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1.
Biotechnol Bioeng ; 120(10): 2969-2976, 2023 10.
Article in English | MEDLINE | ID: mdl-37428609

ABSTRACT

In this work, a novel technique for continuous purification of biologics from a crude feedstock is demonstrated with equipment referred to as Fluidized Bed Adsorption System (FBRAS). The development and validation of such unit operations were performed utilizing lysozyme as a model protein and Relisorb™ SP405/EB as a carrier. The performance of FBRAS to carry out combined clarification and purification was evaluated by capturing of antifungal peptides directly from the lysed broth. The novel technique reduced the number of process unit operations from six to three without having an impact on purity. Overall productivity increased by 250% in comparison to the existing downstream processing routine.


Subject(s)
Proteins , Adsorption
2.
Biotechnol Prog ; 38(2): e3232, 2022 03.
Article in English | MEDLINE | ID: mdl-35037430

ABSTRACT

Ion exchange chromatography is one of the most widely used chromatographic technique for the separation and purification of important biological molecules. Due to its wide applicability in separation processes, a targeted approach is required to suggest the effective binding conditions during ion exchange chromatography. A surface energetics approach was used to study the interaction of proteins to different types of ion exchange chromatographic beads. The basic parameters used in this approach are derived from the contact angle, streaming potential, and zeta potential values. The interaction of few model proteins to different anionic and cationic exchanger, with different backbone chemistry, that is, agarose and methacrylate, was performed. Generally, under binding conditions, it was observed that proteins having negative surface charges showed strong to lose interaction (20 kT for Hannilase to 0.5 kT for IgG) with different anionic exchangers (having different positive surface charges). On the contrary, anionic exchangers showed almost no interaction (0-0.1 kT) with the positively charged proteins. An inverse behavior was observed for the interaction of proteins to cationic exchangers. The outcome from these theoretical calculations can predict the binding behavior of different proteins under real ion exchange chromatographic conditions. This will ultimately propose a better bioprocess design for protein separation.


Subject(s)
Proteins , Adsorption , Anions , Chromatography, Ion Exchange/methods , Proteins/chemistry , Sepharose
3.
J Leukoc Biol ; 112(1): 173-184, 2022 07.
Article in English | MEDLINE | ID: mdl-34811790

ABSTRACT

We previously demonstrated that Bordetella pertussis, the etiologic agent of whooping cough, is able to survive inside human macrophages. The aim of this study was to examine the influence of macrophage polarization in the development of B. pertussis intracellular infections. To this end, primary human monocytes were differentiated into M1, M2a, or M2c macrophages and further infected with B. pertussis. Infected M1 macrophages showed a proinflammatory response evidenced by the production of TNF-α, IL-12p70, and IL-6. Conversely, infection of M2a and M2c macrophages did not induce TNF-α, IL-12p70, nor IL-6 at any time postinfection but showed a significant increase of M2 markers, such as CD206, CD163, and CD209. Interestingly, anti-inflammatory cytokines, like IL-10 and TGF-ß, were induced after infection in the 3 macrophage phenotypes. B. pertussis phagocytosis by M1 macrophages was lower than by M2 phenotypes, which may be ascribed to differences in the expression level of B. pertussis docking molecules on the surface of the different phenotypes. Intracellular bactericidal activity was found to be significantly higher in M1 than in M2a or M2c cells, but live bacteria were still detected within the 3 phenotypes at the late time points after infection. In summary, this study shows that intracellular B. pertussis is able to survive regardless of the macrophage activation program, but its intracellular survival proved higher in M2 compared with the M1 macrophages, being M2c the best candidate to develop into a niche of persistence for B. pertussis.


Subject(s)
Macrophage Activation , Whooping Cough , Bordetella pertussis , Humans , Interleukin-6/metabolism , Macrophages/metabolism , Tumor Necrosis Factor-alpha/metabolism , Whooping Cough/metabolism
4.
Bioresour Bioprocess ; 8(1): 29, 2021 Apr 13.
Article in English | MEDLINE | ID: mdl-38650215

ABSTRACT

In integrated bioprocessing applications, expanded bed adsorption (EBA) chromatography presents an opportunity to harvest biomolecules directly from the crude feedstock. However, unfavorable biomass interactions with adsorbent usually leads to fouling, which reduces its protein binding capacity as it alters column hydrodynamics and binding site availability. In this work, a detailed study on biomass adhesion behavior of four different industrially relevant microorganisms on 26 different, most commonly occurring adsorbent surfaces with varying degrees of surface energy and surface charge has been conducted. The results showed the derivation of a relative "stickiness" factor for every microorganism, which further classifies each organism based on their general degree of adhesion to surfaces with respect to one another. The obtained results can help to better understand the effect of biomass homogenization on biomass-adsorbent interactions in EBA. The data of surface energy and charge for the surfaces investigated in this work can be used to calculate the stickiness factor of other microorganisms of interest and may assist in the development of novel adsorbent materials for EBA chromatography.

5.
Food Res Int ; 132: 109094, 2020 06.
Article in English | MEDLINE | ID: mdl-32331629

ABSTRACT

Fungi are known to modify the properties of lignocellulosic materials during solid-state fermentation (SSF). In this study, agricultural side-streams (sunflower seed hulls, rice husks and rice straw) were used as substrates for SSF with dikaryotic and monokaryotic strains of Pleurotus sapidus. The phenolic profiles of the mentioned substrates were characterized by LC-DAD/ESI-MSn pre- and post- fermentation. Moreover, antioxidant, cytotoxic and antimicrobial activities were screened against oxidizable cellular substrates, tumour and primary cell lines, and different bacteria and fungi, respectively. The concentration of phenolic compounds in the crop side-streams was reduced after fermentation with both strains of the fungus. The fermented extracts also displayed lower antioxidant and cytotoxic activities and had no hepatotoxicity. The antimicrobial activity depended upon the crop side-stream and/or SSF conditions. These results indicate that P. sapidus represent a good candidate to modify the phenolic fraction presents in crop side-streams with a consequent decrease in its bioactivities. However, the SSF with P. sapidus strains play an interesting role in the detoxification of plant materials which can be used for different applications according to the "reduce - reuse - recycle" concept contributing with the sustainable land use and circular economy.


Subject(s)
Fermentation , Helianthus/metabolism , Oryza/metabolism , Phenols/analysis , Pleurotus/metabolism , Agriculture , Anti-Infective Agents , Antioxidants/analysis , Biomass , Biotransformation , Culture Media/chemistry , Waste Products
6.
Bioresour Technol ; 289: 121692, 2019 Oct.
Article in English | MEDLINE | ID: mdl-31265963

ABSTRACT

Pleurotus sapidus monokaryotic strains (Mk) were screened as a novel source of mycelia to valorize rice straw (RS), rice husks (RH) and sunflower seed hulls (SSH) into value-added products through solid-state fermentation (SSF). P. sapidus Dk3174 basidiospores were cultured in the presence of Remazol Brillant Blue R for strain selection, revealing the ligninolytic ability of emerging colonies. Further screening demonstrated the intraspecific variability in dye degradation and enzyme production of 63 strains. Growth rate, biomass and enzyme production in plates containing RS, RH or SSH pointed at MkP6 as a suitable strain for pilot-scale SSF. MkP6 presented a similar laccase profile as the parental Dk3174, being greater in pasteurized substrates (300-1200 U/Kg) than in sterilized substrates (30-250 U/Kg). Peroxidase represented 25% of the total ligninolytic activity measured. The SSH fermented biomass with MkP6 obtained good yields of nanocellulose (67%) and the saccharide release for ethanol production increased by 3-4 times.


Subject(s)
Fermentation , Helianthus/metabolism , Oryza/metabolism , Pleurotus/metabolism , Biomass , Laccase/metabolism , Peroxidase/metabolism , Peroxidases/metabolism
7.
Protein Expr Purif ; 155: 27-34, 2019 03.
Article in English | MEDLINE | ID: mdl-30445097

ABSTRACT

In antibody purification processes, affinity chromatography has been used with Staphylococcus aureus protein A (SpA) as the main ligand. In this work, we present a novel Staphylococcal Protein A (AviPure thereafter), a synthetic ligand analogue based on native SpA B domain, with a molecular weight of approximately 14 kDa. The binding affinity of mAbs to AviPure was evaluated using Surface Plasmon Resonance (SPR) and affinity chromatography methods. The equilibrium dissociation constant (KD) between the AviPure and mAbs was systematically measured using 1:1 (Langmuir) model and found to be 4.7 × 10-8 M, with constant of dissociation at kd ≤ 1.0 × 10-3 s-1 and ka being 3.1 × 104 M-1 s-1. When immobilized on Sepharose, the AviPure ligand density was 429 nmol/g moist weight resin and was able to effectively bind immunoglobulin and Fc fragment samples with higher affinity and the most effective flow rate when using ligand - Sepharose beads was at 75 cm/h giving the dynamic binding capacity of 53 mg/mL and 91% recovery of IgG. Suitable ligands used in affinity purification should have a KD ≤ 10-6 M and a dissociation rate (ka) averaging 10-3 M-1 s-1 with the kd ranging between 103 - 108 M-1. Therefore, the AviPure ligand can be used as an alternative to the standard protein A ligand in the purification of mAbs and Fc-fused proteins.


Subject(s)
Chromatography, Affinity/methods , Immunoglobulin Fc Fragments/isolation & purification , Immunoglobulin G/isolation & purification , Staphylococcal Protein A/chemistry , Humans , Immobilized Proteins/chemistry , Ligands , Protein Binding , Recombinant Fusion Proteins/isolation & purification , Staphylococcus aureus/chemistry
8.
Microbiol Immunol ; 61(10): 407-415, 2017 Oct.
Article in English | MEDLINE | ID: mdl-28857261

ABSTRACT

Whooping cough, which is caused by Bordetella pertussis and B. parapertussis, is a reemerging disease. New protective antigens are needed to improve the efficacy of current vaccines against both species. Using proteomic tools, it was here found that B. parapertussis expresses a homolog of AfuA, a previously reported new vaccine candidate against B. pertussis. It was found that this homolog, named AfuABpp , is expressed during B. parapertussis infection, exposed on the surface of the bacteria and recognized by specific antibodies induced by the recombinant AfuA cloned from B. pertussis (rAfuA). Importantly, the presence of the O-antigen, a molecule that has been found to shield surface antigens on B. parapertussis, showed no influence on antibody recognition of AfuABpp on the bacterial surface. The present study further showed that antibodies induced by immunization with the recombinant protein were able to opsonize B. parapertussis and promote bacterial uptake by neutrophils. Finally, it was shown that this antigen confers protection against B. parapertussis infection in a mouse model. Altogether, these results indicate that AfuA is a good vaccine candidate for acellular vaccines protective against both causative agents of whooping cough.


Subject(s)
Antigens, Bacterial/genetics , Antigens, Bacterial/immunology , Bacterial Outer Membrane Proteins/genetics , Bacterial Outer Membrane Proteins/immunology , Bordetella Infections/prevention & control , Bordetella parapertussis/drug effects , Bordetella pertussis/genetics , Pertussis Vaccine/immunology , Recombinant Proteins/genetics , Recombinant Proteins/immunology , Animals , Antibodies, Bacterial/immunology , Bacterial Proteins/genetics , Bacterial Proteins/immunology , Bordetella Infections/immunology , Bordetella parapertussis/immunology , Bordetella parapertussis/pathogenicity , Bordetella pertussis/drug effects , Bordetella pertussis/immunology , Bordetella pertussis/metabolism , Disease Models, Animal , Female , Immunization , Mice , Mice, Inbred BALB C , Neutrophils/immunology , O Antigens/immunology , Proteomics , Vaccination , Vaccines, Acellular/genetics , Vaccines, Acellular/immunology , Whooping Cough/microbiology
9.
Electrophoresis ; 38(22-23): 2914-2921, 2017 11.
Article in English | MEDLINE | ID: mdl-28833255

ABSTRACT

Common limitations of Protein A affinity chromatography include high adsorbent costs, ligand instability and possible ligand leakage. In this study, a short peptide with affinity for IgG was synthesized chemically and subsequently immobilized on a megaporous support. The support was prepared utilising the cryogel technique while the peptide-ligand was covalently immobilised via thiol-epoxy click chemistry. The cryogel support was chemically grafted to increase the number of reaction sites. This adsorbent was designated as "MP-Pep". Adsorption isotherms were employed to evaluate protein binding capacity. A maximum static binding capacity within the range of 30-60 mg/mL was observed for T hIgG. This parameter compares well with other commercial and non-commercial adsorbents, as reported in the literature. As a control material, a Protein A grafted megaporous cryogel was synthesized. Dynamic binding capacity values were obtained by breakthrough analysis. The peptide cryogel showed a dynamic capacity value 9.0 mg/mL in comparison to 9.7 mg/mL in the case of the Protein A based adsorbent. The ratio of dynamic binding capacity to static binding capacity was 20%, indicating suboptimal product capture. However, the advantage of MP-Pep lies in its cost-effective preparations while maintaining a reasonable binding capacity for the targeted product. The presence of cooperative effects during protein binding could also represent an advantage during the processing of a feedstock containing a product in high concentration.


Subject(s)
Chromatography, Affinity/methods , Immunoglobulin G/isolation & purification , Peptides/metabolism , Adsorption , Humans , Immunoglobulin G/chemistry , Immunoglobulin G/metabolism , Ligands , Peptides/chemistry , Porosity
10.
AMB Express ; 7(1): 158, 2017 Dec.
Article in English | MEDLINE | ID: mdl-28759988

ABSTRACT

The successful industrial production of ethanol and fine chemicals requires the development of new biocatalytic reactors and support materials to achieve economically viable processes. In this work, a Stirred-Catalytic-Basket-BioReactor using various immobilizing foams as support material and compared to free cells were used, focusing mainly on; (i) effect of mass-transfer on cells physiology and (ii) ethanol productivity. The performance of the reactor was further evaluated by ethanol volumetric productivity, yield and time for process completion and it was found that the variation of ethanol production and diffusion of the substrate in fermentation process are co-related with the stirrer speed and initial glucose concentration. It was also observed that the time difference for glucose consumption between free and immobilized cells (alginate and sponges) tends to increase by increasing the glucose concentration in the medium. We found that at higher stirrer speed (500 rpm) when using higher glucose concentration (200 g/l), ethanol volumetric productivity increased significantly in the sponge (85 g/l) as compared to alginate beads (79 g/l) and free cells (60 g/l). From the data obtained, it can be concluded that sponges are the best support material for attaining higher ethanol productivity. A stirred catalytic basket bioreactor with yeast cells immobilized in polyethylene sponge gives higher ethanol production at a higher glucose consumption rate, and this productivity is due to higher mixing efficiency and reduced external as well as internal mass transfer limitations. The potentials of the reactor rank it as a remarkable ethanol/fine-chemical production approach that needs further investigations.

11.
AMB Express ; 5(1): 70, 2015 Dec.
Article in English | MEDLINE | ID: mdl-26556030

ABSTRACT

The major platform for high level recombinant protein production is based on genetically modified microorganisms like Escherichia coli (E. coli) due to its short dividing time, ability to use inexpensive substrates and additionally, its genetics is comparatively simple, well characterized and can be manipulated easily. Here, we investigated the possibilities of finding the best media for high cell density fermentation, by analyzing different media samples, focusing on improving fermentation techniques and recombinant protein production. Initial fermentation of E. coli BL21 DE3:pAV01 in baffled flasks showed that high cell density was achieved when using complex media, Luria-Bertani (LB) and Terrific medium broth (TB) (10 and 14 g/L wet weight, respectively), as compared to mineral media M9, modified minimal medium (MMM) and Riesenberg mineral medium (RM) (7, 8 and 7 g/L, respectively). However, in fed-batch fermentation processes when using MMM after 25 h cultivation, it was possible to yield an optical density (OD600) of 139 corresponding to 172 g/L of wet biomass was produced in a 30 L TV Techfors-S Infors HT fermenter, with a computer controlled nutrient supply (glucose as a carbon source) delivery system, indicating nearly 1.5 times that obtained from TB. Upon purification, a total of 1.65 mg/g of protein per gram cell biomass was obtained and the purified AviPure showed affinity for immunoglobulin. High cell density fed batch fermentation was achieved by selecting the best media and growth conditions, by utilizing a number of fermentation parameters like media, fermentation conditions, chemical concentrations, pO2 level, stirrer speed, pH level and feed media addition. It is possible to reach cell densities higher than shake flasks and stirred tank reactors with the improved oxygen transfer rate and feed.

12.
AMB Express ; 5(1): 138, 2015 Dec.
Article in English | MEDLINE | ID: mdl-26272478

ABSTRACT

The influence of internal mass transfer on productivity as well as the performance of packed bed bioreactor was determined by varying a number of parameters; chitosan coating, flow rate, glucose concentration and particle size. Saccharomyces cerevisiae cells were immobilized in chitosan and non-chitosan coated alginate beads to demonstrate the effect on particle side mass transfer on substrate consumption time, lag phase and ethanol production. The results indicate that chitosan coating, beads size, glucose concentration and flow rate have a significant effect on lag phase duration. The duration of lag phase for different size of beads (0.8, 2 and 4 mm) decreases by increasing flow rate and by decreasing the size of beads. Moreover, longer lag phase were found at higher glucose medium concentration and also with chitosan coated beads. It was observed that by increasing flow rates; lag phase and glucose consumption time decreased. The reason is due to the reduction of external (fluid side) mass transfer as a result of increase in flow rate as glucose is easily transported to the surface of the beads. Varying the size of beads is an additional factor: as it reduces the internal (particle side) mass transfer by reducing the size of beads. The reason behind this is the distance for reactants to reach active site of catalyst (cells) and the thickness of fluid created layer around alginate beads is reduced. The optimum combination of parameters consisting of smaller beads size (0.8 mm), higher flow rate of 90 ml/min and glucose concentration of 10 g/l were found to be the maximum condition for ethanol production.

13.
Bioprocess Biosyst Eng ; 38(11): 2117-28, 2015 Nov.
Article in English | MEDLINE | ID: mdl-26256022

ABSTRACT

The application of cellulases in saccharification processes is restricted by its production cost. Consequently, new fungal strains able to elaborate higher cellulases titers and with special activity profiles are required to make the process economical. The aim of this investigation was to find a promising wild-type Trichoderma strain for cellulases production. The Trichoderma reesei strain 938 (CBS 836.91) was selected among twenty strains on the basis of cellulase-agar-plate screening. Evaluation of the selected strain on six solid substrates indicated the highest activities to be obtained from wheat bran. Statistical analyses of the experimental design indicated a significant effect of pH and moisture on the generation of endoglucanase (EGA) and filter-paper (FPA) activity. Furthermore, a central-composite design-based optimization revealed that pH values between 6.4 and 6.6 and moisture from 74 to 94% were optimal for cellulases production. Under these conditions, 8-10 IU gds(-1) of FPA and 15.6-17.8 IU gds(-1) of EGA were obtained. In addition, cultivation in a rotating-drum reactor under optimal conditions gave 8.2 IU gds(-1) FPA and 13.5 IU gds(-1) EGA. Biochemical characterization of T. reesei 938 cellulases indicated a substantially higher resistance to 4 mM Fe(+2) and a slightly greater tolerance to alkaline pH in comparison to Celluclast(®). These results suggest that T. reesei 938 could be a promising candidate for improved cellulases production through direct-evolution strategies.


Subject(s)
Cellulases/biosynthesis , Dietary Fiber/metabolism , Fungal Proteins/biosynthesis , Trichoderma/growth & development
14.
Appl Microbiol Biotechnol ; 99(22): 9699-708, 2015 Nov.
Article in English | MEDLINE | ID: mdl-26224427

ABSTRACT

The biotechnological value of Aspergillus sojae ATCC 20235 (A. sojae) for production of pectinases in solid-state fermentation (SSF) has been demonstrated recently. However, a common drawback of fungal solid-state cultures is the poor diffusion of oxygen into the fungi that limits its growth and biological productivity. The bacterial Vitreoscilla hemoglobin (VHb) has favored the metabolism and productivities of various bacterial and yeast strains besides alleviating hypoxic conditions of its native host, but the use of VHb in filamentous fungi still remains poor explored. Based on the known effects of VHb, this study assessed its applicability to improve A. sojae performance in SSF. The VHb gene (vgb) under control of the constitutive Aspergillus nidulants gpdA promoter was introduced into the genome of A. sojae by Agrobacterium-mediated transformation. Successful fungal transformants were identified by fluorescence microscopy and polymerase chain reaction (PCR) analyses. In solid-state cultures, the content of protease, exo-polygalacturonase (exo-PG), and exo-polymethylgalacturonase (exo-PMG) of the transformed fungus (A. sojae vgb+) improved were 26, 60, and 44 % higher, respectively, in comparison to its parental strain (A. sojae wt). Similarly, biomass content was also 1.3 times higher in the transformant strain. No significant difference was observed in endo-polygalacturonase (endo-PG) content between both fungal strains, suggesting dissimilar effects of VHb towards different enzymatic productions. Overall, our results show that biomass, protease, and exo-pectinase content of A. sojae in SSF can be improved by transformation with VHb.


Subject(s)
Aspergillus/growth & development , Aspergillus/metabolism , Bacterial Proteins/metabolism , Culture Media , Polygalacturonase/metabolism , Truncated Hemoglobins/metabolism , Aspergillus/enzymology , Aspergillus/genetics , Bacterial Proteins/genetics , Biomass , Oxygen/metabolism , Polygalacturonase/genetics , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Truncated Hemoglobins/genetics
15.
AMB Express ; 5: 25, 2015.
Article in English | MEDLINE | ID: mdl-25977875

ABSTRACT

The influence of mass transfer on productivity as well as the performance of packed bed bioreactor was determined by varying a number of parameters; flow rate, glucose concentration and polymers (chitosan). Saccharomyces cerevisiae cells were immobilized in chitosan and non-chitosan coated alginate beads to demonstrate the effect on external mass transfer by substrate consumption time, lag phase and ethanol production. The results indicate that coating has a significant effect on the lag phase duration, being 30-40 min higher than non-coated beads. After lag phase, no significant change was observed in both types of beads on consumption of glucose with the same flow rate. It was observed that by increasing flow rates; lag phase and glucose consumption time decreased. The reason is due to the reduction of external mass transfer as a result of increase in flow rate as glucose is easily transported to and from the beads surface by diffusion. It is observed that chitosan acts as barrier for transfer of substrate and products, in and out of beads, at initial time of fermentation as it shows longer lag phase for chitosan coated beads than non-coated. Glucose consumption at low flow rate was lower as compared to higher flow rates. The optimum combination of parameters consisting of higher flow rates 30-90 ml/min and between 10 and 20 g/l of glucose was found for maximum production of ethanol.

16.
Methods Mol Biol ; 1286: 201-12, 2015.
Article in English | MEDLINE | ID: mdl-25749956

ABSTRACT

Immobilized metal-ion affinity chromatography (IMAC) has been developed for the rapid isolation and purification of recombinant proteins. In this chapter, megaporous cryogels were synthesized having metal-ion affinity functionality, and their adsorptive properties were investigated. These cryogels have large pore sizes ranging from 10 to 100 µm with corresponding porosities between 80 and 90%. The synthesized IMAC-cryogel had a total ligand density of 770 µmol/g. Twelve milligram of a His6-tagged protein (NAD(P)H-dependent 2-cyclohexen-1-one-reductase) can be purified from a crude cell extract per gram of IMAC-cryogels. The protein binding capacity is increased with higher degrees of grafting, although a slight decrease in column efficiency may result. This chapter provides methodologies for a rapid single-step purification of recombinant His6-tagged proteins from crude cell extracts using IMAC-cryogels.


Subject(s)
Chromatography, Affinity/methods , Copper/chemistry , Cryogels/chemistry , Histidine/chemistry , Oligopeptides/chemistry , Recombinant Proteins/chemistry , Recombinant Proteins/isolation & purification , Electrophoresis, Polyacrylamide Gel , Imidazoles/chemistry , Ligands , Porosity
17.
J Mol Recognit ; 28(3): 191-200, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25663265

ABSTRACT

The multifunctional bone sialoprotein/apatite (AP) self-assembled systems in the mineralized tissues show a pathway for the noncovalent immobilization of ligands on the AP chromatographic matrix. A model approach is presented here regarding the physical immobilization of ligands on the ceramic fluorapatite (CFT) matrix for the purification of human Immunoglobulin G (hIgG). The peptide pIC, HWRGWV-KPRSVSG, composed of a hIgG-specific peptide, HWRGWV (pLI), and a CFT-specific peptide, KPRSVSG (pTC), was synthesized and subjected to physicochemical characterization. A circular dichroism study showed that pIC possesses a flexible structural feature, which is significant in terms of its multifunctional activities. With the current approach, hIgG will be retained selectively by the self-assembled pIC/CFT column, while other biomolecules will pass through the column without being interacted. Therefore, the chromatographic conditions that are the key factors for the successful implementation of this technique were optimized as a function of the composition and pH of the mobile phase. Here, 115 mM sodium chloride (NaCl) in 20 mM sodium phosphate, pH 7.4, was used as the binding buffer, and the elution was performed with 225 mM NaCl in 20 mM sodium phosphate containing 0.3% w/v sodium acetate at pH 6. The binding capacity of the pIC/CFT column was 21.5 mg hIgG/ml matrix with a ligand density of 18.8 µmol/ml, and the binding capacity of the column increased with the increment of ligand density. Afterward, the applicability of a spacer arm between pLI and pTC was also verified. The hIgG-binding capacity of the column decreased with the increment in size of the spacer. In conclusion, the peptide-mediated self-assembled biomimetic system can be used as an alternative to the chemical immobilization of ligands in order to prevent unwanted consequences that result from some of the conventional ligand coupling chemistry.


Subject(s)
Apatites/chemistry , Chromatography, Affinity/methods , Immunoglobulin G/isolation & purification , Peptides/chemical synthesis , Ceramics , Circular Dichroism , Humans , Hydrogen-Ion Concentration , Immunoglobulin G/chemistry , Peptides/chemistry
18.
J Sci Food Agric ; 95(7): 1554-61, 2015 May.
Article in English | MEDLINE | ID: mdl-25103563

ABSTRACT

BACKGROUND: In the food industry, the use of pectinase preparations with high pectin esterase (PE) activity leads to the release of methanol, which is strictly regulated in food products. Herein, a pectin-degrading enzyme (PDE) complex exhibiting low PE activity of three Aspergillus sojae ATCC 20235 mutants (M3, DH56 and Guserbiot 2.230) was investigated. Production of exo-/endo-polygalacturonase (PG), exo-polymethylgalacturonase (PMG) and pectin lyase (PL) by mutant M3 and A. sojae using two different carbon sources was evaluated in solid-state fermentation. Finally, experimental preparations obtained from the mutants and commercial pectinases standardized to the same potency were screened for PDEs. RESULTS: Mutant M3 grown on sugar beet was found to be the best producer of exo-PG, endo-PG, exo-PMG and PL, with maximum yields of 1111, 449, 130 and 123 U g(-1), respectively. All experimental preparations exhibited low PE activity, at least 21.5 times less than commercial pectinases, and higher endo-PG (40 U mL(-1)). CONCLUSION: Mutant M3 was the best PDE producer using sugar beet. Mutant strains presented a PDE complex featuring high endo-PG and very low PE activities. This novel complex with low de-esterifying activity can be exploited in the food industry to degrade pectin without releasing methanol.


Subject(s)
Aspergillus niger/enzymology , Beta vulgaris , Fermentation , Multienzyme Complexes/metabolism , Mutation , Pectins/metabolism , Polygalacturonase/metabolism , Aspergillus niger/genetics , Aspergillus niger/growth & development , Culture Media , Esterases/metabolism , Esterification , Humans , Lyases/biosynthesis , Lyases/metabolism , Methanol/metabolism
19.
J Mol Recognit ; 27(11): 659-68, 2014 Nov.
Article in English | MEDLINE | ID: mdl-25277090

ABSTRACT

Fusion of peptide-based tags to recombinant proteins is currently one of the most used tools for protein production. Also, immobilized metal ion affinity chromatography (IMAC) has a huge application in protein purification, especially in research labs. The combination of expression systems of recombinant tagged proteins with this robust chromatographic system has become an efficient and rapid tool to produce milligram-range amounts of proteins. IMAC-Ni(II) columns have become the natural partners of 6xHis-tagged proteins. The Ni(II) ion is considered as the best compromise of selectivity and affinity for purification of a recombinant His-tagged protein. The palladium(II) ion is also able to bind to side chains of amino acids and form ternary complexes with iminodiacetic acid and free amino acids and other sulfur-containing molecules. In this work, we evaluated two different cysteine- and histidine-containing six amino acid tags linked to the N-terminal group of green fluorescent protein (GFP) and studied the adsorption and elution conditions using novel eluents. Both cysteine-containing tagged GFPs were able to bind to IMAC-Pd(II) matrices and eluted successfully using a low concentration of thiourea solution. The IMAC-Ni(II) system reaches less than 20% recovery of the cysteine-containing tagged GFP from a crude homogenate of recombinant Escherichia coli, meanwhile the IMAC-Pd(II) yields a recovery of 45% with a purification factor of 13.


Subject(s)
Chromatography, Affinity/methods , Cysteine/chemistry , Green Fluorescent Proteins/isolation & purification , Histidine/chemistry , Palladium/chemistry , Peptide Fragments/chemistry , Recombinant Proteins/isolation & purification , Cysteine/metabolism , Escherichia coli , Green Fluorescent Proteins/chemistry , Green Fluorescent Proteins/metabolism , Histidine/metabolism , Humans , Palladium/metabolism , Peptide Fragments/metabolism , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism
20.
BMC Microbiol ; 14: 247, 2014 Sep 25.
Article in English | MEDLINE | ID: mdl-25253558

ABSTRACT

BACKGROUND: Aspergillus sojae has been an important filamentous fungus in Biotechnology due to its use in diverse fermentative processes for the production of various food products. Furthermore, this fungus is a common expression system for the production of enzymes and other metabolites. The availability of molecular genetic tools to explore its biology is thus of big interest. In this study, an Agrobacterium tumefaciens-mediated transformation (ATMT) system for A. sojae was developed and its applicability evaluated. RESULTS: The donor plasmid named pRM-eGFP was constructed for ATMT of A. sojae. This plasmid contains the ble and egfp genes in its transfer DNA element (T-DNA) to confer phleomycin resistance and express the enhanced green fluorescent protein (EGFP) in A. sojae, respectively. Agrobacterium tumefaciens (LBA4404) harboring the donor plasmid and A. sojae (ATCC 20235) were co-cultured under diverse conditions to achieve ATMT. The maximum number of transformed fungi was obtained after three days of co-culturing at 28°C, and selection with 50 µg/ml phleomycin. Polymerase chain reaction (PCR), fluorescence microscopy and Western Blot analysis for EGFP expression confirmed successful genomic integration of the T-DNA element in A. sojae. The T-DNA was mitotically stable in approximately 40% of the fungal transformants after four generations of sub-culturing under phleomycin pressure. CONCLUSION: We successfully established a new ATMT protocol for A. sojae. This transformation system should enable further protein expression studies on this filamentous fungus.


Subject(s)
Agrobacterium tumefaciens/genetics , Aspergillus/genetics , Transformation, Genetic/genetics , DNA, Bacterial/genetics , Genetic Vectors/genetics , Green Fluorescent Proteins/genetics , Plasmids/genetics
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