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Based on our previous findings that salicylic acid and jasmonic acid increased Nostoc flagelliforme polysaccharide yield by regulating intracellular nitric oxide (NO) levels, the mechanism through which NO affects polysaccharide biosynthesis in Nostoc flagelliforme was explored from the perspective of S-nitrosylation (SNO). The addition of NO donor and scavenger showed that intracellular NO had a significant positive effect on the polysaccharide yield of N. flagelliforme. To explore the mechanism, we investigated the relationship between NO levels and the activity of several key enzymes involved in polysaccharide biosynthesis, including fructose 1,6-bisphosphate aldolase (FBA), glucokinase (GK), glucose 6-phosphate dehydrogenase (G6PDH), mitochondrial isocitrate dehydrogenase (ICDH), and UDP-glucose dehydrogenase (UGDH). The enzymatic activities of G6PDH, ICDH, and UGDH were shown to be significantly correlated with the shifts in intracellular NO levels. For further validation, G6PDH, ICDH, and UGDH were heterologously expressed in Escherichia coli and purified via Ni + -NAT affinity chromatography, and subjected to a biotin switch assay and western blot analysis, which revealed that UGDH and G6PDH were susceptible to SNO. Furthermore, mass spectrometry analysis of proteins treated with S-nitrosoglutathione (GSNO) identified the SNO modification sites for UGDH and G6PDH as cysteine 423 and cysteine 249, respectively. These findings suggest that NO modulates polysaccharide biosynthesis in N. flagelliforme through SNO of UGDH and G6PDH. This reveals a potential mechanism through which NO promotes polysaccharide synthesis in N. flagelliforme, while also providing a new strategy for improving the industrial production of polysaccharides., (© 2024. The Author(s).)

Retinol is one of the main active forms of vitamin A, crucial for the organism's growth, development, and maintenance of eye and skin functions. It is widely used in cosmetics, pharmaceuticals, and feed additives. Although animals lack a complete pathway for synthesizing vitamin A internally, they can obtain vitamin A directly through diet or convert β-carotene acquired from the diet. To boost the research on the biosynthesis of retinol, three different sources of alcohol dehydrogenase were firstly screened based on the β-carotene synthesis platform CAR*1. It was determined that ybbO from Escherichia coli exhibited the highest catalytic activity,with a conversion rate of 95. 6%. To further enhance the reaction rate and yield of retinol, protein fusion technology was employed to merge two adjacent enzymes, blh and ybbO, within the retinol synthesis module. The evaluation was conducted using the high-yield engineered strain CAR*3 of β-carotene. The optimal combination, blh-GGGS-ybbO, was obtained, with a 44. 9% increase in yield after fusion, reaching(111. 1± 3. 5) mg·L~(-1). Furthermore, through the introduction of human-derived retinol-binding protein(RBP4) and transthyretin(TTR), the process of hepatic cell secreting retinol was simulated in Saccharomyces cerevisiae, leading to an increased retinol yield of(158. 0±13. 1)mg·L~(-1). Finally, optimization strategies including overexpressing INO2 to enhance the reaction area for β-carotene synthesis, enhancing hemoglobin VHb expression to improve oxygen supply, and strengthening PDR3m expression to facilitate retinol transport were implemented. A two-stage fermentation process resulted in the successful elevation of retinol production to(2 320. 0±26. 0)mg·L~(-1) in the fermentation tank of 5 L, which provided a significant foundation for the industrial development of retinol.

Statement of Problem: Factors influencing early implant failure (failure during the healing period) in the rehabilitation and restoration of oral function in partially edentulous patients are unclear., Purpose: The purpose of this clinical study was to investigate several factors that may be associated with early implant failure., Material and Methods: This retrospective study was conducted on 3247 implants in 2061 patients between 2009 and 2022. Patient-related and surgery-related factors, including smoking; sex; diabetes; bone grafting; implant length, diameter, and design; adjacent teeth; and insertion torque, were manually retrieved and analyzed. Using univariate and multivariate analyses, a generalized estimating equation (GEE) model with chi-squared tests was employed to evaluate factors related to early implant failure (the failure before restoration) (α=.05)., Results: The mean ±standard deviation age of the study patients was 49.2 ±15.0 years (range 18 to 91). Ninety-nine implants (3.05%) failed during the healing period. Three factors were statistically significant regarding early implant failure: smoking (odds ratio [OR]=1.92, P=.008), implant design (tapered implants) (OR=1.84, P=.007), and implant length <10 mm (OR=2.98, P=.011). Factors including diabetes, bone grafting, anatomic location, adjacent teeth (endodontic therapy in the adjacent teeth and the distance between implant and adjacent teeth), healing method, and insertion torque did not exhibit a statistically significant higher early implant failure rate. Ninety-three sites with failed implants received new implants, and 6 of these 93 implants failed during the healing period., Conclusions: Within the limitation of sample size, smokers, implant length (<10 mm), and implant design (tapered implant) exhibited higher risk of early implant failure in this retrospective study. Implant insertion torque, healing method, adjacent teeth, and diabetes did not significantly influence the risk of early implant failure., (Copyright © 2024 Editorial Council for The Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Grifola frodosa polysaccharides, especially β-D-glucans, possess significant anti-tumor, antioxidant and immunostimulatory activities. However, the synthesis mechanism remains to be elucidated. A newly discovered glycosyltransferase UGT88A1 was found to extend glucan chains in vitro. However, the role of UGT88A1 in the growth and polysaccharide synthesis of G. frondosa in vivo remains unclear. In this study, the overexpression of UGT88A1 improved mycelial growth, increased polysaccharide production, and decreased cell wall pressure sensitivity. Biomass and polysaccharide production decreased in the silenced strain, and the pressure sensitivity of the cell wall increased. Overexpression and silencing of UGT88A1 both affected the monosaccharide composition and surface morphology of G. frondosa polysaccharides and influenced the antioxidant activity of polysaccharides from different strains. The messenger RNA expression of glucan synthase (GLS), UTP-glucose-1-phosphate uridylyltransferase (UGP), and UDP-xylose-4-epimerase (UXE) related to polysaccharide synthesis, and genes related to cell wall integrity increased in the overexpression strain. Overall, our study indicates that UGT88A1 plays an important role in the growth, stress, and polysaccharide synthesis of G. frondosa, providing a reference for exploring the pathway of polysaccharide synthesis and metabolic regulation. KEY POINTS: •UGT88A1 plays an important role in the growth, stress response, and polysaccharide synthesis in G. frondosa. •UGT88A1 affected the monosaccharide composition, surface morphology and antioxidant activity of G. frondosa polysaccharides. •UGT88A1 regulated the mRNA expression of genes related to polysaccharide synthesis and cell wall integrity., (© 2024. The Author(s).)

The outbreak of novel coronavirus disease 2019 (COVID-19), caused by the novel coronavirus (SARS-CoV-2), has had a significant impact on human health and the economic development. SARS-CoV-2 3CL protease (3CLpro) is highly conserved and plays a key role in mediating the transcription of virus replication. It is an ideal target for the design and screening of anti-coronavirus drugs. In this work, seven β-nitrostyrene derivatives were synthesized by Henry reaction and β-dehydration reaction, and their inhibitory effects on SARS-CoV-2 3CL protease were identified by enzyme activity inhibition assay in vitro. Among them, 4-nitro-β-nitrostyrene (compound a ) showed the lowest IC 50 values of 0.7297 µM. To investigate the key groups that determine the activity of β-nitrostyrene derivatives and their interaction mode with the receptor, the molecular docking using the CDOCKER protocol in Discovery Studio 2016 was performed. The results showed that the hydrogen bonds between β-NO 2 and receptor GLY-143 and the π-π stacking between the aryl ring of the ligand and the imidazole ring of receptor HIS-41 significantly contributed to the ligand activity. Furthermore, the ligand-receptor absolute binding Gibbs free energies were calculated using the Binding Affinity Tool (BAT.py) to verify its correlation with the activity of β-nitrostyrene 3CLpro inhibitors as a scoring function. The higher correlation(r 2 =0.6) indicates that the absolute binding Gibbs free energy based on molecular dynamics can be used to predict the activity of new β-nitrostyrene 3CLpro inhibitors. These results provide valuable insights for the functional group-based design, structure optimization and the discovery of high accuracy activity prediction means of anti-COVID-19 lead compounds., Competing Interests: All co-authors declare that there are no conflicts of interest., (© 2023 Published by Elsevier B.V.)

To significantly improve the polysaccharide production of Nostoc flagelliforme , a total of 12 chemicals were evaluated for their effects on polysaccharide accumulation. The results showed that salicylic acid and jasmonic acid increased the accumulation of the polysaccharides in N. flagelliforme significantly, by more than 20%. Three polysaccharides, namely control-capsule polysaccharide, salicylic acid-capsule polysaccharide, and jasmonic acid-capsule polysaccharide, were extracted and purified from N. flagelliforme under normal, salicylic acid, and jasmonic acid culture conditions, respectively. Their chemical compositions slightly differed regarding the total sugar and uronic acid contents, with average molecular weights of 2.06 × 10 3 , 2.16 × 10 3 and 2.04 × 10 3 kDa, respectively. They presented similar Fourier transform infrared spectra and no significant difference in antioxidant activity. It was revealed that the salicylic acid and jasmonic acid significantly increased the level of nitric oxide. By investigating the effects of the exogenous nitric oxide scavenger and nitric oxide donor on the nitric oxide levels and polysaccharide yield of N. flagelliforme , the results showed that the increase in intracellular nitric oxide levels might be an important factor promoting the accumulation of polysaccharides. These findings provide a theoretical foundation for enhancing the yield of secondary metabolites by regulating the intracellular nitric oxide levels.

Four polysaccharide fractions were isolated and purified from the culture supernatant and mycelium of Poria cocos, and differences in their immunomodulatory activity were investigated. The average molecular weights of EPS-0M, EPS-0.1M, IPS-0M, and IPS-0.1M were 1.77 × 10 3 , 2.01 × 10 3 , 0.03 × 10 3 and 4.97 × 10 3  kDa, respectively. They all mainly consisted of 5 monosaccharides, including glucose, mannose, galactose, fucose and rhamnose, but with different molar ratios. At a dose of 50 μg/mL, EPS-0M, EPS-0.1M, and IPS-0.1M significantly increased the production of nitric oxide (NO), as well as the mRNA and protein levels of pro-inflammatory factors including interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) in RAW264.7 cells, suggesting that they enhanced macrophage-mediated innate immunity. Moreover, based on the in vitro inflammation model of lipopolysaccharide (LPS)-stimulated RAW264.7 cells, EPS-0M, EPS-0.1M and IPS-0M but not IPS-0.1M could inhibit the LPS-induced excessive inflammatory response, including NO, IL-6, TNF-α, IL-1β production and gene transcription. Interestingly, IPS-0M showed a relatively poor immunostimulatory effect, but had the strongest inhibitory effect against the LPS-induced RAW264.7 inflammatory response. Furthermore, our results indicate that the nuclear factor-kappa B (NF-κB) pathway is associated with the immunomodulatory effects of the polysaccharide samples on RAW264.7 cells. This study can provide a reference for the more targeted application of different polysaccharide components from Poria cocos for human health., Competing Interests: Conflict of interest There are no conflicts to declare., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Komagataeibacter xylinus is an aerobic strain that produces bacterial cellulose (BC). Oxygen levels play a critical role in regulating BC synthesis in K. xylinus, and an increase in oxygen tension generally means a decrease in BC production. Fumarate nitrate reduction protein (FNR) and aerobic respiration control protein A (ArcA) are hypoxia-inducible factors, which can signal whether oxygen is present in the environment. In this study, FNR and ArcA were used to enhance the efficiency of oxygen signaling in K. xylinus, and globally regulate the transcription of the genome to cope with hypoxic conditions, with the goal of improving growth and BC production. FNR and ArcA were individually overexpressed in K. xylinus, and the engineered strains were cultivated under different oxygen tensions to explore how their overexpression affects cellular metabolism and regulation. Although FNR overexpression did not improve BC production, ArcA overexpression increased BC production by 24.0% and 37.5% as compared to the control under oxygen tensions of 15% and 40%, respectively. Transcriptome analysis showed that FNR and ArcA overexpression changed the way K. xylinus coped with oxygen tension changes, and that both FNR and ArcA overexpression enhanced the BC synthesis pathway. The results of this study provide a new perspective on the effect of oxygen signaling on growth and BC production in K. xylinus and suggest a promising strategy for enhancing BC production through metabolic engineering. KEY POINTS: • K. xylinus BC production increased after overexpression of ArcA • The young's modulus is enhanced by the ArcA overexpression • ArcA and FNR overexpression changed how cells coped with changes in oxygen tension., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The nanostructured antimicrobial agents, self-assembled by the antimicrobial peptides (AMPs), represent an intriguing platform for the treatment of pathogens. Although the structural characteristics significantly influence antimicrobial functionality, the role of chirality is usually ignored and still unclear. Herein, two homochiral AMPs (all L- or all D-amino acids), including C 16 - L V 4 L R 4 (LL) and C 16 - D V 4 D R 4 (DD), and a heterochiral AMP with alternating D-/L-amino acids, C 16 - D V 4 L R 4 (DL), were self-assembled into left-handed, right-handed, and right-handed helical nanofibers, respectively. The valine configuration determined the supramolecular chirality of the nanofibers. However, the DL molecules exhibited a highly aggregated propensity to form more stable helical nanofibers with a lower degree of twist and a larger helical pitch. This characteristic resulted in the optimal antimicrobial activity of the DL nanofibers against both Gram-negative and Gram-positive bacteria. Furthermore, the membrane permeability assay confirmed the higher activity for damaging the cell membrane by the DL nanofibers. These results demonstrated the significance of molecular chirality in directing the self-assembly of the amphiphilic peptides, eventually affecting their antimicrobial activity. This study opens up the possibility to fabricate promising nanostructured antimicrobial materials by controlling the chirality and structure of the materials., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier Inc.)

Superhydrophilic/underwater superoleophobic (SUS) membrane technology has attracted extensive attention for water purification. However, the fabrication of multifunctional membranes to satisfy the complex wastewater treatment is still a big challenge. In this work, bacterial cellulose (BC) based multifunctional SUS membranes were designed for water purification. Membranes were prepared by blending BC nanofibers with TiO 2 nanoparticles (NPs), and further modified by the in situ growth of ZnO-NPs. The composite membranes showed oil/water (o/w) separation under a small driving pressure (0.2-0.3 bar) with a flux rate of 8232.81 ± 212 L m - 2 h -1 and with a high separation efficiency (>99.9%). Membranes could also separate oil-in-water emulsion with a separation flux of 1498 ± 74 L m - 2 h -1 and with high efficiency (99.25%). Moreover, the composite membrane exhibited photocatalytic activity under visible light with a high efficiency (>92%). The composite membranes were also investigated for antibacterial activity against Gram-positive and Gram-negative bacterial strains. This work may inspire the fabrication of next-generation multifunctional membranes for wastewater treatment, particularly oily wastewater, dyes and microbial contaminated water., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Two capsular polysaccharides (WL-CPS-1 and GLU-CPS-1) purified from Nostoc flagelliforme under normal and mixotrophic culture conditions were used to investigate the hypolipidemic activity and effect on intestinal flora in C57BL/6J mice respectively. Their molecular weight and monosaccharide composition have been determined in previous studies. They both improved the lipid level by affecting the expression of lipid metabolism genes. They down-regulated the TNF-α and IL-1β levels in serum and up-regulated the activity of antioxidant enzymes in liver thus decreased the atherosclerosis index and MDA content. They up-regulated the short chain fatty acids (SCFAs) synthesis. They decreased the abundance of pathogenic bacteria and increased the abundance of probiotics positively correlated with SCFAs. Compared with WL-CPS-1, GLU-CPS-1 exhibited higher in vivo activity and enriched Odoribacter and Alloprevotella correlating with the gene expression of lipid metabolism, suggesting that the bioactivity of polysaccharides could be regulated by culture conditions. These findings contributed to application of N. flagelliforme polysaccharides with higher activity in hypolipidemia by adjusting culture conditions., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Bacterial cellulose (BC) is a promising biopolymer, but its three-dimensional structure needs to be controllable to be used in multiple fields. BC has some advantages over other types of cellulose, not only in terms of purity and properties but also in terms of modification (in situ modification) during the synthesis process. Here, starches from different sources or with amylose/amylopectin content were added to the growth medium to regulate the structural properties of BC in-situ. The obtained BC membranes were further modified by superhydrophobic treatment for oil-water separation. Starches alter the viscosity of the medium, thus affecting bacterial motility and cellulose synthesis, and adhere to the microfibers, limiting their further polymerization and ultimately altering the membrane porosity, pore size, and mechanical properties perpendicular to the BC fibril layer direction. The average pore diameter of the BC/PS membrane increased by 1.94 times compared to the initial BC membrane. The chemically modified BC/PS membrane exhibited super-hydrophobicity (water contact angle 167°), high oil-water separation flux (dichloromethane, 23,205 Lm -2  h -1  MPa -1 ), high separation efficiency (>97%). The study provides a foundation for developing methods to regulate the network structure of BC and broaden its application., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Bacterial cellulose (BC) is an important polysaccharide synthesized by some bacterial species under specific culture conditions, which presents several remarkable features such as microporosity, high water holding capacity, good mechanical properties and good biocompatibility, making it a potential biomaterial for medical applications. Since its discovery, BC has been used for wound dressing, drug delivery, artificial blood vessels, bone tissue engineering, and so forth. Additionally, BC can be simply manipulated to form its derivatives or composites with enhanced physicochemical and functional properties. Several polymers, carbon-based nanomaterials, and metal nanoparticles (NPs) have been introduced into BC by ex situ and in situ methods to design hybrid materials with enhanced functional properties. This review provides comprehensive knowledge and highlights recent advances in BC production strategies, its structural features, various in situ and ex situ modification techniques, and its potential for biomedical applications., (Copyright © 2021 Elsevier Inc. All rights reserved.)

A strategy by exogenous addition of quorum sensing molecule farnesol to improve the production, antioxidant activity and antitumor activity of extracellular polysaccharide (EPS) of Grifola frondosa by liquid fermentation was proposed in the study. The highest yield of EPS induced by farnesol was 1.25 g/L, which was 150% higher than that of the control. Four polysaccharides including EPS-C-0M, EPS-C-0.2M, EPS-F-0M and EPS-F-0.2M were extracted and purified under the conditions of control and farnesol respectively. The physicochemical properties, antioxidant activities and antitumor activities were studied. Their chemical composition differed in sugar, protein and uronic acid contents, and they were composed of six constituent monosaccharides with different ratios, with the average molecular weights of 1.12 × 10 3 , 1.89 × 10 3 , 1.41 × 10 3 and 2.02 × 10 3 kDa, respectively. They presented similar FT-IR spectra, but different surface morphology. Antioxidant experiments showed that they had strong scavenging activities on ABTS + , hydroxyl radical, O 2- and DPPH radical. Antitumor experiments showed that they had strong inhibitory effects on human cervical cancer (HeLa) cells and human liver cancer cells (HepG 2 ) cells. Among the four polysaccharides, EPS-F-0.2M showed the highest antioxidant and antitumor activities, indicating that farnesol could regulate the biological activity of EPS by affecting structure and properties. These results demonstrated that appropriate adjustment of culture conditions had potential application in the development of polysaccharides with high antioxidant and antitumor activity. It provided a new strategy to enhance the production and bioactivity of edible and medicinal fungal polysaccharides by using quorum sensing molecules., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Hydrogels with pH sensitivity and stable mechanical and antibacterial properties have many desirable qualities and broad applications. A hydrogel based on bacterial cellulose and chitosan, impregnated with silver sulfadiazine (<1% w/w), was prepared using glutaraldehyde as the crosslinking agent. The presence of SSd was confirmed by Fourier transform infrared spectroscopy. Micropore size, swelling ratio, pH- sensitivity, and gram positive and negative antibacterial properties were studied by disk diffusion and colony forming unit. X-ray diffraction confirmed the presence of amorphous and crystalline regions in the hydrogel matrix following addition of SSd. The elemental composition, morphology, and mechanical properties of the hydrogels were characterized. Incorporation of SSd into bacterial cellulose-chitosan hydrogels significantly improved their mechanical and antibacterial properties. The antibacterial activity against E. coli and S. aureus was evaluated and SSd-BC/Ch hydrogels are more toxic to S. aureus than to E. coli. We use FESEM to observe bacterial morphology before and after exposure to SSd-BC/Ch hydrogels. The BacLight LIVE/DEAD membrane permeability kit is used to evaluate the membrane permeability of bacteria. These antibacterial hydrogels have many promising applications in food packaging, tissue engineering, drug delivery, clinical, biotechnological, and biomedical fields., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Quorum sensing is a mechanism that facilitates cell-to-cell communication. Through signal molecular density for signal recognition, which leads to the regulation of some physiological and biochemical functions. Gluconacetobacter xylinus CGMCC 2955, which produces bacterial cellulose (BC), synthesizes the LuxR protein belonging to the LuxI/LuxR type QS system. Here, a luxR overexpression vector was transformed into G. xylinus CGMCC 2955. The overexpression of luxR increased the yield of BC by 15.6% after 16 days static culture and reduced the cell density by 15.5% after 120-h-agitated culture. The glucose was used up by G. xylinus-pMV24-luxR at 72-h-agitated fermentation, which 12 h earlier than the wild-type (WT). The total N-acylhomoserine lactones (AHL) content of the luxR-overexpressing strain and the WT strain attained 1367.9 ± 57.86 mg/L and 842.9 ± 54.22 mg/L, respectively. The C 12 -HSL and C 14 -HSL contents of G. xylinus-pMV24-luxR were 202 ± 21.66 mg/L and 409.6 ± 0.91 mg/L, which were significantly lower than that of WT. In contrast, C 6 -HSL showed opposite results. The difference of AHL content proved that overexpression of luxR improved the binding of AHL and showed preference for some specific AHL. The metabolic results demonstrated that upon glucose exhaustion, the consumption of gluconic acid was promoted by luxR overexpression, and the content of D- ( +)-trehalose, an antiretrograde metabolite, increased significantly. KEY POINTS: • The overexpression of luxR increased the yield of bacterial cellulose • The content of signal molecules was significantly different • Differential metabolites were involved in multiple metabolic pathways., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Microbially induced calcium carbonate precipitation (MICP) has recently become an intelligent and environmentally friendly method for repairing cracks in concrete. To improve on this ability of microbial materials concrete repair, we applied random mutagenesis and optimization of mineralization conditions to improve the quantity and crystal form of microbially precipitated calcium carbonate. Sporosarcina pasteurii ATCC 11859 was used as the starting strain to obtain the mutant with high urease activity by atmospheric and room temperature plasma (ARTP) mutagenesis. Next, we investigated the optimal biomineralization conditions and precipitation crystal form using Plackett-Burman experimental design and response surface methodology (RSM). Biomineralization with 0.73 mol/l calcium chloride, 45 g/l urea, reaction temperature of 45°C, and reaction time of 22 h, significantly increased the amount of precipitated calcium carbonate, which was deposited in the form of calcite crystals. Finally, the repair of concrete using the optimized biomineralization process was evaluated. A comparison of water absorption and adhesion of concrete specimens before and after repairs showed that concrete cracks and surface defects could be efficiently repaired. This study provides a new method to engineer biocementing material for concrete repair.

Objective: To analyze the differences in clinical and biochemical characteristics and treatment effects in patients with different genotypes of Prader-Willi syndrome (PWS). Methods: A total of 35 patients with PWS, 20 males and 15 females aged from 0.8 to 10.0 years with an average age of 3.0 years, were retrospectively included in this study. All of them were treated in the Department of Endocrinology of Peking Union Medical College Hospital from May 2017 to December 2018. The clinical material, biochemical data, and peripheral blood samples of the patients were collected. Genomic DNA was extracted from peripheral blood leukocytes of patients, and methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) was used to detect gene deletion or abnormal methylation. According to the results of detection, 35 patients were divided into two groups: paternal deletion group( n =27) and methylation abnormal group( n =8). The biochemical test results and the effect of growth hormone (GH) treatment of the two groups were analyzed. Results: MS-MLPA showed that 77% (27/35) of the patients were confirmed paternal deletion and 23% (8/35) were abnormal methylation. In terms of biochemical test results, the plasma concentrations of uric acid(UA) in the paternal deletion group were higher than that in the abnormal methylation group [(363±101) μmol/L vs (259±74) μ mol/L, P =0.019 ]. There is a linear relationship between body weight and uric acid level. After adjustment for weight., there was no significant difference in UA level between the two groups ( P =0.101). Patients in both groups were treated with GH ((0.14±0.03) U/kg, QD). In paternal deletion group, patients were followed up for (26.0±13.6) months, and their height increased from (99.0±31.5) cm [(-0.3±1.1) SDS] to (107.5±27.0) cm [(0.7±0.9) SDS] ( P =0.037). In the abnormal methylation group, patients were followed up for (25.8±11.6) months, and their height increased from (86.4±31.2) cm [(-0.7±1.8) SDS] to (95.6±26.5) cm [(0.0±1.6) SDS] ( P =0.557). There was no significant difference in body mass index (BMI) between paternal deletion group and abnormal methylation group before and after treatment [(22.0±7.1) vs (22.4±6.8)] kg/m 2 , P =0.890;(17.0±3.1) vs (16.4±2.7) kg/m 2 , P =0.754]. Conclusions: There were no significant differences in biochemical test results between patients with paternal deletion and those with abnormal methylation. Early treatment with GH in PWS patients can effectively improve the increasing height and reduce excessive weight gain.

Bacterial cellulose (BC) holds several unique properties such as high water retention capability, flexibility, biocompatibility, and high absorption capacity. All these features make it a potential material for wound healing applications. However, it lacks antibacterial properties, which hampers its applications for infectious wound healings. This study reported BC-based dressings containing ε-polylysine (ε-PL), cross-linked by a biocompatible and mussel-inspired polydopamine (PDA) for promoting infectious wound healing. BC membranes were coated with PDA by a simple self-polymerization process, followed by treating with different contents of ε-PL. The resulted membranes showed strong antibacterial properties against tested bacteria by both in vitro and in vivo evaluations. The membranes also exhibited hemocompatibility and cytocompatibility by in vitro investigations. Moreover, the functionalized membranes promoted infected wound healing using Sprague-Dawley rats as a model animal. A complete wound healing was observed in the group treated with functionalized membranes, while wounds were still open for control and pure BC groups in the same duration. Histological investigations indicated that the thickness of newborn skin was greater and smoother in the groups treated with modified membranes in comparison to neat BC or control groups. These results revealed that the functionalized membranes have great potential as a dressing material for infected wounds in future clinical applications.

The oil/water (o/w) separation is a global challenge because of the increasing water contamination by oil spill accidents, and oil-containing wastewater produced by food, textile, and petrochemical industries. In this study, we have developed bacterial cellulose (BC) based superhydrophilic/underwater superoleophobic (SUS) membrane for o/w separation. The membrane was designed through a facile method by blending BC nanofibers with silica microparticles (SiO 2 -MPs), which was further modified by bio-inspired polydopamine (PDA) coatings. The composite membrane exhibited SiO 2 -MPs dependent o/w separation with a high separation efficiency of >99.9 % and a high flux rate of ∼10,660 Lm -2  h -1 while applying a small negative pressure (0.3-0.5 bar). The membrane with different content of SiO 2 -MPs also showed the potential to separate oil-in-water emulsion with the highest oil rejection of 98.2 % and the highest flux rate of ∼1250 Lm -2  h -1 on an ultra-low pressure <0.1 bar. Moreover, the membrane showed antifouling properties, recyclability, and stability in harsh conditions., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Bacterial cellulose (BC) is a substrate material with high purity and robust mechanical strength, but due to its small pore size and relatively expensive price, it is restricted as an oil-/water separation membrane. In this study, cheaper plant cellulose needle-leaf bleached kraft pulp (NBKP) was added to BC to increase the pore size of the composite membrane, and a superhydrophobic/superoleophilic membrane was prepared for oil-/water separation. The modified membrane surface displayed a petal-like micro-structure and a water contact angle (WCA) of 162.3°, while the oil contact angle was decreased to 0°. What's more, the membrane exhibited excellent oil-/water separation under gravity, recyclability, and a separation efficiency (>95 %), and it was both pH and salt resistant. The membrane also remained durably hydrophobic after 10 separation cycles. And the separation methodology is expected to be highly energy-efficient., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Surface oxidation of bacterial cellulose (BC) was done with the TEMPO-mediated oxidation mechanism system. After that, TEMPO-oxidized bacterial cellulose (TOBC) was impregnated with silver sulfadiazine (AgSD) to prepare nanocomposite membranes. Fourier transform infrared spectroscopy (FTIR) was carried out to determine the existence of aldehyde groups on BC nanofibers and X-ray diffraction (XRD) demonstrated the degree of crystallinity. FESEM analysis revealed the impregnation of AgSD nanoparticles at TOBC nanocomposites with the average diameter size ranging from 11 nm to 17.5 nm. The sample OBCS 3 showed higher antibacterial activity against Staphylococcus aureus, Pseudomonas aeruginosa , and Escherichia coli by the disc diffusion method. The results showed AgSD content, dependent antibacterial activity against all tested bacteria, and degree of crystallinity increases with TOBC and AgSD. The main advantage of the applications of TEMPO-mediated oxidation to BC nanofibers is that the crystallinity of BC nanofibers is unchanged and increased after the oxidation. Also enhanced the reactivity of BC as it is one of the most promising method for cellulose fabrication and functionalization. We believe that the novel composite membrane could be a potential candidate for biomedical applications like wound dressing, BC scaffold, and tissue engineering., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Khattak, Qin, Wahid, Huang, Xie, Jia and Zhong.)

Komagataeibacter xylinus has received increasing attention as an important microorganism for the conversion of several carbon sources to bacterial cellulose (BC). However, BC productivity has been impeded by the lack of efficient genetic engineering techniques. In this study, a lambda Red and FLP/FRT-mediated site-specific recombination system was successfully established in Komagataeibacter xylinus . Using this system, the membrane bound gene gcd , a gene that encodes glucose dehydrogenase, was knocked out to reduce the modification of glucose to gluconic acid. The engineered strain could not produce any gluconic acid and presented a decreased bacterial cellulose (BC) production due to its restricted glucose utilization. To address this problem, the gene of glucose facilitator protein ( glf ; ZMO0366) was introduced into the knockout strain coupled with the overexpression of the endogenous glucokinase gene ( glk ). The BC yield of the resultant strain increased by 63.63-173.68%, thus reducing the production cost.

This study engineered β-carotene ketolase CrtW and β-carotene hydroxylase CrtZ to improve biosynthesis of astaxanthin in Escherichia coli. Firstly, crtW was randomly mutated to increase CrtW activities on conversion from β-carotene to astaxanthin. A crtW* mutant with A6T, T105A and L239M mutations has improved 5.35-fold astaxanthin production compared with the wild-type control. Secondly, the expression levels of crtW* and crtZ on chromosomal were balanced by simultaneous modulation RBS regions of their genes using RBS library. The strain RBS54 selected from RBS library, directed the pathway exclusively towards the desired product astaxanthin as predominant carotenoid (99%). Lastly, the number of chromosomal copies of the balanced crtW-crtZ cassette from RBS54 was increased using a Cre-loxP based technique, and a strain with 30 copies of the crtW*-crtZ cassette was selected. This final strain DL-A008 had a 9.8-fold increase of astaxanthin production compared with the wild-type control. Fed-batch fermentation showed that DL-A008 produced astaxanthin as predominant carotenoid (99%) with a specific titer of 0.88 g·L -1 without addition of inducer. In conclusion, through constructing crtW mutation, balancing the expression levels between crtW* and crtZ, and increasing the copy number of the balanced crtW*-crtZ cassette, the activities of β-carotene ketolase and β-carotene hydroxylase were improved for conversion of β-carotene to astaxanthin with higher efficiency. The series of conventional and novel metabolic engineering strategies were designed and applied to construct the astaxanthin hetero-producer strain of E. coli, possibly offering a general approach for the construction of stable hetero-producer strains for other natural products., (Copyright © 2020 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.)

Bacterial infections are currently a major concern to human health. Amino acid-based supramolecular polymer hydrogels, which boast intrinsic antibacterial activity, are an important solution due to their good biocompatibility, cost effectiveness, and tunable structural properties. Herein, we reported three types of transparent supramolecular hydrogel with intrinsic antibacterial activity from self-assembly of commercially available Fmoc-tryptophan (Fmoc-W), Fmoc-methionine (Fmoc-M), and Fmoc-tyrosine (Fmoc-Y). The resulting hydrogels selectively inhibited the growth of Gram-positive bacteria. Moreover, the order of antibacterial activity was Fmoc-W hydrogel > Fmoc-M hydrogel > Fmoc-Y hydrogel. The critical aggregation concentration (CAC) values were found at concentrations of approximately 0.0293, 0.1172, and 0.4688 mM for Fmoc-W, Fmoc-M, and Fmoc-Y, respectively. Transmission electron microscope (TEM) images revealed rigid and aligned nanofibers for Fmoc-W hydrogel, while flexible nanofibers for Fmoc-M hydrogel and Fmoc-Y hydrogel. The results indicated that stronger aggregation capability of the gelator and the synergistic nanostructural morphology with more rigid and aligned nanofibers can lead to higher antibacterial activity of its corresponding hydrogel. In addition, the molecular arrangements of Fmoc-amino acids in the hydrogels may also contribute to their antibacterial activity. These results can guide the rational design, fabrication, and future application of other self-assembled amino acid-based hydrogels with excellent antibacterial activity., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Diverse applications of bacterial cellulose (BC) have different requirements in terms of its structural characteristics. culturing Komagataeibacter xylinus CGMCC 2955, BC structure changes with alterations in oxygen tension. Here, the K. xylinus CGMCC 2955 transcriptome was analyzed under different oxygen tensions. Transcriptome and genome analysis indicated that BC structure is related to the rate of BC synthesis and cell growth, and galU is an essential gene that controls the carbon metabolic flux between the BC synthesis pathway and the pentose phosphate (PP) pathway. The CRISPR interference (CRISPRi) system was utilized in K. xylinus CGMCC 2955 to control the expression levels of galU. By overexpressing galU and interfering with different sites of galU sequences using CRISPRi, we obtained strains with varying expression levels of galU (3.20-3014.84%). By testing the characteristics of BC, we found that the porosity of BC (range: 62.99-90.66%) was negative with galU expression levels. However, the crystallinity of BC (range: 56.25-85.99%) was positive with galU expression levels; galU expression levels in engineered strains were lower than those in the control strains. Herein, we propose a new method for regulating the structure of BC to provide a theoretical basis for its application in different fields., (© 2020 Wiley Periodicals, Inc.)

The absence of antibacterial activity of bacterial cellulose (BC) restricts its applications in the biomedical field. To introduce antimicrobial properties into BC, we studied the synthesis, structure, and antimicrobial properties of a novel nanocomposite film comprising BC, graphene oxide (GO), and copper-oxide (CuO) nanosheets. The nanocomposite film was synthesized by incorporating GO-CuO nanohybrids into BC matrix through homogenized blending. The CuO nanosheets, with a length range of 50 nm-200 nm and width range of 20 nm-50 nm, which were uniformly grown on the GO along with even distribution of GO-CuO nanohybrids on the surface of the cellulose fibers. The nanocomposites displayed better antibacterial activity against gram-positive than gram-negative bacteria. BC/GO-CuO nanocomposites showed higher antibacterial activity than BC/CuO. We also elucidated the mechanism of antibacterial activity of the nanocomposites. Further, the nanocomposites exhibited biocompatibility towards mice fibroblast cells. The nanocomposites might serve as an excellent source for development of antibacterial materials., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The combination of high mechanical properties, antibacterial activity and a green synthesis of the polyvinyl alcohol (PVA) based films remains challenging. This study presents a ternary system of PVA films containing bacterial cellulose (BC) and epsilon-polylysine (ε-PL) by a green solution casting method. The prepared composite films showed more than 99% antibacterial properties against both Staphylococcus aureus and Escherichia coli bacteria. Moreover, the films were collected after a single use and were reused twice, which still exhibited strong antibacterial activity. The films showed thermal stability and higher mechanical properties as compared to pure PVA films. In addition, the cytotoxicity of the films was evaluated by MTT assay against NIH 3T3 mouse fibroblast cells. The results showed no toxicity of the films towards tested cells. We believe that these antibacterial films may find applications in active food packaging and biomedical fields., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Many Gram-negative bacteria can regulate gene expression in a cell density-dependent manner via quorum-sensing systems using N -acyl-homoserine lactones (AHLs), which are typical quorum-sensing signaling molecules, and thus modulate physiological characteristics. N -acyl-homoserine lactones are small chemical molecules produced at low concentrations by bacteria and are, therefore, difficult to detect. Here, a biosensor system method and liquid chromatography-tandem mass spectrometry were combined to detect and assay AHL production. As demonstrated by liquid chromatography-tandem mass spectrometry, Gluconacetobacter xylinus CGMCC No. 2955, a Gram-negative acetic acid-producing bacterium and a typical bacterial cellulose (BC) biosynthesis strain, produces six different AHLs, including N -acetyl-homoserine lactone, N -butanoyl-homoserine lactone, N -hexanoyl-homoserine lactone, N -3-oxo-decanoyl-homoserine lactone, N -dodecanoyl-homoserine lactone, and N -tetradecanoyl-homoserine lactone. Gluconacetobacter sp. strain SX-1, another Gram-negative acetic acid-producing bacterium, which can synthesize BC, produces seven different AHLs including N -acetyl-homoserine lactone, N -butanoyl-homoserine lactone, N -hexanoyl-homoserine lactone, N -3-oxo-octanoyl-homoserine lactone, N -decanoyl-homoserine lactone, N -dodecanoyl-homoserine lactone, and N -tetradecanoyl-homoserine lactone. These results lay the foundation for investigating the relationship between BC biosynthesis and quorum-sensing systems.

Bacterial cellulose (BC) has numerous excellent properties but the absence of antibacterial activity restricts its applications in biomedical field. Therefore, in order to introduce the antibacterial characteristics into BC; herein, a facile method for incorporation of ZnO nanoparticles (ZnO-NPs) is presented. BC films were first immersed in zinc nitrate solution, followed by treating with NaOH solution, the BC loaded ZnO nanocomposite films were dried by a sheet former instrument at 80 °C for 20 min. The obtained BC/ZnO nanocomposites were characterized by different techniques. XRD results showed the hexagonal wurtzite structure of ZnO-NPs while FE-SEM results displayed the particle size of ZnO-NPs was ranging from 70 to 100 nm. Thermogravimetric study revealed the thermal stability of nanocomposite films. The nanocomposite exhibited photocatalytic activity and revealed 91% degradation of methyl orange (MO) under UV-irradiation within 2 h. Moreover, the nanocomposites demonstrated significant UV-blocking properties and showed antibacterial activities against tested Gram-positive and Gram-negative bacterial strains. This work provides a simple and novel method for the synthesis of BC/ZnO nanocomposite as a functional biomaterial., (Copyright © 2019. Published by Elsevier B.V.)

Esters are important flavor compounds in alcoholic beverages. Although they are present at trace levels, esters play a key role in the formation of flavors, especially fruity flavors, in beverages. Low ester contents result in bland beer and unpleasant flavor. In this study, three recombinant strains, ethanol O-acyltransferase encoding EEB1 overexpression strain (31194:: EEB1), 2-enoyl thioester reductase encoding ETR1 overexpression strain (31194:: ETR1), and EEB1- ETR1 co-overexpression strain (31194:: EEB1:: ETR1), were constructed. Ethyl hexanoate production by 31194:: EEB1 and 31194:: EEB1:: ETR1 was 106% higher than that by the parental strain. Further, ethyl octanoate production by 31194:: EEB1 and 31194:: EEB1:: ETR1 was enhanced by 47 and 41%, respectively, compared with that of parental strain 31194. However, no difference was observed between 31194:: ETR1 and the parental strain in terms of ethyl hexanoate and ethyl octanoate production. This indicates that although EEB1 overexpression in Saccharomyces pastorianus enhanced ethyl hexanoate and ethyl octanoate production, ETR1 expression levels did not affect the extracellular concentrations of these esters.

The bacterial infections have always a serious problem to public health. Scientists are developing new antibacterial materials to overcome this problem. Polysaccharides are promising biopolymers due to their diverse biological functions, low toxicity, and high biodegradability. Chitin and chitosan have antibacterial properties due to their cationic nature, while cellulose/bacterial cellulose does not possess any antibacterial activity. Moreover, the insolubility of chitin in common solvents, the poor solubility of chitosan in water, and the low mechanical properties of chitosan have restricted their biomedical applications. In order to solve these problems, chemical modifications such as quaternization, carboxymethylation, cationization, or surface modification of these polymers with different antimicrobial agents, including metal and metal oxide nanoparticles, are carried out to obtain new materials with improved physiochemical and biological properties. This mini review describes the recent progress in such derivatives and composites with potential antibacterial applications.

To explore the regulatory factor of light quality affecting exopolysaccharide (EPS) production, transcriptome analysis of Nostoc flagelliforme cells exposed to red light (R), blue light (B), and mixed light (B/R = 15:7) (BR) with white fluorescent light as control was performed. The differentially expressed genes mainly enriched in carbohydrate metabolism and energy metabolism. Significant enrichment in the oxidation-reduction process and energy metabolism indicated that intracellular redox homeostasis was disrupted. An assay of reactive oxygen species (ROS) and malondialdehyde contents demonstrated light quality induced oxidative stress. To illustrate the relationship between ROS level and EPS accumulation, the effects of the exogenous addition of ROS scavenger N-acetyl cysteine and inducer H 2 O 2 on the oxidation-reduction level and EPS production were compared. The results revealed that light quality regulated EPS biosynthesis via the intracellular ROS level directly other than oxidative stress. Understanding such relationships might provide guidance for efficient EPS production to regulate the intracellular redox level.

Nostoc flagelliforme is an edible cyanobacterium with excellent food and herbal values. It has been used as food in China for more than 2000 years. Many studies have been focused on improving the yield and bioactivity of Nostoc flagelliforme polysaccharides although these have ignored the functional properties. In this study, we extracted and purified three polysaccharides (WL-CPS, NaCl-CPS and Glu-CPS) from Nostoc flagelliforme under normal, salt stress and mixotrophic culture conditions, respectively, in order to change the physicochemical properties of polysaccharides with the aim of obtaining better functional properties. Both salt stress and mixotrophic culture conditions increased the specific yield of polysaccharides. Their functional properties were comparatively investigated and the results showed that NaCl-CPS exhibited the highest emulsification activity and flocculation capability, which was also higher than that of some commercial products. In contrast, Glu-CPS exhibited the highest water and oil holding capacities, foaming property, intrinsic viscosity and bile acids binding capacity. Our results indicated that both NaCl-CPS and Glu-CPS could be considered to be functional polysaccharides according to their respective characteristics, which have great potential in numerous applications, such as food, pharmaceutical, cosmetic, chemical and mineral industries. These findings also demonstrated the potential application of the proper regulation of culture conditions in the development of polysaccharides with desired functional properties.

In the present work, novel bacterial cellulose (BC) and chitosan (CS) semi-interpenetrating network (semi-IPN) hydrogels were prepared via blending the slurry of BC with CS solution followed by cross-linking with glutaraldehyde. The structure and properties of BC-CS hydrogels were characterized by different techniques including; FTIR, XRD, FE-SEM, TGA and rotational rheometry. The results indicated cross-linking of chitosan chains by glutaraldehyde while BC was physically connected to network forming semi-IPN hydrogels. Microscopic study of cross-sectional freeze-dried hydrogels showed microporous openings. BC-CS hydrogels exhibited higher thermal stability than pure BC film or CS hydrogel alone. The rheological results presented significant mechanical properties of semi-IPN hydrogels. Moreover, the hydrogels showed antibacterial properties against tested Gram-positive and Gram-negative bacteria. The antibacterial properties were dependent on the ratio of BC to CS. Hydrogels with 20% BC to CS reduced the viable colonies by ~88%. The development of this new class of BC-CS antibacterial, mechanically strong and stable soft-material could be a promising candidate for antibacterial applications., (Copyright © 2018. Published by Elsevier B.V.)

Nostoc flagelliforme is a pioneer organism in the desert and highly resistant to ultraviolet B (UV-B) radiation, while the involved adaptive mechanism has not been fully explored yet. To elucidate the responsive mechanism, two doses of UV-B radiation (low: 1 W/m 2 and high: 5 W/m 2 ) were irradiated for 6 h and 48 h, respectively, and their effects on global metabolism in N. flagelliforme were comprehensively investigated. In this study, we used iTRAQ-based proteomic approach to explore the proteomes of N. flagelliforme, and 151, 172, 124 and 148 differentially expressed proteins were identified under low and high UV-B doses for 6 h and 48 h, respectively. Functional classification analysis showed these proteins were mainly involved in photosynthesis, amino acid metabolism, antioxidant activity and carbohydrate metabolism. Further analysis revealed that UV-B imposed restrictions on primary metabolism including photosynthesis, Calvin cycle, and amino acid metabolism, and cells started defense mechanism through repair of DNA and protein damage, increasing antioxidant activity, and accumulating extracellular polysaccharides to minimize the damage. Moreover, high UV-B dose imposed more severe restrictions and activated stronger defense mechanism compared with low dose. The results would improve the understanding of molecular mechanisms of UV-B-stress adaption in N. flagelliforme.

Three polysaccharides (WL-CPS-1, NaCl-CPS-1 and Glu-CPS-1) were extracted and purified from Nostoc flagelliforme under normal, salt stress and mixotrophic culture conditions respectively. Their physicochemical properties and antioxidant activities were investigated. WL-CPS-1, NaCl-CPS-1 and Glu-CPS-1 chemical composition differed in sugar and uronic acid contents, and they were composed of nine constituent monosaccharides and one uronic acid with different ratios, with the average molecular weights of 1.02 × 10 3 , 1.12 × 10 3 and 1.33 × 10 3 kDa, respectively. They presented similar fourier transform infrared spectra, but different surface morphology, chain length and branching. Antioxidant assay showed that they all exhibited strong scavenging activity on ABTS + and hydroxyl radicals and moderate activity on DPPH radical. Glu-CPS-1 exhibited the highest antioxidant activity suggested culture conditions could regulate the bioactivity through influencing the structure and properties. These findings demonstrated the potential application of proper regulation of culture conditions in the development of polysaccharides with high antioxidant activity., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Nostoc flagelliforme is a pioneer organism in the desert and exerts important ecological functions. The habitats of N. flagelliforme are characterized by intense solar radiation, while the ultraviolet B (UV-B) tolerance has not been fully explored yet. To evaluate the physiological responses of N. flagelliforme to UV-B radiation, three intensities (1 W m -2 , 3 W m -2 and 5 W m -2 ) were used, and the changes in photosynthetic pigments, cell morphology, mycosporine-like amino acids (MAAs) synthesis and cell metabolism were comparatively investigated. Under high UV-B intensity or long term radiation, chlorophyll a , allophycocyanin and phycocyanin were greatly decreased; scanning electron microscope observations showed that cell morphology significantly changed. To reduce the damage, cells synthesized a large amount of carotenoid. Moreover, three kinds of MAAs were identified, and their concentrations varied with the changes of UV-B intensity. Under 1 W m -2 radiation, cells synthesized shinorine and porphyra-334 against UV-B, while with the increase of intensity, more shinorine turned into asterine-330. Metabolite profiling revealed the contents of some cytoprotective metabolites were greatly increased under 5 W m -2 radiation. The principal component analysis showed cells exposed to UV-B were metabolically distinct from the control sample, and the influence on metabolism was particularly dependent on intensity. The results would improve the understanding of physiological responses of N. flagelliforme to UV-B radiation and provide an important theoretical basis for applying this organism to control desertification., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The relationship between monosaccharide composition of Nostoc flagelliforme extracellular polysaccharide (EPS) and activities of EPS synthesis enzymes under various carbon sources, nitrogen sources and light culture condition was investigated. Culture conditions showed significant influences on both monosaccharide composition and related enzyme activities. Under both carbon and nitrogen sources conditions, mannose mole percentage was increased with the increase of initial mole ratio of C/N and positively related to fructose-1, 6-bisphosphatase activity, and glucuronic acid and galactose mole percentages were positively correlated with UDP-glucose dehydrogenase, while arabinose and rhamnose mole percentages were negatively associated with UDP-glucose pyrophosphorylase. Different correlation between monosaccharide composition and enzymes activity from carbon and nitrogen sources conditions was found under light condition. These findings will be helpful to establish a novel fermentation process aimed to produce the N. flagelliforme EPS with desired monosaccharide composition., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

In this study, bacterial cellulose (BC) was used as a matrix to synthesize graphene oxide/Titanium dioxide (GOTiO 2 )-based hybrid materials. It was indicated by X-ray diffraction and selected area electron diffraction that the crystal structure of GOTiO 2 was a mixed phase containing anatase and rutile. TiO 2 nanoparticles were of 10-30nm diameters and densely anchored on graphene oxide sheets. Superior photocatalytic performance of the GOTiO 2 was achieved under near UV excitation. The photocatalytic efficiency was optimized through controlling an appropriate calcined temperature. The obtained GOTiO 2 nanoparticles were filled into porous BC matrix (GOTiO 2 /BC), and the photocatalytic properties of GOTiO 2 nanoparticles were well maintained. Consistent with photocatalytic performance of TiO 2 , GOTiO 2 /BC generated reactive oxygen species after near ultraviolet irradiation. No dark cytotoxicity was observed at the long incubation time. In parallel, following exposure of Staphylococcus aureus cells to GOTiO 2 and irradiation, a significant decrease in cell viability, as well as an increased production of reactive oxygen species was observed, which induced cellular death. The results indicated that GOTiO 2 /BC possess an excellent photodynamic antibacterial activity., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Background: Enrichment culture was applied to obtain microbial consortium from activated sludge samples collected from biodegradation system, a chemical fiber plant in Hebei Province, China. Bacterial composition and community dynamic variation were assessed employing denaturing gradient gel electrophoresis fingerprinting technology based on amplified 16S rRNA genes in the entire process of enrichment culture for viscose fiber wastewater., Results: Four bacteria named as VF01, VF02, VF03, and VF04 were isolated from the microbial consortium adopting the spray-plate method. The DNA bands of these four bacteria were corresponded to the predominant DNA bands in the electrophoresis pattern. VF01, VF02, VF03, and VF04 were phylogenetically closed to Bacillus licheniformis , Bacillus subtilis , Paracoccus tibetensis , and Pseudomonas sp. by sequence analysis, respectively. The degradation effects for COD Cr of single isolated strain, mixed strains, and microbial consortium (VF) originally screened from viscose fiber wastewater were determined. The degradation ability was as follows: microbial consortium (VF) > mixed strains > single isolated strain. Microbial consortium (VF) showed the optimum degradation rate of COD Cr of 87% on 14th day. Degradation of pollutants sped up by bio-augmentation of four strains. The molecular weight distribution of organic matter showed that viscose fiber wastewater contained a certain amount of large molecular organic matter, which could be decomposed into smaller molecular substances by microbial consortium (VF)., Conclusions: The microbial consortium (VF) obtained from enrichment culture exhibited great potential for COD Cr degradation. The screened strains had bio-augmentation functions and the addition of a mixture of four bacteria could speed up the degradation rate of pollutants.

The effects of a direct current (DC) electric field on the growth and metabolism of Gluconacetobacter xylinus were investigated in static culture. When a DC electric field at 10 mA was applied using platinum electrodes to the culture broth, bacterial cellulose (BC) production was promoted in 12 h but was inhibited in the last 12 h as compared to the control (without DC electric field). At the cathode, the presence of the hydrogen generated a strong reductive environment that is beneficial to cell growth. As compared to the control, the activities of glycolysis and tricarboxylic acid cycle, as well as BC productivity were observed to be slightly higher in the first 12 h. However, due to the absence of sufficient oxygen, lactic acid was accumulated from pyruvic acid at 18 h, which was not in favor of BC production. At the anode, DC inhibited cell growth in 6 h when compared to the control. The metabolic activity in G. xylinus was inhibited through the suppression of the tricarboxylic acid cycle and glycolysis. At 18-24 h, cell density was observed to decrease, which might be due to the electrolysis of water that significantly dropped the pH of cultural broth far beyond the optimal range. Meanwhile, metabolites for self-protection were accumulated, for instance proline, glutamic acid, gluconic acid, and fatty acids. Notably, the accumulation of gluconic acid and lactic acid made it a really tough acid stress to cells at the anode and finally led to depression of cell growth.

Graphene oxide (GO) has an attracting and ever-growing interest in various research fields for its fascinating nanostructures. In this study, bacterial cellulose (BC) was used as a matrix to synthesize GO-based materials by a mechanical mixing method. The modification of GO with PEI significantly improved the bonding force between GO nanofillers and BC matrix. The morphology of the nanocomposites had a significant effect on the mechanical properties, hydrophilic properties as well as the antibacterial activity. After the modification, the GO-PEI/BC showed a strong antimicrobial effect on Saccharomyces cerevisiae due to the effective direct contacts between the nanofillers of the composites and the cell surfaces. This study demonstrates that the morphology of the nanocomposites has a great effect on physiochemical properties and the interactions between the microorganism and the nanocomposites., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Filamentous Nostoc flagelliforme form colloidal complex, with beaded cells interacting with other bacteria embedded in the complex multilayer sheath. However, the species of bacteria in the sheath and the interaction between N. flagelliforme and associated bacteria remain unclear. In this study, PCR-denaturing gradient gel electrophoresis (DGGE) was used to investigate the bacterial communities of N. flagelliforme from three regions of China. DGGE patterns showed variations in all samples, exhibiting 25 discrete bands with various intensities. The diversity index analysis of bands profiles suggested the high similarity of bacterial communities to each other but also the dependence of microbial composition on each location. Phylogenetic affiliation indicated that the majority of the sequences obtained were affiliated with Actinobacteria, Cyanobacteria, Proteobacteria, Acidobacteria, Bacteroidetes, of which Cyanobacteria was dominant, followed the Proteobacteria. Members of the genus Nostoc were the most abundant in all samples. Rhizobiales and Actinobacteria were identified, whereas, Craurococcus, Caulobacter, Pseudomonas, Terriglobus and Mucilaginibacter were also identified at low levels. Through comparing the bacterial composition of N. flagelliforme from different regions, it was revealed that N. flagelliforme could facilitate the growth of other microorganisms including both autotrophic bacteria and heterotrophic ones and positively contributed to their harsh ecosystems. The results indicated N. flagelliforme played an important role in diversifying the microbial community composition and had potential application in soil desertification.

Cross-linked enzyme aggregate (CLEA) technology has been regarded as an effective carrier-free immobilization method. This method is very attractive due to its simplicity and robustness, as well as for the possibility of using the crude enzyme extract and the opportunity to co-immobilize multiple different enzymes. The resulting CLEAs generally exhibit high catalyst productivities, improved storage and operational stability and are easy to recycle. Nowadays, although the technology has been applied to various enzymes, some undesirable properties have limited its further application. To overcome these limitations, novel strategies have been developing in recent years. This mini-review focuses on process optimization, new improved strategies and the latest advances on CLEAs technology.

Sensory evaluation is regarded as a necessary procedure to ensure a reproducible quality of beer. Meanwhile, high-throughput analytical methods provide a powerful tool to analyse various flavour compounds, such as higher alcohol and ester. In this study, the relationship between flavour compounds and sensory evaluation was established by non-linear models such as partial least squares (PLS), genetic algorithm back-propagation neural network (GA-BP), support vector machine (SVM). It was shown that SVM with a Radial Basis Function (RBF) had a better performance of prediction accuracy for both calibration set (94.3%) and validation set (96.2%) than other models. Relatively lower prediction abilities were observed for GA-BP (52.1%) and PLS (31.7%). In addition, the kernel function of SVM played an essential role of model training when the prediction accuracy of SVM with polynomial kernel function was 32.9%. As a powerful multivariate statistics method, SVM holds great potential to assess beer quality., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Extraction and recovery of protein from abundant plant biomass is one potential way to improve the economic feasibility of biorefineries. However, valorization of the protein fraction is challenging due to its low yield (kg protein extraction/kg biomass). In order to reveal the limiting operation parameters, the alkaline extraction process of protein from Caragana korshinskii Kom. was investigated by an integrative analysis of kinetics and thermodynamics. Both a two-site kinetic extraction model and a second-order model indicated that particle size is the most pivotal factor affecting protein extraction yield. In a two-site model, most proteins are extracted quickly from broken cells, while protein removal from the intact cells takes much longer; these are the faster and slower processes, respectively. A decrease of particle size from 20-40 to 60-80 mesh resulted in a decrease of C2 (protein yield in the slower process) from 14.02 to 7.32 mg g(-1), but a great increase of C1 (protein yield in the faster process) from 20.61 to 59.07 mg g(-1) . However, the protein yield was dominated by the faster process when the average particle size is under 80 mesh. The maximum initial extraction rate was 72.20 mg g(-1) min(-1) with the particle size of 60-80 mesh, almost ninefold of that with 20-40 mesh. Thermodynamic analysis revealed that the enthalpy change (ΔH) and entropy change (ΔS) in the protein extraction process were calculated as 21.08 kJ mol(-1) and 84.76 J K(-1), respectively. The standard free energy (ΔG) had a magnitude from -3.77 to -5.46, suggesting that the extraction process was spontaneous and physically feasible., (© 2014 Wiley Periodicals, Inc.)

The application of antibiotic treatment with assistance of metabolomic approach in axenic isolation of cyanobacterium Nostoc flagelliforme was investigated. Seven antibiotics were tested at 1-100 mg L(-1), and order of tolerance of N. flagelliforme cells was obtained as kanamycin > ampicillin, tetracycline > chloromycetin, gentamicin > spectinomycin > streptomycin. Four antibiotics were selected based on differences in antibiotic sensitivity of N. flagelliforme and associated bacteria, and their effects on N. flagelliforme cells including the changes of metabolic activity with antibiotics and the metabolic recovery after removal were assessed by a metabolomic approach based on gas chromatography-mass spectrometry combined with multivariate analysis. The results showed that antibiotic treatment had affected cell metabolism as antibiotics treated cells were metabolically distinct from control cells, but the metabolic activity would be recovered via eliminating antibiotics and the sequence of metabolic recovery time needed was spectinomycin, gentamicin > ampicillin > kanamycin. The procedures of antibiotic treatment have been accordingly optimized as a consecutive treatment starting with spectinomycin, then gentamicin, ampicillin and lastly kanamycin, and proved to be highly effective in eliminating the bacteria as examined by agar plating method and light microscope examination. Our work presented a strategy to obtain axenic culture of N. flagelliforme and provided a method for evaluating and optimizing cyanobacteria purification process through diagnosing target species cellular state.

Phenylalanine ammonia lyase (PAL) catalyzes the nonoxidative deamination of l-phenylalanine to form trans-cinnamic acid and a free ammonium ion. It plays a major role in the catabolism of l-phenylalanine. The presence of PAL has been reported in diverse plants, some fungi, Streptomyces and few Cyanobacteria. In the past two decades, PAL has gained considerable significance in several clinical, industrial and biotechnological applications. Since its discovery, much knowledge has been gathered with reference to the enzyme's importance in phenyl propanoid pathway of plants. In contrast, there is little knowledge about microbial PAL. Furthermore, the commercial source of the enzyme has been mainly obtained from the fungi. This study focuses on the recent advances on the physiological role of microbial PAL and the improvements of PAL biotechnological production both from our laboratory and many others as well as the latest advances on the new applications of microbial PAL.

The potential impact of transgene escape on the environment and food safety is a major concern to the scientists and public. This work aimed to assess the effect of intein-mediated gene splitting on containment of transgene flow. Two fusion genes, EPSPSn-In and Ic-EPSPSc, were constructed and integrated into N. tabacum, using Agrobacterium tumefaciens-mediated transformation. EPSPSn-In encodes the first 295 aa of the herbicide resistance gene 5-enolpyruvyl shikimate-3-phosphate synthase (EPSPS) fused with the first 123 aa of the Ssp DnaE intein (In), whereas Ic-EPSPSc encodes the 36 C-terminal aa of the Ssp DnaE intein (Ic) fused to the rest of EPSPS C terminus peptide sequences. Both EPSPSn-In and Ic-EPSPSc constructs were introduced into the same N. tabacum genome by genetic crossing. Hybrids displayed resistance to the herbicide N-(phosphonomethyl)-glycine (glyphosate). Western blot analysis of protein extracts from hybrid plants identified full-length EPSPS. Furthermore, all hybrid seeds germinated and grew normally on glyphosate selective medium. The 6-8 leaf hybrid plants showed tolerance of 2000 ppm glyphosate in field spraying. These results indicated that functional EPSPS protein was reassembled in vivo by intein-mediated trans-splicing in 100% of plants. In order to evaluate the effect of the gene splitting technique for containment of transgene flow, backcrossing experiments were carried out between hybrids, in which the foreign genes EPSPSn-In and Ic-EPSPSc were inserted into different chromosomes, and non-transgenic plants NC89. Among the 2812 backcrossing progeny, about 25% (664 plantlets) displayed glyphosate resistance. These data indicated that transgene flow could be reduced by 75%. Overall, our findings provide a new and highly effective approach for biological containment of transgene flow.