Potassium Alginate Oligosaccharides Alter Gut Microbiota, and Have Potential to Prevent the Development of Hypertension and Heart Failure in Spontaneously Hypertensive Rats.

Food-derived oligosaccharides show promising therapeutic potential in lowering blood pressure (BP), but the mechanism is poorly understood. Recently, the potential role of gut microbiota (GM) in hypertension has been investigated, but the specific GM signature that may participate in hypertension remains unclear. To test the potassium alginate oligosaccharides (PAO) mechanism in lowering BP and specific microbial signature changes in altering GM, we administered various dosages of PAO in 40 spontaneously hypertensive rats for a duration of six weeks. We analyzed BP, sequenced the 16S ribosomal DNA gene in the cecum content, and gathered RNA-seq data in cardiac tissues. We showed that the oral administration of PAO could significantly decrease systolic BP and mean arterial pressure. Transcriptome analyses demonstrated that the protective effects of developing heart failure were accompanied by down-regulating of the Natriuretic Peptide A gene expression and by decreasing the concentrations of angiotensin II and atrial natriuretic peptide in plasma. In comparison to the Vehicle control, PAO could increase the microbial diversity by altering the composition of GM. PAO could also decrease the ratio of Firmicutes to Bacteroidetes by decreasing the abundance of Prevotella and Phascolarctobacterium bacteria. The favorable effect of PAO may be added to the positive influence of the abundance of major metabolites produced by Gram-negative bacteria in GM. We suggest that PAO caused changes in GM, and thus, they played an important role in preventing the development of cardiovascular disease.

[Pollution Characteristics of Perfluorinated Alkyl Substances (PFASs) in Seawater, Sediments, and Biological Samples from Jiaozhou Bay, China].

In order to explore the pollution levels and characteristics of perfluorinated alkyl substances (PFASs), seawater, sediment, and Ruditapes philippinarum samples were collected near the Jiaozhou Bay coast in April 2018. All samples were analyzed by using the high performance liquid chromatography-mass spectrometry method to determine the content of 35 types of PFASs. The results showed that 12 different PFASs were tested in the seawater with ∑PFASs concentrations of 21.1-38.0 ng·L-1; 10 types of PFASs were detected in sediments, with ∑PFASs content (dry weight) ranging from 0.459 to 1.20 µg·kg-1; 19 types of PFASs were measured in Ruditapes philippinarum, with ∑PFASs content (dry weight) of 15.5-27.5 µg·kg-1. Compared with other areas reported in the literature, the total pollution of Jiaozhou Bay was at medium or high levels. In addition, perfluorooctanoic acid (PFOA) was the dominant PFAS in the seawater, sediments, and Ruditapes philippinarum with a detection rate of 100%. 6:2 fluorotelomer phosphate diester (6:2 diPAP) was observed for the first time in seawater and sediments from Jiaozhou Bay and had the highest detection frequency and concentration of the precursor. Perfluorooctanesulfonamide (PFOSA) was the main precursor in Ruditapes philippinarum, of which the detection rate was 93.8%. Moreover, the organic carbon normalized sediment-water distribution coefficient (lg KOC) values were 5.24-6.37 and increased with an increase in carbon chain length. The bioaccumulation factors (lg BAF) and field-based biota-sediment accumulation factors (lg BSAF) were 2.53-4.32 and 1.30-2.50, respectively. The lg BAF values positively correlated with the carbon chain length, whereas the lg BSAF values decreased with an increase in the carbon chain length (C8-C13).

Rational Design of Alginate Lyase from Microbulbifer sp. Q7 to Improve Thermal Stability.

Alginate lyase degrades alginate by the ß-elimination mechanism to produce oligosaccharides with special bioactivities. The low thermal stability of alginate lyase limits its industrial application. In this study, introducing the disulfide bonds while using the rational design methodology enhanced the thermal stability of alginate lyase cAlyM from Microbulbifer sp. Q7. Enzyme catalytic sites, secondary structure, spatial configuration, and molecular dynamic simulation were comprehensively analyzed. When compared with cAlyM, the mutants D102C-A300C and G103C-T113C showed an increase by 2.25 and 1.16 h, respectively, in half-life time at 45 °C, in addition to increases by 1.7 °C and 0.4 °C in the melting temperature, respectively. The enzyme-specific activity and kcat/Km values of D102C-A300C were 1.8- and 1.5-times higher than those of cAlyM, respectively. The rational design strategy that was used in this study provides a valuable method for improving the thermal stability of the alginate lyase.

Evaluation of Prebiotic Potential of Three Marine Algae Oligosaccharides from Enzymatic Hydrolysis.

Alginate oligosaccharides (AlgO), agarose oligosaccharides (AO), and κ-carrageenan oligosaccharides (KCO) were obtained by specific enzymatic hydrolysis method. The molecular weight distributions of the three oligosaccharides were 1.0⁻5.0 kDa, 0.4⁻1.4 kDa, and 1.0⁻7.0 kDa, respectively. The culture medium was supplemented with the three oligosaccharides and fermented by pig fecal microbiota in vitro, for 24 h. Each oligosaccharide was capable of increasing the concentration of short-chain fatty acids (SCFAs), especially butyric acid, and altering the microbiota composition. Linear discriminant analysis effect size (LEfSe) analysis results showed that the opportunistic pathogenic bacteria Escherichia, Shigella, and Peptoniphilus, were significantly decreased in AlgO supplemented medium. AO could improve the gut microbiota composition by enriching the abundance of Ruminococcaceae, Coprococcus, Roseburia, and Faecalibacterium. Besides, KCO could increase the abundance of SCFA microbial producers and opportunistic pathogenic flora. Therefore, these results indicate that AlgO and AO can be used as gut microbial regulators and can potentially improve animal/human gastrointestinal health and prevent gut disease, whereas the physiological function of KCO needs further evaluation.

The antitumor and antioxidative activities of polysaccharides isolated from Isaria farinosa B05.

The water-soluble intra-polysaccharides WIPS1 and water-soluble extra-polysaccharides WEPS1 were isolated from Isaria farinosa B05 through ethanol precipitation and gel permeation chromatography (GPC). Their characteristics were determined by chemical analysis, gas chromatography, GPC and IR spectroscopy. The results show that WIPS1 contained 90.3% carbohydrate, 8.00% uronic acid, 7.15% protein and three kinds of monosaccharides including mannose, galactose and glucose with a molar ratio of 8.0:4.8:1.0. WEPS1 contained 93.4% carbohydrate, 8.06% uronic acid, 4.40% protein and three kinds of monosaccharides including mannose, galactose and glucose with a molar ratio of 21.6:4.7:1.0. WIPS1 and WEPS1 had a molecular weight of 42 and 208kDa, respectively. The in vivo tests in mice indicate that WIPS1 and WEPS1 had significant antitumor and antioxidative activities to some extent.