Evaluation of a Novel Phosphorylated Red Dragon Fruit Peel Pectin for Enhancement of Thermal Stability and Functional Activity.

Red dragon fruit peel, as a fruit waste, is rich in plant-based nutritional pectins that can be applied as food additives. The present study aims to characterize a novel phosphorylated red dragon fruit peel pectin (PRDFP-P) and to explore its functional activities. The thermal analysis, morphology analysis, antibacterial, antioxidant and antitumor activities of PRDFP-P were evaluated. The results showed that the phosphorylated derivative PRDFP-P had typical phosphate groups. Compared with the native red dragon fruit peel pectin (PRDFP), PRDFP-P possessed superior thermal stability and exhibited significant inhibition effects on Escherichia coli and Staphylococcus aureus. Moreover, the phosphate groups on the derivative PRDFP-P chains remarkably enhanced the scavenging ability of hydroxyl radicals and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals. In addition, PRDFP-P showed a significant inhibition effect on growth of human hepatic carcinoma cells (HepG2) and the IC50 value was determined to be 248.69 µg/mL (P < 0.05). Our results suggested that the phosphorylated derivative PRDFP-P might be potentially applied as stabilizing, thickening and gelling agents with functional activities in the food industry.

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.

Study on expression and action mode of recombinant alginate lyases based on conserved domains reconstruction.

Understanding the effect of conserved domains reconstruction of alginate lyases on action mode is essential for their application and in-depth study. We report the expression and action mode of recombinant alginate lyase (AlyM) and its conserved domain reconstruction forms (AlyMΔCBM, cAlyM, and AlyMΔ58C). The enzymatic activities of AlyM, AlyMΔCBM, cAlyM, and AlyMΔ58C were 61.77, 150.57, 388.97, and 308.21 U/mg, respectively. The transcription level of cAlyM was 49.89-fold of AlyM. cAlyM and AlyMΔ58C showed higher thermal stability than AlyM, indicating that the removal of F5_F8_type_C domain was beneficial for the increase of thermal stability. The enzymes were bifunctional alginate lyases and preferred polyG to polyM. The enzymes degraded alginate to produce unsaturated disaccharide, trisaccharide, and tetrasaccharide as the main end-products. Pentamannuronic acid and pentaguluronic acid were the smallest substrates that could be degraded by AlyM, with unsaturated trisaccharide/tetrasaccharide (40.61%/44.42%) and disaccharide/trisaccharide (10.57%/83.85%) as the main products, respectively. The action modes of enzymes remain unaffected after conserved domain reconstruction, but the affinity of AlyMΔ58C toward polyM increased. This study provides a new strategy for rational modification of alginate lyase based on conserved domain reconstruction.

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.

Improvement in caffeic acid and ferulic acid extraction by oscillation-assisted mild hydrothermal pretreatment from sorghum straws.

This work investigated the effect of oscillation-assisted hydrothermal process on extraction of caffeic acid and ferulic acid from sorghum straws. The results showed that the oscillation-assisted hydrothermal process efficiently improved extraction of caffeic acid and ferulic acid. The oscillation-assisted hydrothermal process resulted in the extraction rates of 1275.48 and 1822.64 mg/L.h for caffeic acid and ferulic acid, respectively. Moreover, the oscillation-assisted hydrothermal process exerted destructive effects on hemicellulose, lignin and the amorphous regions of cellulose, contributing to the release of caffeic acid and ferulic acid in pretreated sorghum straws. The scavenging activities for hydroxyl, 1,1-diphenyl-2-picrylhydrazyl and 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulfonic acid radicals of the caffeic acid and ferulic acid extracts obtained by the oscillation-assisted hydrothermal process were determined to be 83.69 %, 84.17 % and 88.45 %, respectively.

Highly-efficient synthesis of biogenic selenium nanoparticles by Bacillus paramycoides and their antibacterial and antioxidant activities.

Introduction: Bacillus species are known for their ability to produce nanoparticles with various potential applications. Methods: In this study, we present a facile approach for the green synthesis of selenium nanoparticles (Se NPs) using the biogenic selenate-reducing bacterium Bacillus paramycoides 24522. We optimized the growth conditions and sodium selenite reduction efficiency (SSRE) of B. paramycoides 24522 using a response surface approach. Results: Se NPs were synthesized by reducing selenite ions with B. paramycoides 24522 at 37 °C, pH 6, and 140 r/min, resulting in stable red-colored Se NPs and maximal SSRE (99.12%). The synthesized Se NPs demonstrated lethality against Staphylococcus aureus and Escherichia coli with MICs of 400 and 600 µg/mL, and MBCs of 600 and 800 µg/mL, respectively, indicating the potential of Se NPs as antibacterial agents. Furthermore, the Se NPs showed promising antioxidant capabilities through scavenging DPPH radicals and reducing power. Discussion: This study highlights the environmentally friendly production of Se NPs using B. paramycoides 24522 and their possible applications in addressing selenium pollution, as well as in the fields of environment and biotechnology.

Properties of hydrolyzed guar gum fermented in vitro with pig fecal inocula and its favorable impacts on microbiota.

In order to identify an appropriate substitute for antibiotic use in livestock production, this study investigates the fermentation of guar gum and its low molecular weight hydrolyzed derivatives (GMLP-1, 1-10 kDa; GMLP-2, < 1 kDa) in pig fecal cultures and the associated effects on the intestinal microbiota. Both the non-hydrolyzed guar gum and GMLP were quickly utilized by fecal microbiota. GMLP-2 showed the most rapid SCFA-producing activity and produced higher concentrations of lactate, acetate, and propionate. However, GMLP-1 showed the highest yield of total SCFAs and butyrate. Both the guar gum and GMLP groups improved the abundance of Clostridium sensu stricto 1 and Bifidobacterium, but the most significant enhancement was observed with GMLP-1. This study showed that by associating with its chemical structure, GMLP-1 can be utilized to direct a targeted promotion of the intestinal microbiota and may offer the most favorable effects in livestock production.

A novel pathway for the anaerobic biotransformation of microcystin-LR using enrichment cultures.

Microcystin (MC) elimination is a global challenge that is necessary for the health of humans and ecosystems. Biodegradation of MC, one of the most environmental-friendly methods, had previously been focused on the aerobic condition. In this study, two enrichment cultures from Taihu sediments possessed high capacity for MC-leucine arginine (MC-LR) anaerobic biodegradation. Meanwhile, it was firstly found that MC-LR underwent similar degradation process under anaerobic conditions to that in aerobic condition. Furthermore, a novel degradation pathway, hydrolyzing of Ala-Mdha to form a new linear MC-LR intermediate, was proposed under anaerobic conditions. Combining MC-LR degradation with microbial community analysis, this study deduced that Candidatus Cloacamonas acidaminovorans str. Evry may play an important role in the degradation of MC-LR. These findings suggest an additional pathway involved in the environmental cycle of MC-LR, which implies that the biotransformation of MC-LR might play an important role in eliminating MC-LR in eutrophic lake sediments under anaerobic conditions.

Hydrolysis, adsorption, and biodegradation of bensulfuron methyl under methanogenic conditions.

Bensulfuron methyl (BSM), one of the most widely used herbicides in paddy soils, is frequently detected in natural and artificial aquatic systems. However, BSM transformation under methanogenic conditions has not been given sufficient attention. In this study, BSM elimination and transformation by anaerobic enrichment cultures were investigated. The results showed that BSM can be mineralized to methane through hydrolysis, adsorption, and biodegradation under a methanogenic environment. The adsorption led to protein static quenching in the extracellular polymeric substances (EPSs) of the enrichment cultures. Specifically, BSM mainly reacted with the amine, amide, amino acid, and amino sugar functional groups in proteins. BSM hydrolysis and biodegradation occurred through the breakage of the sulfonylurea bridge and sulfonyl amide linkage. The cleavage of the sulfonylurea bridge occurred in both hydrolysis and biodegradation, while the cleavage of the sulfonyl amide linkage only occurred in hydrolysis. These results elucidated the complex transformation of BSM under methanogenic conditions, which will advance the studies on sulfonylurea herbicide biotransformation and hazard assessment in the environment.

Diameter Dependence of Planar Defects in InP Nanowires.

In this work, extensive characterization and complementary theoretical analysis have been carried out on Au-catalyzed InP nanowires in order to understand the planar defect formation as a function of nanowire diameter. From the detailed transmission electron microscopic measurements, the density of stacking faults and twin defects are found to monotonically decrease as the nanowire diameter is decreased to 10 nm, and the chemical analysis clearly indicates the drastic impact of In catalytic supersaturation in Au nanoparticles on the minimized planar defect formation in miniaturized nanowires. Specifically, during the chemical vapor deposition of InP nanowires, a significant amount of planar defects is created when the catalyst seed sizes are increased with the lower degree of In supersaturation as dictated by the Gibbs-Thomson effect, and an insufficient In diffusion (or Au-rich enhancement) would lead to a reduced and non-uniform In precipitation at the NW growing interface. The results presented here provide an insight into the fabrication of "bottom-up" InP NWs with minimized defect concentration which are suitable for various device applications.