely discarded. Nevertheless, contemporary research endeavors are concentrating on discovering efficient methods for utilizing the potential of this discarded resource.

RESULTS

In this study, we employed a sequential extraction method using chemical chelating agents to extract and isolate four distinct cell wall polysaccharides, designated as CWTPS-1 through CWTPS-4, from the tea dregs of Liubao brick tea. A comprehensive investigation into their physicochemical, structural, and hypoglycemic properties was conducted. The analysis of chemical composition and physicochemical characteristics revealed that all four CWTPSs were characterized as acidic polysaccharides, albeit with varying chemical compositions and physicochemical attributes. Specifically, the xyloglucan fractions, CWTPS-3 and CWTPS-4, were found to be rich in glucose and xylose, displaying a more uniform molecular weight distribution, greater structural stability, and a more irregular surface compared to the others. Moreover, they exhibited a higher diversity of monosaccharide residues. Importantly, our research unveiled that all four CWTPSs exhibited the capacity to modulate key glucose-regulated and antioxidant enzyme activities within HepG2 cells via the IRS-1-PI3K/AKT signaling pathway, thereby ameliorating cellular insulin resistance. Furthermore, our correlation analysis highlighted significant associations between monosaccharide composition and neutral sugar content with the observed hypoglycemic activity of CWTPSs.

CONCLUSION

This study highlights the potential of utilizing tea dregs as a valuable resource, making a significant contribution to the advancement of the tea industry. Furthermore, CWTPS-4 exhibits promising prospects for further development as a functional food ingredient or additive. © 2024 Society of Chemical Industry.

Exopolysaccharides of Paenibacillus polymyxa: A review

Paenibacillus polymyxa (P. polymyxa) is a member of the genus Paenibacillus, which is a rod-shaped, spore-forming gram-positive bacterium. P. polymyxa is a source of many metabolically active substances, including polypeptides, volatile organic compounds, phytohormone, hydrolytic enzymes, exopolysaccharide (EPS), etc. Due to the wide range of compounds that it produces, P. polymyxa has been extensively studied as a plant growth promoting bacterium which provides a direct benefit to plants through the improvement of N fixation from the atmosphere and enhancement of the solubilization of phosphorus and the uptake of iron in the soil, and phytohormones production. Among the metabolites from P. polymyxa, EPS exhibits many activities, for example, antioxidant, immunomodulating, anti-tumor and many others. EPS has various applications in food, agriculture, environmental protection. Particularly, in the field of sustainable agriculture, P. polymyxa EPS can be served as a biofilm to colonize microbes, and also can act as a nutrient sink on the roots of plants in the rhizosphere. Therefore, this paper would provide a comprehensive review of the advancements of diverse aspects of EPS from P. polymyxa, including the production, extraction, structure, biosynthesis, bioactivity and applications, etc. It would provide a direction for future research on P. polymyxa EPS.

Hemoadhican, a Tissue Adhesion Hemostatic Material Independent of Blood Coagulation

Uncontrolled hemorrhage is a leading cause of death, emphasizing the need for novel hemostatic agents. Here, a novel hemostatic polysaccharide hemoadhican (HD) is screened out by analyzing the rheological properties of screened material mixed blood sludges, which is prepared by mixing polysaccharide granules and whole blood to mimic the coagulation in vitro. HD is produced by a bacterial isolate Paenibacillus sp.1229, and the repeating units of HD are →)-α-L-Rhap-(1→3)-β-D-Glcp-(1→4)[4,6-ethylidene-α-D-Galp-(1→4)-α-D-Glcp-(1→3)]-α-D-Manp-(1→. Compared to chitosan and celox, HD achieves more effective hemostasis in animal models with mouse and rat femoral arteries, rat carotid arteries, and rabbit femoral arteries. Especially, HD maintains an excellent hemostatic capability in animals with heparin-induced hemorrhage diathesis. In vitro experiments show HD granules can quickly absorb a small amount of blood component to create a hemophobic blood sludge resistant to high pressure. The blood sludge firmly adheres to damaged tissue and efficiently repels blood. In vitro experiments show that HD does not actively trigger blood coagulation cascade and is independent of blood conditions including heparin treatment. In addition, HD moisturizes wounds and accelerates wound healing, exhibiting excellent biodegradability, and hemocompatibility. The results indicate that HD is a promising hemostatic material for treating traumatic hemorrhages and uncontrollable surgical bleeding.

Genomic Insights and Functional Analysis Reveal Plant Growth Promotion Traits of Paenibacillus mucilaginosus G78

Paenibacillus mucilaginosus has widely been reported as a plant growth-promoting rhizobacteria (PGPR). However, the important genomic insights into plant growth promotion in this species remain undescribed. In this study, the genome of P. mucilaginosus G78 was sequenced using Illumina NovaSeq PE150. It contains 8,576,872 bp with a GC content of 58.5%, and was taxonomically characterized. Additionally, a total of 7337 genes with 143 tRNAs, 41 rRNAs, and 5 ncRNAs were identified. This strain can prohibit the growth of the plant pathogen, but also has the capability to form biofilm, solubilize phosphate, and produce IAA. Twenty-six gene clusters encoding secondary metabolites were identified, and the genotypic characterization indirectly proved its resistant ability to ampicillin, bacitracin, polymyxin and chloramphenicol. The putative exopolysaccharide biosynthesis and biofilm formation gene clusters were explored. According to the genetic features, the potential monosaccharides of its exopolysaccharides for P. mucilaginosus G78 may include glucose, mannose, galactose, fucose, that can probably be acetylated and pyruvated. Conservation of the pelADEFG compared with other 40 Paenibacillus species suggests that Pel may be specific biofilm matrix component in P. mucilaginosus. Several genes relevant to plant growth-promoting traits, i.e., IAA production and phosphate solubilization are well conserved compared with other 40 other Paenibacillus strains. The current study can benefit for understanding the plant growth-promoting traits of P. mucilaginosus as well as its potential application in agriculture as PGPR.

Characterization and bioactivity analysis of a heteropolysaccharide purified from Paenibacillus edaphicus strain UJ1

Many polysaccharides produced by Paenibacillus spp. have attractive properties, such as rheological modification and immunomodulation. However, properties of P. edaphicus polysaccharides are not understood sufficiently. Here, the polysaccharide (PUM) was obtained from P. edaphicus strain UJ1 by batch fermentation, and the chemical characteristics, rheological and anti-inflammatory properties of PUM and its sulfate derivative (PUM-S) were investigated. The results indicated that PUM was a typical shear-thinning biopolymer with an estimated weight average molecular weight of 2.45 × 10⁷ Da. PUM molecule consisted of D-Man, D-GlcA, D-Glc, D-Gal, and L-Fuc with the molar ratio of 3.00:1.07:3.21:0.81:0.76. It had the backbone → 3)-β-D-Man-(1 → 3)-β-D-Glc-(1 → 3)-β-D-Man-(1 → 3)β-D-Glc-(1 → 4)-β-D-GlcA-(1 → 3)-β-D-Man-(1 → and two side chains, namely, pyruvoyl-Glc-(1→ and β-L-Fuc-(1 → 3)-β-D-Gal-(1→. Moreover, PUM-S was prepared by SO₃-pyridine method and had the weight average molecular weight of 1.42 × 10⁵ Da. The bioactivity of PUM and PUM-S was analyzed in vitro in RAW 264.7 cells. The results indicated that both PUM and PUM-S facilitated cell proliferation at 50-500 μg/mL. Besides, PUM-S showed potential anti-inflammatory effect in the LPS-induced cells. According to transcription and molecular dynamics analyses, PUM-S expressed its activity probably by interacting with the Toll-like receptor 4. In general, P. edaphicus produced a polysaccharide with new chemical structure and promising rheological and bioactive properties.

Transcriptomic and metabolomic profiling of a Rhodotorula color mutant to improve its lipid productivity in fed-batch fermentation

Lipids produced by oleaginous microorganisms enrich the supply of feedstock for bio-fuel. In this study, a mutant (Mut) obtained by UV-nitrosoguanidine mutagenesis turned its colony color from orange-red to light-yellow and showed higher lipid productivity at 37 °C than the original strain Rhodotorula sp. U13N3 (Rht) in the glycerol medium. The metabolic changes between Mut and Rht in batch fermentation were investigated by transcriptomic and metabolomic profiling at the biomass accumulation (30 h) and lipid production (96 h) stages. The average base number in each strain was 5.80 × 10⁹ ± 0.38 × 10⁹ bp (mean ± SD) with 62.43% ± 0.13% GC ratio, and 7499 unigenes were assembled after Illumina sequencing. Moreover, 33 metabolites were quantified by ¹H NMR-based profiling. The multi-omics results demonstrated that Mut showed increased glycerol transport and utilization capabilities especially at the first stage (30 h). Then the carbon flux shifted from the TCA cycle to lipid production (96 h). The increased lipid productivity of Mut was partially attributed to the down-regulation of mannitol biosynthesis. However, the mechanism for color change was elusive. At 96 h, the low level of cytosol glycerol probably restricted the lipid production. As a result, supplementation of glycerol in fed-batch fermentation remarkably improved the biomass, lipid production, and lipid content to 34.60 g/L, 25.72 g/L, and 74.3% (w/w dcw), respectively. The cell morphology implied that excessively prolonging the fermentation time was detrimental to the final lipid yield due to cell breakage. In conclusion, the Rhodotorula mutant provided a candidate strain for lipid production with glycerol as the carbon source.

Bacterial exopolysaccharides: Chemical structures, gene clusters and genetic engineering

In recent decades, the composition, structure, biosynthesis, and function of bacterial extracellular polysaccharides (EPS) have been extensively studied. EPS are synthesized through different biosynthetic pathways. The genes responsible for EPS synthesis are usually clustered on the genome or large plasmids of bacteria. Generally, different EPS synthesis gene clusters direct the synthesis of EPS with different chemical structures and biological activities. A better understanding of the gene functions involved in EPS biosynthesis is critical for the production of EPS with special biological activities. Genetic engineering methods are usually used to study EPS synthesis related genes. This review organizes the available information on EPS, including their structures, synthesis of related genes, and highlights the research progress of modifying EPS gene clusters through gene-editing methods.

Structural analysis and potential anti-tumor activity of Sporisorium reilianum (Fries) polysaccharide

A neutral polysaccharide WM-NP-60 was successfully isolated and purified from a phytopathogenic fungus Sporisorium reilianum (Fries). The characteristics and potential antitumor activities of WM-NP-60 were studied. WM-NP-60 was a water-soluble polysaccharide. The molecular weight of WM-NP-60 was 15.6 kDa. The main chain of WM-NP-60 was composed of β-1,6-D-Glcp and its side chains were β-1,3-D-Glcp. The side chains bound to the main chain with glycosyl groups at the C-3 positions. Gal might be attached to the backbone as a side chain or bound to the linear β-1,3-D-Glcp side chain. WM-NP-60 could inhibit the proliferation of HepG2 and SGC7901 cells in a dose-dependently manner. In addition, it was found that WM-NP-60 triggered the HepG2 and SGC7901 cell cycle arrest at the G₁ phase and induced apoptosis of HepG2 and SGC7901 cells. Taken together, these results suggested that WM-NP-60 possessed a tumor-suppressive activity and might be regarded as a potential natural anti-tumor drug.

Anti-inflammatory activity and structural identification of a sulfated polysaccharide CLGP4 from Caulerpa lentillifera

In the present study, the in vitro anti-inflammatory activity of four purified polysaccharides (CLGP1, CLGP2, CLGP3 and CLGP4) extracted from edible green algae Caulerpa lentillifera was evaluated. As a result, CLGP4 exhibited more effectively inhibitory effect on LPS-induced HT29 cells, including reducing the production of IL-1β, TNF-α, SIgA and mucin2, and decreasing the expression of IL-1β and TNF-α. According to the results, CLGP4 showed a better anti-inflammatory effect, might highly related to the presence of sulfate groups. Furthermore, the structure of CLGP4 was analyzed by methylation analysis, GC-MS and NMR spectroscopy. It was found that CLGP4 was a novel xylogalactomanan consisting of β-(1 → 4)-Man_p, →2,4)Man_p(1→, β-(1 → 2)-Man_p, β-(1 → 3)-Gal_p, β-(1 → 4)-Xyl_p, terminal β-Gal_p and terminal β-Xyl_p residues. Additionally, the sulfate groups were located on C-3 of →4)Xyl_p(1→, C-6 of →3)Gal_p(1→ and C-3 of →2)Man_p(1→. These results could enlarge the potential application of CLGP4 as functional ingredient to attenuate inflammation.