Activation of Macrophages by Exopolysaccharide Produced by MK1 Bacterial Strain Isolated from Neungee Mushroom, Sarcodon aspratus

Effect of monosaccharide composition and proportion on the bioactivity of polysaccharides: A review

Polysaccharides have been widely used in pharmaceutical and food industries due to their diverse bioactivity, high safety, and few or no side effects. However, inability to quickly produce, screen, and synthesize bioactive polysaccharides is the limiting factor for their development and application. Structural features determine and influence the bioactivity of polysaccharides. Among them, monosaccharide is the basic unit of polysaccharide, which not only affects electrification, functional group, and bioactivity of polysaccharide but also is one of the simplest polysaccharide indexes to be detected. At present, effects of monosaccharide composition and proportion on anti-inflammatory, antioxidant, antitumor, immunomodulatory, antibacterial, and prebiotic activities of polysaccharides are reviewed. Further problems need to be considered during regulation and analysis of monosaccharide composition and proportion of polysaccharides. Overall, present work will provide help and reference for production, development, and structure-function investigation of polysaccharides based on their monosaccharide.

In vitro gastrointestinal digestion of Lentinus squarrosulus powder and impact on human fecal microbiota

Humans have long-used mushrooms as food and medicine, but digestion and colonic fermentation of most mushrooms, including Lentinus squarrosulus is markedly unknown. Here, nutritional profile, digestion and colonic fermentation of L. squarrosulus powder (LP) were determined. The powder contained mainly carbohydrate and protein. SEM and F-TIR analysis of the resistant hydrolysate (RH) revealed that the structure and ratio of carbohydrate and protein components were altered, and released known immunomodulation agents; beta-glucans and mannose. Both LP and RH promoted selected probiotic bacteria, especially Bifidobacterium strains. Using fecal microbiota of five volunteers (V1, V2, V3, V4 and V5), RH stimulated the microbiota of all used volunteers, via decreasing the ratio of Firmicutes/Bacteroidetes ranging from 1.3 to 8.2 times. Also, RH increased the relative abundance of vital immunomodulators; Bacteroides, Bifidobacterium, Clostridium cluster XIVa and IV, and Sutterella. Additionally, RH fermentation enriched the content of branch-chain fatty acids (BCFA) and short-chain fatty acids (SCFA), indicating protein and carbohydrate usage. Notably, propionic and butyric acids were abundant in V1, V2 and V3, while in V4 and V5, acetic and butyric acids were most enriched. Suggesting L. squarrosulus as functional mushroom to improve health and prevent diseases by enhancing gut health.

Structure Differences of Water Soluble Polysaccharides in Astragalus membranaceus Induced by Origin and Their Bioactivity

Astragalus membranaceus is a functional food with multiple bioactivities. It presents differentiated health benefits due to origins. Polysaccharides (APS) are the leading bioactive macromolecules of A. membranaceus, which are highly related to its health benefits. However, the effect of origin on the structural characteristics of APSs remains unclear. In this work, polysaccharides from four origins were isolated and identified by NMR. The results showed APSs of four origins had identical monosaccharide composition and glycosidic linkage. Rhamnogalacturonan II pectins and α-(1→4)-glucan were the dominant polysaccharides. However, the level of methyl ester in pectins varied to a large extent. The molecular weight profiles of APSs were also different. Inner Mongolia APS had the largest percentage of 20-40 kDa polysaccharides. Molecular weight and methyl ester level were two important parameters determining the difference of APSs from four origins. These results were helpful to recognize the origin-related quality of A. membranaceus.

Inflammatory potential of monospecies biofilm matrix components

AIM

To assess the inflammatory potential of biofilm matrix constituents of Enterococcus faecalis and Pseudomonas aeruginosa monospecies biofilms on macrophages.

METHODOLOGY

In vitro biofilms of E. faecalis and P. aeruginosa were grown (7 days) in aerobic and anaerobic conditions. The biofilm matrix components: exopolysaccharides (EPS) and extracellular DNA (eDNA) were extracted and quantified. The inflammatory potential of EPS and eDNA was assessed on macrophage cell lines (RAW 267.4) using nitric oxide (NO), and enzyme-linked immunosorbent assay for tumour necrosis factor (TNF-α) and interleukin-6 (IL-6) expressions. LPS from P. aeruginosa and planktonic bacteria were positive controls. One-way analysis of variance and the Tukey post hoc test were used for statistical analysis.

RESULTS

Extracted EPS from both biofilm strains was associated with higher levels than eDNA in both growth conditions (P < 0.05). The biofilm components had less inflammatory potential compared to planktonic bacteria and LPS. EPS produced higher levels of inflammatory response compared to eDNA for both strains (P < 0.05). IL-6 and TNF-α, and NO expression showed no difference for E. faecalis EPS (P ≥ 0.05). In contrast, P. aeruginosa EPS and eDNA had significant levels of IL-6 compared to TNF-α and NO (P < 0.05).

CONCLUSIONS

Monospecies biofilm matrix EPS and eDNA from the bacterial strains tested had the ability to induce a low-grade inflammatory response when compared to planktonic bacteria and LPS. This study highlights the potential of biofilm matrix/components, devoid of bacteria to induce low-grade chronic inflammation.

Escherichia coli attachment to model particulates: The effects of bacterial cell characteristics and particulate properties

E. coli bacteria move in streams freely in a planktonic state or attached to suspended particulates. Attachment is a dynamic process, and the fraction of attached microorganisms is thought to be affected by both bacterial characteristics and particulate properties. In this study, we investigated how the properties of cell surfaces and stream particulates influence attachment. Attachment assays were conducted for 77 E. coli strains and three model particulates (ferrihydrite, Ca-montmorillonite, or corn stover) under environmentally relevant conditions. Surface area, particle size distribution, and total carbon content were determined for each type of particulate. Among the three particulates, attachment fractions to corn stover were significantly larger than the attachments to 2-line ferrihydrite (p-value = 0.0036) and Ca-montmorillonite (p-value = 0.022). Furthermore, attachment to Ca-montmorillonite and corn stover was successfully modeled by a Generalized Additive Model (GAM) using cell characteristics as predictor variables. The natural logarithm of the net charge on the bacterial surface had a significant, positive, and linear impact on the attachment of E. coli bacteria to Ca-montmorillonite (p-value = 0.013), but it did not significantly impact the attachment to corn stover (p-value = 0.36). The large diversities in cell characteristics among 77 E. coli strains, particulate properties, and attachment fractions clearly demonstrated the inadequacy of using a static parameter or linear coefficient to predict the attachment behavior of E. coli in stream water quality models.

Bioactive Mushroom Polysaccharides: A Review on Monosaccharide Composition, Biosynthesis and Regulation

Mushrooms are widely distributed around the world and are heavily consumed because of their nutritional value and medicinal properties. Polysaccharides (PSs) are an important component of mushrooms, a major factor in their bioactive properties, and have been intensively studied during the past two decades. Monosaccharide composition/combinations are important determinants of PS bioactivities. This review summarizes: (i) monosaccharide composition/combinations in various mushroom PSs, and their relationships with PS bioactivities; (ii) possible biosynthetic pathways of mushroom PSs and effects of key enzymes on monosaccharide composition; (iii) regulation strategies in PS biosynthesis, and prospects for controllable biosynthesis of PSs with enhanced bioactivities.

E. coli Surface Properties Differ between Stream Water and Sediment Environments

The importance of E. coli as an indicator organism in fresh water has led to numerous studies focusing on cell properties and transport behavior. However, previous studies have been unable to assess if differences in E. coli cell surface properties and genomic variation are associated with different environmental habitats. In this study, we investigated the variation in characteristics of E. coli obtained from stream water and stream bottom sediments. Cell properties were measured for 77 genomically different E. coli strains (44 strains isolated from sediments and 33 strains isolated from water) under common stream conditions in the Upper Midwestern United States: pH 8.0, ionic strength 10 mM and 22°C. Measured cell properties include hydrophobicity, zeta potential, net charge, total acidity, and extracellular polymeric substance (EPS) composition. Our results indicate that stream sediment E. coli had significantly greater hydrophobicity, greater EPS protein content and EPS sugar content, less negative net charge, and higher point of zero charge than stream water E. coli. A significant positive correlation was observed between hydrophobicity and EPS protein for stream sediment E. coli but not for stream water E. coli. Additionally, E. coli surviving in the same habitat tended to have significantly larger (GTG)₅ genome similarity. After accounting for the intrinsic impact from the genome, environmental habitat was determined to be a factor influencing some cell surface properties, such as hydrophobicity. The diversity of cell properties and its resulting impact on particle interactions should be considered for environmental fate and transport modeling of aquatic indicator organisms such as E. coli.

Evaluation of the angiogenic potency of a novel exopolysaccharide produced by the MK1 bacterial strain

Angiogenesis is an essential physiological step in wound healing and other regenerative processes. Here, we evaluated the angiogenic properties of an exopolysaccharide (EPS) secreted by MK1 (MK1-EPS), a novel bacterial strain isolated from Neungee mushrooms. MK1-EPS significantly increased human umbilical vein endothelial cell (HUVEC) proliferation, migration, and vascular tube formation. MK1-EPS enhanced the phosphorylation of extracellular signal-related kinase (ERK), c-Jun N-terminal kinase (JNK), and p38, which are mitogen-activated protein kinases. In addition, the expression of p21 and intercellular adhesion molecule 1 (ICAM1), and phosphorylation of signal transducer and activator of transcription 3 (STAT3), but not of protein kinase B (AKT), were increased. Specific inhibitors of p38 (SB203580), ERK (PD98059), and JNK (SP600125) inhibited MK1-EPS-induced HUVEC proliferation, tube formation, and cell migration, and partially attenuated MKI-EPS-induced expression of p21 and ICAM1, and STAT3 phosphorylation. After surgical implantation into rabbit calvarial bone defects, new blood vessel formation was significantly higher with MK1-EPS composite bone granules than with granules alone, and new bone formation increased significantly. Therefore, MK1-EPS induces angiogenesis and may have potential for use as a bone regeneration agent in bone tissue engineering applications.

Exopolysaccharide produced by Enterobacter sp. YG4 reduces uranium induced nephrotoxicity

Uranium nephrotoxicity is a health concern with very few treatment options. Bacterial exopolysaccharides (EPS) possess multiple biological activities and appear as prospective candidates for treating uranium nephrotoxicity. This study focuses on the ability of an EPS produced by a bacterial strain Enterobacter sp. YG4 to reduce uranium nephrotoxicity in vivo. This bacterium was isolated from the gut contents of a slug Laevicaulis alte (Férussac). Based on the aniline blue staining reaction and infrared spectral analysis, the EPS was identified as β-glucan and its molecular weight was 11.99×10(6)Da. The EPS showed hydroxyl radical scavenging ability and total antioxidant capacity in vitro. To assess the protection provided by the EPS against uranium nephrotoxicity, a single dose of 2mg/kg uranyl nitrate was injected intraperitoneally to albino Wistar rats. As intervention, the EPS was administered orally (100mg/kg/day) for 4 consecutive days. The rats were sacrificed on the fifth day and analyses were conducted. Increased serum creatinine and urea nitrogen levels and histopathological alterations in kidneys were observed in uranyl nitrate treated animals. All these alterations were reduced with the administration of Enterobacter sp. YG4 EPS, emphasizing a novel approach in treating uranium nephrotoxicity.