The effects of different impeller combinations in the Sphingan WL gum fermentation process.

The fermentation of the high-viscosity polysaccharide WL gum has always been associated with poor mass transfer. Appropriate impeller configurations are key factors in maintaining homogeneity and sufficient mass transfer conditions. Therefore, a flat-folded disc turbine impeller (FFDT) taking into account both the reduced cavitation effect and the increased contact area was designed. Besides, a curved cross impeller (CC) and a fishbone-shaped impeller (FS) generating axial flow were also designed. The energy consumption and efficiency of the designed impellers and eight reported impellers were evaluated through fermentation and principal component analysis (PCA). Compared to the commonly-used six-blade flat-blade disc turbine (FBDT), the ungassed power number of FFDT was reduced by 50 %. Combinations of six-blade Brumajin impeller (BM) + FFDT and CC + FFDT produced high WL gum production and viscosity (34.0 g/L, 35.50 g/L, and 62.64 Pa·s, 61.68 Pa·s, respectively) and were suitable impellers for WL biosynthesis. WL gum from BM + FFDT showed higher viscosity, viscoelasticity, and molecular weight than that from FBDT + FBDT. In addition, fewer amino acids and pyruvic acid intermediates were formed using BM + FFDT, indicating a greater metabolic flux towards WL gum synthesis. This work provided an important reference for the design of impellers in high-viscosity fermentation systems.

Cyclodextrin-Modified Amphiphilic Microgel with Bifunctional Domains for Infected Wound Healing via Photothermal Antibacterial Therapy and Nitric Oxide Release.

Bacterial infections are one of the major contributing factors to human mortality, which can cause secondary damage to the injured area, such as leading to inflammation, tissue death, and even personal death. Herein, we developed a novel cyclodextrin (CD)-modified amphiphilic microgel with a 3D network nanostructure that encapsulates hydrophilic indocyanine green (ICG) as a trigger for photothermal therapy (PTT) and hydrophobic N,N'-disubstituted-butyl-N,N'-dinitro-1,4-benzenediamine (BNN6) as a heat-sensitive nitric oxide (NO) donor (CD@I-B) to cope with bacteria-infected wound therapy. This biocompatible microgel showed excellent broad-spectrum antibacterial capability under near-infrared (NIR) laser irradiation, while the photothermal conversion process promotes the deswelling of the microgel and release of NO, which synergistically accelerates wound healing. The therapy strategy by synergizing NO delivery with PTT promoted the formation of neovascularization and collagen fiber as well as the elimination of inflammation cells, thus facilitating wound healing. Our study further demonstrates the fantastic opportunities of applying high-performance microgels to provide all-in-one sites for treating wound sterilization and healing.

Physicochemical and Structural Characterization of Alkali-Treated Biopolymer Sphingan WL Gum from Marine Sphingomonas sp. WG.

Sphingan WL gum (WL), a kind of exopolysaccharide, is produced by Sphingomonas sp. WG, which was screened from sea mud samples of Jiaozhou Bay by our group. The solubility of WL was investigated in this work. First, 1 mg/mL of WL solution was stirred at room temperature for at least 2 h to obtain a uniform opaque liquid, and further the solution became clear with the increased NaOH and stirring time. Subsequently, the structural features, solubility, and rheological properties of WL before and after alkali treatment were compared systematically. FTIR, NMR, and zeta potential results indicate that the alkali causes acetyl group hydrolysis and carboxyl group deprotonation. XRD, DLS, GPC, and AFM results suggest that the alkali destroys the ordered arrangement and inter- and intrachain entanglement of polysaccharide chains. In the same case, 0.9 M NaOH-treated WL presents better solubility (stirring for 15 min to obtain a clarified solution) but, unsurprisingly, worsens rheological properties. All results demonstrated that the good solubility and transparency of alkali-treated WL will help promote its postmodification and application.

Citric acid crosslinked sphingan WL gum hydrogel films supported ciprofloxacin for potential wound dressing application.

Sphingan WL gum (WL), a kind of exopolysaccharides, is produced by Sphingomonas sp. WG. In this study, citric acid (CA) crosslinked WL hydrogel films were firstly developed for potential wound dressing application. ATR-FTIR and TG results suggested the occurrence of esterification crosslinking. SEM analysis showed that this aided covalent crosslinking could prevent their porous structures from collapsing when swelling. Due to the deprotonation of carboxyl groups, the water absorption capacity of WL-CA hydrogel films increased with the increase of pH (maximum swelling ratio = 38 g/g). The covalent crosslinked swollen WL-CA hydrogels exhibited certain hydrolytic stability, high porosity (>60%), moderate tissue adhesion, and good rheological property (G' > G″, G' up to 2 kPa). WL-CA-CIP hydrogel films loaded with antibiotic ciprofloxacin (CIP) showed sustained drug release properties, long-lasting antibacterial activity, and superior biocompatibility. All the results indicated that WL-based hydrogels were potential candidates for wound dressing applications.

Exploring the quorum sensing inhibition of isolated chrysin from Penicillium chrysogenum DXY-1.

We recently and for the first time reported that ethyl acetate extracts isolated from Penicillium chrysogenum DXY-1 exhibited anti-quorum sensing (anti-QS) activity. Herein, another active molecule in the extracts was identified as chrysin by NMR and MS. A 20 µg/mL dose of chrysin inhibited violacein production regulated by QS in C. violaceum CV026 by 31.6%. A 40 µg/mL dose of chrysin suppressed pyocyanin production, elastase activity, proteolytic activity, and biofilm formation regulated by QS in P. aeruginosa PA01 by 41.4%, 13.8%, 8.3%, and 42.4%, respectively. And chrysin could inhibit the swarming activity of P. aeruginosa PA01. Further, molecular docking and CD analysis were used to address the mechanism of chrysin's activity in C. violaceum. Molecular docking results revealed that chrysin suppresses QS system by competing with the natural signal molecule C6HSL for binding to the same pocket of CviR receptor. At the same time, CD results also showed that chrysin could change the secondary structure composition of CviR, which greatly prevented the binding of C6HSL/CviR, and further playing its role on inhibiting bacterial QS system. All these data demonstate that chrysin may be used as a potential QS inhibitor to tackle increasing drug resistance.

A Cyclic Dipeptide from Marine Fungus Penicillium chrysogenum DXY-1 Exhibits Anti-quorum Sensing Activity.

Bacterial quorum sensing (QS) is anticipated as a new potential target for the development of antimicrobial drugs. An anti-QS substance against Chromobacterium violaceum CV026 and Pseudomonas aeruginosa PA01 has been isolated and purified from the crude extracts of the marine fungus Penicillium chrysogenum DXY-1, and the accurate structure was identified as cyclo(l-Tyr-l-Pro). This cyclic dipeptide at sub-minimum inhibitory concentration can decrease the QS-regulated violacein production of C. violaceum CV026 by 79% and QS-mediated pyocyanin production, proteases, and elastase activity of P. aeruginosa PA01 by 41%, 20%, and 32%, respectively. In addition, it can also destroy the biofilm formation and decrease QS gene expression of P. aeruginosa PA01. Molecular docking was further performed, and the obtained data indicated that this dipeptide blocks the effect of QS autoinducers through competitive binding to the same pocket of the receptor proteins. We expect this anti-QS cyclic dipeptide to be a potential pro-drug treating drug-resistant P. aeruginosa infections, and these findings could relieve the alarming problem of microbial resistance to antimicrobial drugs.

Characterization and Function of a Novel Welan Gum Lyase From Marine Sphingomonas sp. WG.

Welan gum, a kind of microbial exopolysaccharides, produced by the genus Sphingomonas, have great potential for application in many fields, such as the food industry, cement production, and enhanced oil recovery. But there are still challenges to reduce the cost, enhance the production and the quality. Herein, the bioinformatics analysis of WelR gene was preformed, and the characterization and function of WelR, welan gum lyase, from Sphingomonas sp. WG were investigated for the first time. The results indicated that 382nd (Asn), 383rd (Met), 494th (Asn), and 568th (Glu) were the key amino acid residues, and C-terminal amino acids were essential to keeping the stability of WelR. The optimal temperature and pH of the enzymatic activity were found to be 25°C and 7.4, respectively. And WelR was good low temperature resistance and alkali resistant. K+, Mg2+, Ca2+, Mn2+, and EDTA increased WelR activities, in contrast to Zn2+. Coupled with the change in glucose concentration and growth profile, the qRT-PCR results indicated that WelR may degrade welan gum existing in the culture to maintain bacterial metabolism when glucose was depleted. This work will lay a theoretical foundation to establish new strategies for the regulation of welan gum biosynthesis.

Tyrosol from marine Fungi, a novel Quorum sensing inhibitor against Chromobacterium violaceum and Pseudomonas aeruginosa.

An ethyl acetate extracts isolated from a marine fungal strain, Penicillium chrysogenum DXY-1, obtained from marine sediments surrounding the East Sea, was found to exhibit anti-quorum sensing (anti-QS) activity. Interestingly, a novel active compound was identified as tyrosol by the purification and structural characterization. At a concentration of 0.5 mg/mL, tyrosol decreased QS-regulated violacein production in Chromobacterium violaceum CV026 by 53.5% and decreased QS-regulated pyocyanin production, elastase activity and proteolytic activity in Pseudomonas aeruginosa PA01 by 63.3%, 57.8% and 9.9%, respectively. SEM images showed that tyrosol inhibited biofilm formation in P. aeruginosa PA01 without having any effect on bacterial growth. Molecular docking results revealed that the natural signal molecule C6HSL and tyrosol bound to different receptor pockets of CviR, and tyrosol inhibited the QS activity of CviR in C. violaceum by binding to the DNA-binding domain and blocking pathogenic gene expression. All the data suggest that tyrosol may act as a potential inhibitor of the QS systems to solve the looming crisis of bacterial resistance. We believe that there are other active compounds with relatively high anti-QS activity or synergistic inhibitory effects on QS in the crude extract, which warrants further research.

Characterization of the biosynthetic pathway of nucleotide sugar precursor UDP-glucose during sphingan WL gum production in Sphingomonas sp. WG.

To elucidate the possible biosynthetic pathway of a precursor UDP-glucose of the sphingan WL gum produced by Sphingomonas sp. WG, two enzymes phosphoglucomutase (PGM) and UDP-glucose pyrophosphorylase (UGPase) were bioinformatically analysed, expressed in Escherichia coli BL21 (DE3) and characterized. PGM was in the phosphoglucomutase/phosphomannomutase subclass and UGPase was predicted to be a UDP-glucose pyrophosphatase in a tetrameric structure. Both enzymes were expressed in soluble form, purified to near homogeneity with high activity at 1159 and 796 U/mg, exhibited folding with reasonable secondary structures, and existed as monomer and tetramer, respectively. The optimal pH and temperature of PGM were 9.0 and 50 °C, respectively, and this protein was stable at pH 8.0 and at temperatures ranging from 40 to 50 °C. The optimal pH and temperature of UGPase were 9.0 and 45 °C, respectively, and the protein was stable at pH 8.0 and at temperatures ranging from 30 to 55 °C. A small-scale one-pot biosynthesis of UDP-glucose by combining PGM and UGPase using glucose-6-phosphate and UTP as substrates was also performed, and formation of UDP-glucose was observed by HPLC detection, which confirmed the biosynthetic pathway of UDP-glucose in vitro. PGM and UGPase will be ideal targets for the metabolic engineering to improve WL gum yields in industrial production.

Significantly improved production of Welan gum by Sphingomonas sp. WG through a novel quorum-sensing-interfering dipeptide cyclo(L-Pro-L-Phe).

A variety of physiological functions such as exopolysaccharide synthesis, antibiotic production, and primary metabolism are tightly controlled by quorum sensing in microorganisms. In this study, a marine-derived bacterium Sphingomonas sp. WG was found to possess a cyclo(L-Pro-L-Phe)-mediated quorum sensing mechanism. The cyclo(L-Pro-L-Phe) produced by Sphingomonas sp. WG functions as a signalling molecule in this quorum sensing system. It is the first attempt to characterize cyclic dipeptides as quorum sensing signalling molecules in Sphingomonas sp. and the results effectively make the classical quorum sensing theory more perfect. Furthermore, the supplementation with isolated cyclo(L-Pro-L-Phe) resulted in a 15% increase in the production of welan gum secreted by Sphingomonas sp. WG in the submerged fermentation. The data presented in this study will provide evidences for exploring the role of cyclic dipeptides in regulating the production of welan gum.

Immobilization of sulfur in microgels for lithium-sulfur battery.

Immobilization of sulfur in microgels is achieved via free radical polymerization of commercial poly(ethylene glycol) dimethacrylate in the solution of sulfur-terminated poly(3-oligo(ethylene oxide)4-thiophene), a copolymer prepared by the inverse vulcanization of S8 with allyl-terminated poly(3-oligo(ethylene oxide)4-thiophene). This microgelation leads to enhanced Li-S battery performance over the sulfur-terminated polymer.

Glucose-mediated catalysis of Au nanoparticles in microgels.

The catalytic activity of Au nanoparticles in phenylboronic acid-containing polymer microgels can be tuned through the swelling-deswelling transition of the microgels in response to changes in glucose concentration. Upon adding glucose, the model catalytic reduction of hydrophilic 4-nitrophenol is accelerated, while the reduction of relatively more hydrophobic nitrobenzene slows down.

Enhanced enzymatic hydrolysis of cellulose in microgels.

A cellulose-based microgel, where an individual microgel contains approximately one cellulose chain on average, is synthesized via free radical polymerization of a difunctional small-molecule N,N'-methylenebisacrylamide in cellulose solution. This microgelation leads to a low-ordered cellulose, favoring enzymatic hydrolysis of cellulose to generate glucose.

Copper on responsive polymer microgels: a recyclable catalyst exhibiting tunable catalytic activity.

Copper has been immobilized on a chitosan-based responsive polymer microgel by simply stirring the microgel dispersion with copper sulfate. The ensuing catalyst is highly active for a model azide-alkyne [3+2]-cycloaddition reaction, and can be recycled at least 5 times; the catalytic activity can be tuned via swelling-deswelling transitions of the polymer gels.

One-pot aqueous synthesis of sub-10 nm responsive nanogels.

A strategy involving free radical copolymerization of a difunctional oligomer and a small-molecule crosslinker to give sub-10 nm nanogels is proposed. These nanogels can adapt to surrounding temperatures and regulate the release of a preloaded model anticancer drug 5-fluorouracil.

Taiwanese version of the M. D. Anderson symptom inventory: symptom assessment in cancer patients.

The purpose of this study was to validate the Taiwanese version of the M. D. Anderson Symptom Inventory (MDASI-T) in a sample of 556 Taiwanese patients with multiple diagnoses of cancer. The internal consistency Cronbach alpha was 0.89 for symptom severity items and 0.94 for interference items. The test-retest reliability was 0.97 for the severity composite score and 0.96 for the interference composite score over a 3-day interval in a sample of 12 patients. Construct validity was established by factor analysis, which revealed a two-factor structure. Concurrent validity was examined by correlating the MADSI-T scores and scores of the Medical Outcome Study 36-Item Short-Form Health Survey. Known-group validity was established by comparing MDASI-T scores between patients having low functional status and those having high functional status (Karnofsky Performance Status scores50, respectively) and between inpatients and outpatients. The MDASI-T's sensitivity (its ability to detect small differences in reporting variations) was examined by comparing the MDASI-T composite symptom scores and composite interference scores before, during, and one week after treatment in a sample of 20 breast cancer patients receiving chemotherapy. The MDASI-T is a reliable, valid, and sensitive instrument for measuring the severity and interference with daily life of cancer-related symptoms among Taiwanese cancer patients.

Validation of the Taiwanese version of the Brief Fatigue Inventory.

We validated the Taiwanese version of the Brief Fatigue Inventory (BFI-T) in a sample of 439 Taiwanese patients with multiple cancer diagnoses. Internal consistency was indicated by Cronbach alphas of 0.96 for fatigue-related severity and 0.95 for interference. Test-retest reliability was 0.89 for fatigue severity and 0.91 for interference. Factor analysis revealed a one-factor structure. Convergent validity was examined by correlating the BFI-T worst fatigue and fatigue severity composite scores with POMS vigor and fatigue subscales scores. Known-group validity was established by comparing BFI-T worst fatigue and severity composite scores between patients with low functional status and high functional status and between inpatients and outpatients. The BFI-T's sensitivity was examined by comparing BFI-T severity and interference composite scores before, during, and after chemotherapy treatment in a subsample of 20 breast cancer patients. The BFI-T is reliable, valid, and sensitive for measuring cancer-related fatigue severity and interference among Taiwanese cancer patients.