A comparative study for petroleum removal capacities of the bacterial consortia entrapped in sodium alginate,sodium alginate/poly(vinyl alcohol),and bushnell haas agar

The purpose of this study was to identify and compare the degradation efficiencies of free and entrapped bacterial consortia(Staphylococcus capitis CP053957.1 and Achromobacter marplatensis MT078618.1)to different polymers such as Sodium Alginate(SA),Sodium Alginate/Poly(Vinyl Alcohol)(SA/PVA),and Bushnell Haas Agar(BHA).In addition to SA and SA/PVA,which are cost-effective,non-toxic and have different functional groups,BHA,which is frequently encountered in laboratory-scale studies but has not been used as an entrapment material until now.Based on these,the polymers with different surface morphologies and chemical compositions were analyzed by SEM and FT-IR.While the petroleum removal efficiency was higher with the entrapped bacterial consortia than with the free one,BHA-entrapped bacterial consortium enhanced the petroleum removal more than SA and SA/PVA.Accordingly,the degradation rate of bacterial consortia entrapped with BHA was 2.039 day^(-1),SA/PVA was 1.560,SA was 0.993,the half-life period of BHA-entrapped bacterial consortia is quite low(t_(1/2)=0.339)compared with SA(t_(1/2)=0.444)and SA/PVA(t_(1/2)=0.697).The effects of the four main factors such as:amount of BHA(0.5,1,1.5,2,2.5,3 g),disc size(4,5,6,7,8 mm),inoculum concentration(1,2.5,5,7.5,10 mL),and incubation period on petroleum removal were also investigated.The maximum petroleum removal(94.5%)was obtained at≥2.5 mL of bacterial consortium entrapped in 2 g BHA with a 7 mm disc size at 168 h and the results were also confirmed by statistical analysis.Although a decrease was observed during the reuse of bacterial consortium entrapped in BHA,the petroleum removal was still above 50%at 10th cycle.Based on GC-MS analysis,the removal capacity of BHA-entrapped consortium was over 90%for short-chain n-alkanes and 80%for medium-chain n-alkanes.Overall,the obtained data are expected to provide a potential guideline in cleaning up the large-scale oil pollution in the future.Since there has been no similar study investigating petroleum removal with the bacterial consortia entrapped with BHA,this novel entrapment material can potentially be used in the treatment of petroleum pollution in advanced remediation studies.

Eco-friendly calcium alginate microspheres enable enhanced profile control and oil displacement

Polymer microspheres(PMs),such as polyacrylamide,have been widely applied for enhanced oil recovery(EOR),yet with environmental concerns.Here,we report a microfluid displacement technology containing a bio-based eco-friendly material,i.e.,calcium alginate(CaAlg)microspheres for EOR.Two dominant mechanisms responsible for EOR over Ca Alg fluid have been verified,including the microscopic oil displacement efficacy augmented by regulating capillary force(determined by the joint action of interfacial tension and wettability between different phases)and macroscopic sweep volume increment through profile control and mobility ratio reduction.This comprehensive effectiveness can be further impacted when the CaAlg microsphere is embellished ulteriorly by using appropriate amount of sodium dodecyl sulfonate(SDS).The core flooding and nuclear magnetic resonance(NMR)tests demonstrate that CaAlg-SDS microsphere can balance the interphase property regulation(wettability alteration and IFT reduction)and rheology properties,enabling simultaneous profile control and oil displacement.Excessive introduction of SDS will have a negative impact on rheological properties,which is not favored for EOR.Our results show that the involvement of 4-m M SDS will provide the best behavior,with an EOR rate of 34.38%.This cost-effective and environmentally-friendly bio-microspherebased microfluidic displacement technology is expected to achieve“green”oil recovery in future oilfield exploitation.

Constructing a biofunctionalized 3D-printed gelatin/sodium alginate/chitosan tri-polymer complex scaffold with improvised biological andmechanical properties for bone-tissue engineering

Sodium alginate(SA)/chitosan(CH)polyelectrolyte scaffold is a suitable substrate for tissue-engineering application.The present study deals with further improvement in the tensile strength and biological properties of this type of scaffold to make it a potential template for bone-tissue regeneration.We experimented with adding 0%–15%(volume fraction)gelatin(GE),a protein-based biopolymer known to promote cell adhesion,proliferation,and differentiation.The resulting tri-polymer complex was used as bioink to fabricate SA/CH/GEmatrices by three-dimensional(3D)printing.Morphological studies using scanning electron microscopy revealed the microfibrous porous architecture of all the structures,which had a pore size range of 383–419μm.X-ray diffraction and Fourier-transform infrared spectroscopy analyses revealed the amorphous nature of the scaffold and the strong electrostatic interactions among the functional groups of the polymers,thereby forming polyelectrolyte complexes which were found to improve mechanical properties and structural stability.The scaffolds exhibited a desirable degradation rate,controlled swelling,and hydrophilic characteristics which are favorable for bone-tissue engineering.The tensile strength improved from(386±15)to(693±15)kPa due to the increased stiffness of SA/CH scaffolds upon addition of gelatin.The enhanced protein adsorption and in vitro bioactivity(forming an apatite layer)confirmed the ability of the SA/CH/GE scaffold to offer higher cellular adhesion and a bone-like environment to cells during the process of tissue regeneration.In vitro biological evaluation including the MTT assay,confocal microscopy analysis,and alizarin red S assay showed a significant increase in cell attachment,cell viability,and cell proliferation,which further improved biomineralization over the scaffold surface.In addition,SA/CH containing 15%gelatin designated as SA/CH/GE15 showed superior performance to the other fabricated 3D structures,demonstrating its potential for use in bone-tissue engineering.

Alginate oligosaccharide-mediated butyrate-HIF-1α axis improves skin aging in mice

The“gut-skin”axis has been proved and is considered as a novel therapy for the prevention of skin aging.The antioxidant efficacy of oligomannonic acid(MAOS)makes it an intriguing target for use to improve skin aging.The present study further explored whereby MAOS-mediated gut-skin axis balance prevented skin aging in mice.The data indicated the skin aging phenotypes,oxidative stress,skin mitochondrial dysfunction,and intestinal dysbiosis(especially the butyrate and HIF-1a levels decreased)in aging mice.Similarly,fecal microbiota transplantation(FMT)from aging mice rebuild the aging-like phenotypes.Further,we demonstrated MAOS-mediated colonic butyrate-HIF-1a axis homeostasis promoted the entry of butyrate into the skin,upregulated mitophagy level and ultimately improving skin aging via HDAC3/PHD/HIF-1a/mitophagy loop in skin of mice.Overall,our study offered a better insights of the effectiveness of alginate oligosaccharides(AOS),promised to become a personalized targeted therapeutic agents,on gut-skin axis disorder inducing skin aging.

Chitosan/Sodium Alginate Multilayer pH-Sensitive Films Based on Layer-by-Layer Self-Assembly for Intelligent Packaging

The abuse of plastic food packaging has brought about severe white pollution issues around the world.Developing green and sustainable biomass packaging is an effective way to solve this problem.Hence,a chitosan/sodium alginate-based multilayer film is fabricated via a layer-by-layer(LBL)self-assembly method.With the help of superior interaction between the layers,the multilayer film possesses excellent mechanical properties(with a tensile strength of 50 MPa).Besides,the film displays outstanding water retention property(blocking moisture of 97.56%)and ultraviolet blocking property.Anthocyanin is introduced into the film to detect the food quality since it is one natural plant polyphenol that is sensitive to the pH changes ranging from 1 to 13 in food when spoilage occurs.It is noted that the film is also bacteriostatic which is desired for food packaging.This study describes a simple technique for the development of advanced multifunctional and fully biodegradable food packaging film and it is a sustainable alternative to plastic packaging.

Fabrication of Core-Shell Hydrogel Bead Based on Sodium Alginate and Chitosan for Methylene Blue Adsorption

A novel core-shell hydrogel bead was fabricated for effective removal of methylene blue dye from aqueous solutions.The core,made of sodium alginate-g-polyacrylamide and attapulgite nanofibers,was cross-linked by Calcium ions(Ca^(2+)).The shell,composed of a chitosan/activated carbon mixture,was then coated onto the core.Fourier transform infrared spectroscopy confirmed the grafting polymerization of acrylamide onto sodium alginate.Scanning electron microscopy images showed the core-shell structure.The core exhibited a high water uptake ratio,facilitating the diffusion of methylene blue into the core.During the diffusion process,the methylene blue was first adsorbed by the shell and then further adsorbed by the core.Adsorption tests showed that the coreshell structure had a larger adsorption capacity than the core alone.The shell effectively enhanced the adsorption capacity to methylene blue compared to the single core.Methylene blue was adsorbed by activated carbon and chitosan in the shell,and the residual methylene blue diffused into the core and was further adsorbed.

Physiological and Transcriptome Analysis Illuminates the Molecular Mechanisms of the Drought Resistance Improved by Alginate Oligosaccharides in Triticum aestivum L.

Alginate oligosaccharides(AOS)enhance drought resistance in wheat(Triticum aestivum L.),but the definite mechanisms remain largely unknown.The physiological and transcriptome responses of wheat seedlings treated with AOS were analyzed under drought stress simulated with polyethylene glycol-6000.The results showed that AOS promoted the growth of wheat seedlings and reduced oxidative damage by improving peroxidase and superoxide dismutase activities under drought stress.A total of 10,064 and 15,208 differentially expressed unigenes(DEGs)obtained from the AOS treatment and control samples at 24 and 72 h after dehydration,respectively,were mainly enriched in the biosynthesis of secondary metabolites(phenylpropanoid biosynthesis,flavonoid biosynthesis),carbohydrate metabolism(starch and sucrose metabolism,carbon fixation in photosynthetic organisms),lipid metabolism(fatty acid elongation,biosynthesis of unsaturated fatty acids,alpha-linolenic acid metabolism,cutin,suberine and wax biosynthesis),and signaling transduction pathways.The up-regulated genes were related to,for example,chlorophyll a-b binding protein,amylosynthease,phosphotransferase,peroxidase,phenylalanine ammonia lyase,flavone synthase,glutathione synthetase.Signaling molecules(including MAPK,plant hormones,H_(2)O_(2) and calcium)and transcription factors(mainly including NAC,MYB,MYB-related,WRKY,bZIP family members)were involved in the AOS-induced wheat drought resistance.The results obtained in this study help underpin the mechanisms of wheat drought resistance improved by AOS,and provides a theoretical basis for the application of AOS as an environmentally sustainable biological method to improve drought resistance in agriculture.

Preparation and release of curcumin/silk fibroin/sodium alginate film

The aim of this study was to prepare silk fibroin/sodium alginate composite film containing curcumin by casting method.Orthogonal test was used to optimize the formulation according to the values of tensile strength and elongation at break.The release of curcumin in the optimal film was studied in order to explore its application as wound dressing.The results showed that the optimum composition of curcumin/silk fibroin/sodium alginate composite film was as follows:Silk fibroin(70 mg/mL)2.7 g,sodium alginate(24 mg/mL)0.84 g,span 40(5.0 mg/mL)0.4 g,glycerol(3.75%,V/V)3 mL,curcumin(0.2 mg/mL)0.016 g.The optimum film showed the tensile strength and the elongation at break was(0.628±0.032)MPa and(0.794±0.046)%,respectively.

Application of alginate in inflammatory bowel disease

Inflammatory bowel disease(IBD)represents a chronic inflammatory condition profoundly impacting the gastrointestinal tract.Its prevalence has markedly risen in both developed and developing nations over recent decades.Despite the absence of definitive etiological elucidation,therapeutic strategies predominantly revolve around pharmacological interventions aimed at symptom mitigation.Alginate(AG)is a polysaccharide of marine origin that has garnered significant attention due to its inherent biocompatibility,pH sensitivity,and cross-linking.Its exploration within drug delivery systems for IBD treatment stems from its natural sourcing,non-cytotoxic nature,and economic viability.Notably,AG demonstrates facile interpolymeric cross-linking,facilitating the formation of a cohesive network conducive to sustained drug release kinetics.AG-based carrier systems for sustained drug release,and targeted drug delivery have been widely studied.This article reviews the pathogenesis of IBD and the current drugs,AG-based drug delivery systems and their properties in alleviating IBD.The prospect of further development of AG in the field of biopharmaceutical and drug delivery is prospected.

Enzymatically prepared alginate oligosaccharides improve broiler chicken growth performance by modulating the gut microbiota and growth hormone signals

Background Alginate oligosaccharide(AOS)holds great potential as a novel feed supplement in farm animals.However,the effects of AOS on chicken health and the underlying mechanisms are not fully understood.This study aimed to optimize the enzymatic preparation of AOS by using bacterial alginate lyases expressed in yeast,investigate the effects of the prepared AOS on the growth performance and gut health of broiler chickens,and reveal the underlying mechanisms.Results Five alginate lyases from bacteria were cloned into Pichia pastoris GS115 and the alginate lyase PDE9 was expressed at relatively high yield,activity and stability in P.pastoris.Animal trials were carried out using 3201-day-old male Arbor Acres broilers(four groups;8 replicates/group×10 chicks/replicate)receiving either a basal diet or the same diet supplemented with 100,200 and 400 mg/kg PDE9-prepared AOS for 42 d.The results showed that dietary supplementation of 200 mg/kg AOS displayed the highest activity in promoting the birds’ADG and ADFI(P<0.05).AOS ameliorated the intestinal morphology,absorption function and barrier function,as indicated by the enhanced(P<0.05)intestinal villus height,maltase activity,and the expression of PEPT,SGLT1,ZNT1,and occludin.AOS also increased serum insulin-like growth factor-1,ghrelin(P<0.05),and growth hormone(P<0.1).Moreover,the concentrations of acetate,isobutyrate,isovalerate,valerate,and total SCFAs in cecum of birds fed AOS were significantly higher than the control birds(P<0.05).Metagenomic analysis indicated that AOS modulated the chicken gut microbiota structure,function,and microbial interactions and promoted the growth of SCFAs-producing bacteria,for example,Dorea sp.002160985;SCFAs,especially acetate,were found positively correlated with the chicken growth performance and growth-related hormone signals(P<0.05).We further verified that AOS can be utilized by Dorea sp.to grow and to produce acetate in vitro.Conclusions We demonstrated that the enzymatically produced AOS effectively promoted broiler chicken growth performance by modulating the chicken gut microbiota structure and function.For the first time,we established the connections among AOS,chicken gut microbiota/SCFAs,growth hormone signals and chicken growth performance.

An intermediate poly-dopamine layer for alginate coating on high-purity magnesium to achieve corrosion mitigation

Although magnesium(Mg)and its alloys are proposed as the next generation orthopedics transplanted materials,their clinical applications are limited by the fast degradation.To reduce the degradation rate,a strong adhesion poly-dopamine(PDA)layer was introduced as an intermediate layer for the subsequent alginate(ALG)spin-coating on high-purity Mg.The surface morphology and chemical composition were detected by scanning electron microscope,energy disperse spectroscopy,and Fourier transform infrared spectroscopy.The corrosion resistances of all samples were evaluated by electrochemical and 10-day immersion tests in Hanks’balanced salt solution.Our results suggest that the thickness of the fabricated PDA/ALG composite coating is 8.58±0.65μm,and the intermediate PDA layer evidently enhances the adhesion between the substrate and ALG coating.The corrosion current density of Mg coated with the PDA/ALG composite coating decreases more than 10 times compared to that of the Mg substrate,and the charge transfer resistance is 12 times bigger than that of the bare Mg,which indicates the improved corrosion resistance.Moreover,the mechanism of corrosion protection of the composite coating is also discussed.

3D-printed engineered bacteria-laden gelatin/sodium alginate composite hydrogels for biological detection of ionizing radiation

Nuclear safety is a global growing concern,where ionizing radiation(IR)is a major injury factor resulting in serious damage to organisms.The detection of IR is usually conducted with physical dosimeters;however,biological IR detection methods are deficient.Here,a living composite hydrogel consisting of engineered bacteria and gelatin/sodium alginate was 3D-printed for the biological detection of IR.Three strains of PrecA::egfp gene circuit-containing engineered Escherichia coli were constructed with IR-dependent fluorescence,and the DH5αstrain was finally selected due to its highest radiation response and fluorescence.Engineered bacteria were loaded in a series of gelatin/sodium alginate matrix hydrogels with different rheology,3D printability and bacterial applicability.A high-gelatin-content hydrogel containing 10%gelatin/1.25%sodium alginatewas optimal.The optimal living composite hydrogelwas 3D-printedwith the special bioink,which reported significant green fluorescence underγ-ray radiation.The living composite hydrogel provides a biological strategy for the detection of environmental ionizing radiation.

Fabrication of alginate-based microspheres with cellular structure for tuning ammonium dinitramide performance

Recently,an emerging category green of energetic material ammonium dinitramide(ADN)has exhibited promising application in propellants due to its outstanding merits in energy release and environmental friendliness.It can be considered to substitute traditional oxidizer of ammonium perchlorate(AP)in military systems and aerospace.In this paper,a novel spherical energetic composite ADN/copper alginate(CA)with a microporous structure was designed and prepared by the W/O gel emulsion method,and a desirable porous microsphere structure was obtained.Multiple characterization techniques were used to investigate the structure and properties of ADN/CA composites.The results showed that ADN crystals were homogeneously encapsulated in an alginate-gel matrix.Thermal decomposition temperature was reduced to 151.7℃compared to ADN,while the activation energy of them was reduced from 129.73 k J/mol(ADN)to 107.50 k J/mol(ADN/CA-4).In addition,as-prepared samples had lower impact and frictional sensitivity than ADN.The mechanism of sensitivity reduction and decomposition are also discussed.Constant-volume combustion tests show that peak pressure of the ADN/CA-4 achieves 253.4 k Pa and pressurization rate of 2750.4 k Pa/s.Hence,this has a promising application in improving the combustion performance and safety performance of solid propellants.

Preparation of sodium alginate gel microspheres catalysts and its high catalytic performance for treatment of ciprofloxacin wastewater

The discharge of the antibiotic wastewater has increased dramatically in our country with the development of medical science and wide application of antibiotic,resulting in serious harm to human body and ecological environment.In this work,ciprofloxacin(CIP)was selected as one of typical antibiotics and heterogeneous Fenton-like catalysts were prepared for the treatment of ciprofloxacin wastewater.The sodium alginate(SA)gel microspheres catalysts were prepared by polymerization method using double metal ions of Fe^(3+)and Mn^(2+)as cross-linking agents.Preparation conditions such as metal ions concentration,mass fraction of SA,polymerization temperature and dual-metal ions as crosslinking agent were optimized.Moreover,the effects of operating conditions such as initial concentration of CIP,pH value and catalyst dosage on CIP removal were studied.The kinetic equation showed that the effect of the initial concentration of CIP on the degradation rate was in line with second-order kinetics,and the effects of catalyst dosage and pH value on the degradation rate of CIP were in line with first-order kinetics.The SA gel microspheres catalysts prepared by dual-metal ions exhibited a high CIP removal and showed a good reusability after six recycles.The SA gel microspheres catalysts with an easy recovery performance provided an economical and efficient method for the removal of antibiotics in the future.

Alginate/gelatin/boron-doped hydroxyapatite-coated Ti implants:in vitro and in vivo evaluation of osseointegration

In this study,boron-doped hydroxyapatite(BHT)-loaded alginate/gelatin-based(A/G)hydrogel coating on Ti was fabricated to support bone integration through triggering osteoinduction,vascularization and immunomodulation.Initially,highly reproducible,cheap and time-effective BHT was produced,which significantly promoted higher osteogenic and angiogenic maturation,while a mild innate immune response was observed.The immense potential of BHT was evidenced by the production of a gap-filling A/G/BHT interphase on Ti implants to mimic the osseous extracellular matrix to achieve functional bridging and exert control over the course of innate immune response.We initially aminosilanized the implant surface using 3-aminopropyl triethoxysilane,and then coated it with 0.25%w/v alginate with 20 mM 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide to allowthe A/G/BHT pre-gel to disperse evenly and covalently attach on the surface.The pre-gel was added with 0.2 M NaCl to homogeneously blend BHT in the structure without inducing ionic crosslinking.Then,the coated implants were freeze-dried and stored.The coated layer demonstrated high cohesive and adhesive strength,and 8-month-long shelf-life at room temperature and normal humidity.The A/G/BHT was able to coat an irregularly shaped Ti implant.Osteoblasts and endothelial cells thrived on the A/G/BHT,and it demonstrated greatly improved osteogenic and angiogenic capacity.Moreover,A/G/BHT maintained macrophage viability and generated an acute increase in immune response that could be resolved rapidly.Finally,A/G/BHT was shown to induce the robust integration of implant in a rabbit femur osteochondral model within 2months.Therefore,we concluded that A/G/BHT coatings could serve as amultifunctional reservoir,promoting the strong and rapid osseointegration of metallic implants.

Diversity of culturable alginate lyase-excreting bacteria associated with Sargassum

Large numbers of bacteria live on the surface of various brown algae and can produce alginate lyases to consume alginate,an important component of the cell wall of brown algae.Sargassum is a genus of the largest canopyforming brown algae of more than 150 species,which are widely distributed in tropical and subtropical environments.However,our knowledge about the epiphytic bacteria and the alginate lyase-excreting bacteria from Sargassum is still primitive.Here,we investigated the diversity of the culturable epiphytic bacteria and alginate-degrading bacteria from Sargassum samples collected from the coastal seawaters of Shandong Province,China.In total,37 strains belonging to 21 genera in 3 phyla were isolated,including 15 previously unreported genera,of which Vibrio(6/37)and Pseudoalteromonas(5/37)are the dominant genera.Eight strains,mainly Vibrio and Pseudoalteromonas species,were further identified as alginate lyase-excreting strains that can utilize alginate for growth.The extracellular alginolytic activity of the 8 strains was determined,and strains Vibrio sp.C42and Pseudoalteromonas sp.M9 showed the highest activity.These results provide a better understanding of brown algae epiphytes and alginate-degrading bacteria,and are fundamental for further studies on the interactions between brown algae and their epiphytes.

Synergistic effects of alginate oligosaccharide and cyanidin-3-O-glucoside on the amelioration of intestinal barrier function in mice

Emerging evidence shows that dietary oligosaccharides are important prebiotics that can improve intestinal flora,while dietary polyphenols can act directly on intestinal cells.However,information about their synergistic effects on gut health is still limited.In this study,alginate oligosaccharide(AOS)and cyanidin-3-O-glucoside(C3G)were selected as a common marine plant oligosaccharide and terrestrial plant polyphenol,respectively,to study their effects on intestinal health.The results show that,in comparison to their individual applications,the combination of AOS and C3G(mass ratio,3:1)displayed a stronger ability to up-regulate the expression of tight junction proteins,while enhanced intestinal epithelial barrier was also observed and levels of mucin-2 andβ-defensins were simultaneously increased in the intestinal mucus.Interestingly,the secretion of immunoglobulin A and immune-related cytokines were approximately doubled by the AOS+C3G mixture.In addition,the AOS+C3G mixture was found to be more conducive to the positive transformation of intestinal flora,which stimulated the growth of beneficial bacteria Akkermansia,Lachnospiraceae and Feacalibaculum while inhibiting the growth of harmful bacteria Helicobacter and Turicibacter.The data generated herein thus suggests that dietary oligosaccharides and dietary polyphenols may be more beneficial to intestinal health when applied in combination than their individual effects alone.

Alginate and alginate composites for biomedical applications

Alginate is an edible heteropolysaccharide that abundantly available in the brown seaweed and the capsule of bacteria such as Azotobacter sp.and Pseudomonas sp.Owing to alginate gel forming capability,it is widely used in food,textile and paper industries;and to a lesser extent in biomedical applications as biomaterial to promote wound healing and tissue regeneration.This is evident from the rising use of alginate-based dressing for heavily exuding wound and their mass availability in the market nowadays.However,alginate also has limitation.When in contact with physiological environment,alginate could gelate into softer structure,consequently limits its potential in the soft tissue regeneration and becomes inappropriate for the usage related to load bearing body parts.To cater this problem,wide range of materials have been added to alginate structure,producing sturdy composite materials.For instance,the incorporation of adhesive peptide and natural polymer or synthetic polymer to alginate moieties creates an improved composite material,which not only possesses better mechanical properties compared to native alginate,but also grants additional healing capability and promote better tissue regeneration.In addition,drug release kinetic and cell viability can be further improved when alginate composite is used as encapsulating agent.In this review,preparation of alginate and alginate composite in various forms(fibre,bead,hydrogel,and 3D-printed matrices)used for biomedical application is described first,followed by the discussion of latest trend related to alginate composite utilization in wound dressing,drug delivery,and tissue engineering applications.

Origin and evolution of alginate-c5-mannuronan-epimerase gene based on transcriptomic analysis of brown algae

The coding product of alginate-c5-mannuronan-epimerase gene （algG gene） can catalyze the conversion of mannuronate to guluronate and determine the M/G ratio of alginate. Most of the current knowledge about genes involved in the alginate biosynthesis comes from bacterial systems. In this article, based on some algal and bacterial algG genes registered on GenBank and EMBL databases, we predicted 94 algG genes open reading frame （ORF） sequences of brown algae from the 1 000 Plant Transcriptome Sequencing Project （OneKP）. By method of transcriptomic sequence analysis, gene structure and gene localization analysis, multiple sequence alignment and phylogenetic tree construction, we studied the algal algG gene family characteristics, the structure modeling and conserved motifs of AlgG protein, the origin of alginate biosyn-thesis and the variation incidents that might have happened during evolution in algae. Although there are different members in the algal algG gene family, almost all of them harbor the conserved epimerase region. Based on the phylogenetic analysis of algG genes, we proposed that brown algae acquired the alginate bio-synthesis pathway from an ancient bacterium by horizontal gene transfer （HGT）. Afterwards, followed by duplications, chromosome disorder, mutation or recombination during evolution, brown algal algG genes were divided into different types.

Metal cation crosslinking of Ti O_2-alginate hybrid gels

In order to improve the substrate diffusion properties and stability of an immobilized enzyme alginate microgels modified with TiO2 nanoparticles were employed as the enzyme immobilizing support.Ionotropic gelation was applied for the preparation of hybrid gels while Ca2＋ Ce3＋ Ni2＋Cu2＋and Fe3＋were employed as the crosslinkers.Papain was selected as the model enzyme. UV-Vis spectroscopy was employed to investigate the activity of papain to evaluate kinetics and stability.Analysis results show that the highest affinity the lowest Michaelis-Menten constant Km =11.0 mg/mL and the highest stability are obtained when using Cu2＋as the crosslinker.The effect of the mass ratio of TiO2 to papain on the stability and leakage of papain is also investigated and the results show that 10∶1 TiO2∶papain is optimal because the proper use of TiO2 can reduce enzyme leakage and ensure enzyme stability.Preparing Cu/alginate/TiO2 hybrid gels via ionotropic gelation can provide a satisfactory diffusion capability and enzyme stability.