Increases in alginate production and transcription levels of alginate lyase (alyA1) by control of the oxygen transfer rate in Azotobacter vinelandii cultures under diazotrophic conditions

BACKGROUND: Alginates are polysaccharides used in a wide range of industrial applications, with their functional properties depending on their molecular weight. In this study, alginate production and the expression of genes involved in polymerization and depolymerization in batch cultures of Azotobacter vinelandii were evaluated under controlled and noncontrolled oxygen transfer rate (OTR) conditions. RESULTS: Using an oxygen transfer rate (OTR) control system, a constant OTR (20.3 ± 1.3 mmol L 1 h 1 ) was maintained during cell growth and stationary phases. In cultures subjected to a controlled OTR, alginate concentrations were higher (5.5 ± 0.2 g L 1 ) than in cultures under noncontrolled OTR. The molecular weight of alginate decreased from 475 to 325 kDa at the beginning of the growth phase and remained constant until the end of the cultivation period. The expression level of alyA1, which encodes an alginate lyase, was more affected by OTR control than those of other genes involved in alginate biosynthesis. The decrease in alginate molecular weight can be explained by a higher relative expression level of alyA1 under the controlled OTR condition. CONCLUSIONS: This report describes the first time that alginate production and alginate lyase (alyA1) expression levels have been evaluated in A. vinelandii cultures subjected to a controlled OTR. The results show that automatic control of OTR may be a suitable strategy for improving alginate production while maintaining a constant molecular weight.

Genome-Wide Comparison of Carbohydrate-Active Enzymes (CAZymes) Repertoire of Flammulina ononidis

Whole-genome sequencing of Flammulina ononidis, a wood-rotting basidiomycete, was performed to identify genes associated with carbohydrate-active enzymes (CAZymes). A total of 12,586 gene structures with an average length of 2009 bp were predicted by the AUGUSTUS tool from a total 35,524,258 bp length of de novo genome assembly (49.76% GC). Orthologous analysis with other fungal species revealed that 7051 groups contained at least one F. ononidis gene. In addition, 11,252 (89.5%) of 12,586 genes for F. ononidis proteins had orthologs among the Dikarya, and F. ononidis contained 8 species-specific genes, of which 5 genes were paralogous. CAZyme prediction revealed 524 CAZyme genes, including 228 for glycoside hydrolases, 21 for polysaccharide lyases, 87 for glycosyltransferases, 61 for carbohydrate esterases, 87 with auxiliary activities, and 40 for carbohydrate-binding modules in the F. ononidis genome. This genome information including CAZyme repertoire will be useful to understand lignocellulolytic machinery of this white rot fungus F. ononidis.

Research progress of heparinase in the field of medicine / 生物工程学报

Heparinases can produce biologically active oligosaccharides by specifically cleaving the α-(1,4) glycosidic linkages of heparin and heparan sulphate. Heparinases are divided into heparinase and heparanase. Because heparinase is an effective biocatalyst, more and more researchers pay attention to the application of heparinase in medical field in the recent years. Combined with the related research work in our group, the application value of heparinase in the medical field was summarized, such as the determination of the structure of heparin, the preparation of low-molecular-weight heparin and ultra-low-molecular-weight heparin, tumor therapy and as a heparin antagonist. In addition, we summarized the definition, source of heparinase and its application in the medicine field. Heparinases have a great application prospect in the field of medicine.

Pectin lyase overproduction by Penicillium griseoroseum mutants resistant to catabolite repression

Abstract Expression of pectinolytic genes is regulated by catabolic repression limiting the production of pectin lyase (PL) if the natural inducer, pectin, is missing from the growth medium. Here, we report the isolation of Penicillium griseoroseum mutants resistant to 2-deoxy-d-glucose (DG) that show resistance to catabolite repression and overproduce PL. Three spontaneous and nine UV-induced mutants were obtained. Some mutants produced sectors (segments morphologically different) that were also studied. The mutants were analyzed for pectinases production on pectinase-agar plates and five mutants and two sectors showing larger clearing zones than the wild type were selected for quantitative assay. Although PL production higher than the wild type has been found, phenotype instability was observed for most of the mutants and, after transfers to nonselective medium, the DG resistance was no longer present. Only mutants M03 and M04 were stable maintaining the DG-resistance phenotype. When growing for 120 h in liquid medium containing glucose with or without pectin, both mutants showed higher PL production. In the presence of glucose as sole carbon source, the mutant M03 produced 7.8-fold more PL than the wild type. Due its phenotypic stability and PL overproduction, the mutant M03 presents potential for industrial applications.

Culture conditions optimization and high cell density fermentation of recombinant bacteria producing heparinase II from Flavobacterium heparinum / 生物工程学报

Heparinase II (Hep II) from Flavobacterium heparinum is an enzyme that could specifically cleave certain sequence of heparin and heparan sulfate. In this work, fermentation conditions of recombinant heparinase II (His-Hep II) producing bacteria were optimized, including initial induction time, inducer (IPTG) concentration, induction temperature and induction time. The optimum conditions were as follows: cultivating recombinant bacteria to exponential prophase under 37 degrees C, then adding IPTG to a final concentration of 0.3 g/L, finally cultivating recombinant bacteria under 20 degrees C for 10 h. The total crude enzyme activity reached 570 U/L. Based on these results, high cell density fermentation of recombinant bacteria was studied. The final OD600 could reach 98 and the total crude enzyme activity of His-Hep II increased to 9 436 U/L.

Enhancing expression efficiency of alkaline polygalacturonate lyase by constant cell concentration culture of the recombinant Pichia pastoris / 生物工程学报

In order to enhance the alkaline polygalacturonate lyase (PGL) productivity by Pichia pastoris, we developed a constant cell concentration culture strategy by methanol feeding (called as CCCM culture) used in the continuous cultures. We controlled reasonable cell concentrations in the bioprocess by different strategies of methanol feeding. Using this CCCM culture with DCW 75 g/L, we significantly enhanced the PGL productivity (Qv) and the average specific enzyme production rate (Qx) of PGL to 6.11 U/(mL x h) and 81.5 U/(g x h), increased by 42.1% and 191.2% than the fed-batch culture with high cell density, respectively. The final PGL activity was 441.9 U/mL. Moreover, the extracellular protease concentration is 1.9 mg/L and the cell viability is more than 94% after 120 hour induction. The results show that this new strategy is advantageous in reducing proteolytic degradation and enhancing cell viability.

Structural basis of heparan sulfate-specific degradation by heparinase III

Heparinase III (HepIII) is a 73-kDa polysaccharide lyase (PL) that degrades the heparan sulfate (HS) polysaccharides at sulfate-rare regions, which are important co-factors for a vast array of functional distinct proteins including the well-characterized antithrombin and the FGF/FGFR signal transduction system. It functions in cleaving metazoan heparan sulfate (HS) and providing carbon, nitrogen and sulfate sources for host microorganisms. It has long been used to deduce the structure of HS and heparin motifs; however, the structure of its own is unknown. Here we report the crystal structure of the HepIII from Bacteroides thetaiotaomicron at a resolution of 1.6 Å. The overall architecture of HepIII belongs to the (α/α)₅ toroid subclass with an N-terminal toroid-like domain and a C-terminal β-sandwich domain. Analysis of this high-resolution structure allows us to identify a potential HS substrate binding site in a tunnel between the two domains. A tetrasaccharide substrate bound model suggests an elimination mechanism in the HS degradation. Asn260 and His464 neutralize the carboxylic group, whereas Tyr314 serves both as a general base in C-5 proton abstraction, and a general acid in a proton donation to reconstitute the terminal hydroxyl group, respectively. The structure of HepIII and the proposed reaction model provide a molecular basis for its potential practical utilization and the mechanism of its eliminative degradation for HS polysaccarides.

Advances in algae tool enzymes: alginate lyases / 生物工程学报

Marine can be considered as a rather unexplored source of biological material. Production of algal oligosaccharides by using valuable enzymes from marine origin has become an important way to utilize marine resources. As one of algal tool enzymes, the use of alginate lyases has been focused mainly on development and application of alginate oligosaccharides with bioactive function in recent years. In this paper, we reviewed the research of alginate lyases over the past decade in several aspects, including their origin, diversity, substrate specification, mode of action, structure and catalysis mechanism, assay of enzyme activity, enzyme characterization, as well as our own experience on this subject. At the end of the review, the application prospects of alginate lyases are presented.

Advances in microbial production of alkaline polygalacturonate lyase and its application in clean production of textile industry / 生物工程学报

We reviewed the microbial production of alkaline polygalacturonate lyase (PGL) and its application in the clean production of textile industry. Currently PGL is mainly produced by microbial fermentation and Bacillus sp. is an ideal wild strain for PGL production. Microbial PGL production was affected by many factors including the concentration and feeding mode of substrate, cell concentration, agitation speed, aeration rate, pH and temperature. Constructing the recombinant strain provided an effective alternative for PGL production, and the concentration of PGL produced by the recombinant Pichia pastoris reached 1305 U/mL in 10 m3 fermentor. The recombinant Pichia pastoris had the potential to reach the industrial production of PGL. PGL can be applied in bio-scouring process in the pre-treatment of cotton. Compared with the traditional alkaline cooking process, the application of PGL can protect fiber, improve the bio-scouring efficiency, decrease energy consumption and alleviate the environmental pollution. The future research focus will be the molecular directed evolution of PGL to make PGL more suitable for the application of PGL in bio-scouring process to realize the clean production of textile industry.

Effects of mixed carbon sources in cultivation of recombinant Pichia pastoris for polygalacturonate lyase production / 生物工程学报

In order to increase the production and productivity of alkaline polygalacturonate lyase (PGL), we studied the mixed carbon sources feeding strategies during the induction phase by recombinant Pichia pastoris GS 115. Glycerol, sorbitol or lactic acid co-feeding with methanol all enhanced the PGL production. Among all the feeding strategies, the sorbitol co-feeding strategy was most significant. By using this strategy, the PGL activity and productivity reached 1593 U/mL and 16.7 U/(mL-h). Compared to the control, the enhancements of PGL activity and productivity were 84.6% and 45.2% respectively, when we set the sorbitol feeding rate at 3.6 g/(h x L).

Expression of a pectin lyase A gene from Aspergillus niger in Pichia pastoris GS115 / 生物工程学报

In this study, the mature peptide sequence of a pectin lyase gene A was amplified from Aspergillus niger strain EIM-6 by using RT-PCR reverse transcription technique. The cloned gene was then inserted into a Pichia pastoris expression vector pPIC9k to produce the recombinant expression plasmid pPIC9K-pelA. By using electric shocks, we successfully transformed the recombinant pPIC9K-pelA into Pichia pastoris GS115. The activity of the engineered strain reached to 2.3 U/mL after induction with the final concentration of 1.5% methanol. SDS-PAGE analysis revealed that the pPIC9K-pelA transformant had an additional protein band of approximately 38 kD, which was not present in the control. There were no significant differences between the recombinant and native pectin lyase with regard to their hydrolysis activities.

Expression, purification and characterization of a thermostable pectate lyase from Thermotoga maritima / 生物工程学报

The structure gene pelA from Thermotoga maritima MSB8 encoding pectate lyase was amplified and ligated into pHsh, resulting pHsh-pelA. Through structural optimization on pHsh-pelA, the ultimate plasmid, pHsh-pelC, which possessed the most appropriate structure and free energy of mRNA, was obtained. Pectate lyase C (PelC) was obtained after expressing pHsh-pelC in Escherichia coli JM109. The optimum activity of PelC was determined at pH 8.5 at 90 degrees C, with a half-life for almost 2 h at 95 degrees C. PelC was stable at the pH range of 8.2-9.8, and was dependent on Ca2+ for activity and stability. The enzyme kept stable for a long time and possessed a high level of activity at 60 degrees C. The kinetic assay using polygalacturonic acid (PGA) as substrate gave K(m) and V(max) of 0.11 mmol/L and 327 U per mg of protein. SDS-PAGE analysis showed that the molecular mass of the expressed recombinant PelC was about 43 kD, which was exactly the size predicted. The expression vector system of the heat shock plasmid pHsh owned such advantages as high expression level and cheap induction. Moreover, the superior stability of the recombinant enzyme laid the base for large-scale fermentation application.

Acute urticaria caused by the injection of goat-derived hyaluronidase

Hyaluronidase is a goat testicular protein that hydrolyzes hyaluronic acid, a structural component of the intercellular matrix. It is commonly used as a spreading factor to improve the diffusion of drugs, including local anesthetics and chemotherapeutics. We experienced a 55-yr-old female with generalized urticaria that developed within 1 hr after the epidural injection of hyaluronidase. She had a history of allergic rhinitis, and had suffered from post-herpetic neuralgia and a herniated disc for several years. To relieve her pain, she had been given epidural injections consisting of mepivacaine hydrochloride, triamcinolone acetonide, and morphine sulfate biweekly for one year. Hyaluronidase had been administered several times with these drugs before this episode of generalized urticaria. Skin prick testing showed a positive response to 1,500 IU/mL of hyaluronidase extract, as compared to histamine. The patient's serum hyaluronidase-specific IgE level, determined using an enzyme-linked immunosorbent assay (ELISA), was markedly elevated, as compared to unexposed healthy controls. An IgE immunoblot analysis using hyaluronidase extract and the patient's serum showed IgE binding components at 31 and 21 kDa, whereas no corresponding IgE binding component was found in healthy controls. An ELISA inhibition test showed significant, dose-dependent inhibition with the serial addition of hyaluronidase extract. This is the first case of an IgE-medicated allergic reaction to goat (Naemorhedus goral raddenus) hyaluronidase, demonstrated by skin testing and a specific IgE and immunoblot assay.

Acute urticaria caused by the injection of goat-derived hyaluronidase

Hyaluronidase is a goat testicular protein that hydrolyzes hyaluronic acid, a structural component of the intercellular matrix. It is commonly used as a spreading factor to improve the diffusion of drugs, including local anesthetics and chemotherapeutics. We experienced a 55-yr-old female with generalized urticaria that developed within 1 hr after the epidural injection of hyaluronidase. She had a history of allergic rhinitis, and had suffered from post-herpetic neuralgia and a herniated disc for several years. To relieve her pain, she had been given epidural injections consisting of mepivacaine hydrochloride, triamcinolone acetonide, and morphine sulfate biweekly for one year. Hyaluronidase had been administered several times with these drugs before this episode of generalized urticaria. Skin prick testing showed a positive response to 1,500 IU/mL of hyaluronidase extract, as compared to histamine. The patient's serum hyaluronidase-specific IgE level, determined using an enzyme-linked immunosorbent assay (ELISA), was markedly elevated, as compared to unexposed healthy controls. An IgE immunoblot analysis using hyaluronidase extract and the patient's serum showed IgE binding components at 31 and 21 kDa, whereas no corresponding IgE binding component was found in healthy controls. An ELISA inhibition test showed significant, dose-dependent inhibition with the serial addition of hyaluronidase extract. This is the first case of an IgE-medicated allergic reaction to goat (Naemorhedus goral raddenus) hyaluronidase, demonstrated by skin testing and a specific IgE and immunoblot assay.

High-level production of alkaline polygalacturonate lyase in recombinant Pichia pastoris / 生物工程学报

In order to increase the production of alkaline polygalacturonate lyase (PGL) by recombinant Pichia pastoris GS115, the effect of cell and methanol concentration on the PGL production was carefully investigated by single factor experiment. The optimum conditions were listed as follows: the cell concentration 122 g/L, the methanol concentration 20 g/L, and the ratio of methanol and cell concentration 0.16-0.20 g/g (methanol/cell). With the glycerol and methanol feeding strategies, the ratio of methanol and cell concentration could be controlled at the range of 0.171 to 0.195 g/g. And the highest PGL activity (430 u/mL) and highest PGL productivity (4.34 u/mL/h) were achieved.

Hypoxia increases the expression of heparitinase and the invasiveness through the hypoxia inducible factor-1alpha dependent pathway in human ovarian cancer cell line SKOV3 / 中国医学科学院学报

<p><b>OBJECTIVE</b>To investigate the heparitinase (HPA) expression and cell invasiveness in human ovarian cancer cell line SKOV3 during hypoxia, and explore their relationship with hypoxia inducible factor-1alpha (HIF-1alpha).</p><p><b>METHODS</b>SKOV3 cells were incubated with normoxia, hypoxia, and hypoxia plus rapamycin, respectively. SKOV3 cells of hypoxia group were incubated in 5% CO2 + 1% O2. Cells in hypoxia plus rapamycin group were incubated with 10 ng/ml of rapamycin before cultured under hypoxic condition. Cells in each group were collected for analysis after incubated with hypoxia for 12, 24, and 36 hours, respectively. Western blotting and RT-PCR were performed to detect the expressions of HIF-1alpha and HPA. Cell invasiveness was measured by matrigel invasion assay.</p><p><b>RESULTS</b>Western blotting showed that the expression of HIF-1alpha significantly increased compared with normoxic group (P < 0.05). However, hypoxia had no obvious impact on HIF-1alpha mRNA expression. The expressions of HPA protein and mRNA of SKOV3 cells of hypoxia group were significantly higher than normoxic group (P < 0.05). The up-regulation of HPA expression in hypoxic group decreased after the utilization of rapamycin. The cell invasion of hypoxic group was significantly higher than that of normoxic group (P < 0.05); meanwhile, the expression of HPA was positively correlated with the invasiveness of SKOV3 cells (r = 0.9863, P < 0.05).</p><p><b>CONCLUSION</b>Hypoxia may promote the expression of HPA and the invasiveness of SKOV3 cells through the HIF-1alpha pathway, which plays an important role in the pathogenesis of ovarian cancer.</p>

Purification and properties of an extracellular pectin lyase produced by the strain of Penicillium oxalicum in solid-state fermentation.

A pectin lyase (PNL, EC 4.2.2.10) produced extracellularly by the strain of Penicillium oxalicum in solid-state fermentation medium containing deoiled mandarin orange peel meal was purified to apparent homogeneity by a protocol that included ammonium sulfate precipitation, DEAE-Sephadex A-50 and Sephadex G-100 chromatography. The enzyme had molecular mass of 50 kD, as determined by SDS- PAGE and showed optimum pH and temperature at 8.0 and 50 degrees C respectively. It had an isoelectric point (pI) of 5.0 and showed a K(m) of 1.1 mg/ml of citrus pectin. The enzyme was strongly inhibited by Mo4+, Ag+ and Pb2+ and also by polyphenolic compounds, in particular tannic acid.

Expression of pectin lyase 1 from Aspergillus oryzae in Escherichia coli / 生物工程学报

Pectin lyases from Aspergillus oryzae and Aspergillus niger are usually used for the production of traditional fermented foods, but these fungi produce less pectinases under natural conditions. The cDNA coding mature Pell (without signal peptide) was amplified from Aspergillus oryzae by RT-PCR. Pell cDNA was cloned into pET-28a ( + ) expression vector, then was transformed into E. coli Turner (DE3) plac I cells to express Pell with 6-His tag. For improving the efficiency of Pell expression in E. coli, the conditions of expressing the Pell in E. coli were optimized. E. coli Turner (DE3) plac I cells with pET-28a ( + )-pell was first cultivated at 37 degrees C, 220 r/min until OD600 reached about 0.8. Then, cultivation broth was added with 0.05-0.1 mmol/L IPTG and continuously incubated at 15 degrees C, at 170 r/min for 60 h for expressing of Pell. The recombinant expressed Pell activity could reach 400 u/mL medium, which is 4000-fold of Pell produced naturally by A. oryzae and superior than known recombinant amount of pectin lyases expressed in different fungi expression systems.

Activity of glycosidases from freshwater heterotrophic microorganisms on the degradation of extracellular polysaccharide produced by Anabaena spiroides (Cyanobacteria)

A atividade de glicosidases durante a degradação do polissacarídeo extracelular (EPS) produzido por Anabaena spiroides foi detectada e quantificada utilizando-se MUF-substratos (MUF-monossacarídeos). O consumo total do polissacarídeo efetuou-se em duas fases, uma primeira de alta atividade enzimática que rapidamente consumiu 41 per center do polissacarídeo e uma segunda, mais lenta, que consumiu o polissacarídeo restante (59 per center). A mudança de fase coincidiu com a sucessão de uma população de bactérias cocóides por outra de bacilos. A biomassa bacteriana, quantificada por contagens de células, aumentou com a degradação do EPS. As atividades registradas através dos substratos 4-MUF-a-D- e 4-MUF-b-D- glicosídeo foram mais altas quando comparadas aos demais substratos testados que foram: MUF-a-L-ramnopiranosídeo, MUF-b-D-galactosídeo, MUF-a-D-manopiranosídeo, MUF-b-D-fucosídeo, MUF-b-D-manopiranosídeo, MUF-a-L-arabinopiranosídeo, e MUF-b-L-fucosídeo. A fluorescência emitida a partir de cada um dos diferentes MUF-substratos foi, de modo geral, proporcional à concentração dos monossacarídeos correspondentes constituintes do polissacarídeo, um indício da susceptibilidade ao ataque enzimático microbiano do EPS produzido por A. spiroides.

Antibiotics and garlic clove extract--inhibitory agents of cell wall degrading enzymes.

Four antibiotics were tested against Erwinia causing soft rot of onion (Allium cepa var. aggregatum) of which streptomycin sulphate 90% and tetracycline hydrochloride 10% (streptocycline) recorded the maximum inhibition zone of 27.66 mm. In the enzyme studies the maximum inhibition of pectinlyase (PL), polygalacturonase (PG) and protopectinase production was recorded by the same antibiotic. The antibiotics have a significant influence on the production and activity of cell wall degrading enzymes produced by the plant pathogenic microorganisms. Garlic clove extract was equally effective in inhibiting the growth and enzyme production.