Purification and characterization of a novel anticoagulant and fibrinolytic enzyme produced by endophytic bacterium Paenibacillus polymyxa EJS-3

INTRODUCTION

Endophytes may become a new source of thrombolytic agents for thrombosis treatment.

MATERIALS AND METHODS

A novel fibrinolytic enzyme from Paenibacillus polymyxa EJS-3 (PPFE-I) was purified with ammonium sulfate precipitation, hydrophobic chromatography, ion exchange and gel filtration chromatography. The characterization of the enzyme was investigated by means of fibrinolysis plate, hydrolysis of fibrinogen and anticoagulant effect in vitro.

RESULTS

The fibrinolytic enzyme is purified to homogeneity with a purification of 14.5 fold and a recovery of 3.3%. The enzyme was shown to have a molecular mass of 63.3kDa by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The optimum temperature and pH value were 37°C and 7.5, respectively. Results from the fibrinolysis pattern showed that the enzyme rapidly hydrolyzed the Aα-chain of fibrinogen, followed by the Bβ-chains. It also hydrolyzed the γ-chains, but more slowly. It was activated by metal ions such as Zn(2+), Mg(2+), and Fe(2+), but inhibited by Ca(2+) and Cu(2+). Furthermore, PPFE-I activity was inhibited strongly by PMSF, and it was found to exhibit a higher specificity for the synthetic substrate N-succinyl-Ala-Ala-Pro-Phe-pNA for chymotrypsin, indicating that the enzyme is a chymotrypsin-like serine protease. Additionly, PPFE-I showed a significant anticoagulant effect in vitro.

CONCLUSION

The fibrinolytic enzyme PPFE-I from endophytic bacterium Paenibacillu polymyxa EJS-3 exhibits a profound fibrinolytic activity.

A simple method for the simultaneous decoloration and deproteinization of crude levan extract from Paenibacillus polymyxa EJS-3 by macroporous resin

A simple method for the simultaneous decoloration and deproteinization of crude levan extract from the endophytic bacterium Paenibacillus polymyxa EJS-3 was developed through static and dynamic adsorption tests of macroporous resins. S-8 resin demonstrated the highest decoloration and deproteinization ratios among various resins tested. Under optimized static adsorption conditions (pH 6.0, 35 degrees C and adsorption time of 70 min), the ratios of decoloration, deproteinization and polysaccharide recovery for S-8 resin were 76.8%, 78.9% and 69.0%, respectively. Under optimized dynamic adsorption condition (flow rate of 2 BV/h, 160 ml of 2.5mg/ml crude levan extract), higher ratios of decoloration, deproteinization and polysaccharide recovery for S-8 resin (84.6%, 91.7% and 81.3%, respectively) were observed. The method developed will provide a potential approach for large-scale production of levan from P.polymyxa EJS-3.

[Fusion expression of fibrinolytic enzyme gene PPFE-I from endophytic Paenibacillus polymyxa in Escherichia coli and activity analysis]

With the genomic DNA of strain EJS-3 as the template, we amplified the gene of fibrinolytic enzyme from Paenibacillus polymyxa (PPFE-I) by PCR. We purified the PCR product and ligated it into pMD19-T. After DNA sequencing, we cloned the PPFE-I gene into expression vector pET-DsbA and transformed it into Escherichia coli BL21(DE3). Upon induction of IPTG, we found that the activity of recombinant fibrinolytic enzyme fused with DsbA expressed in Escherichia coli was 228 IU/mL. SDS-PAGE analysis showed that the recombinant enzyme was soluble and accounted for about 18.4% of total cell protein. Western blotting demonstrated that the recombinant protein was DsbA-PPFE-I. We purified the recombinant enzyme by Ni affinity chromatography, thrombin digestion and sephadex G-100 gel-filtration, and identified the molecular weight of purified product to be 66.3 kDa with MALDI-TOF mass spectrometry. The purified enzyme exhibited distinct fibrinolytic activity on fibrin plate.

[Cloning and expression of non-position-specific lipase gene from Proteus vulgaris]

OBJECTIVE

To produce Proteus vulgaris lipase (PVL) in large quantities, we cloned and expressed the lipase gene in Escherichia coli.

METHODS

We cloned PVL gene by PCR method and then inserted the open reading frame of PVL gene into pET-DsbA and pMBP-P vectors. PVL gene was expressed in E. coli with the introduction of isopropyl beta-D-1-thiogalactopyranoside (IPTG). We also studied the optimal culture conditions, including the concentrations of glucose, IPTG and ampicillin, induction temperature, and pH value of the medium. The characteristics of recombinant lipase were examined after affinitive purification by His-chelating affinity chromatography.

RESULTS

The open reading frame of PVL gene consisted of 864 base pairs, encoding a protein of 287 amino acids. The sequence was deposited to GenBank with the accession number FJ643627. The gene was expressed in E. coli and active lipase was obtained from E. coli BL21 cells by the induction of IPTG, and the lipase production reached 192. 2 U/mL in BL21 [pET-PVL] after culture for 15 h at 15 degrees C. The maximum production was obtained by culturing BL21 cells in LB medium (pH 8.5) with 15 mg/mL glucose and 200 mg/L ampicillin, as well as adding 100 mg/L IPTG at OD600 of 1.2. A single protein band of 31 kDa was displayed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) after affinitive purification. The properties of lipase expressed in E. coli were similar to the native one, which could hydrolyze all three esters of triglyceride.

CONCLUSION

We have succeeded in over-expressing the lipase gene from P. vulgaris in E. coli, and this research has laid a foundation for improvement and industrial application of this lipase.

Incidence, management and mortality of acute hypoxemic respiratory failure and acute respiratory distress syndrome from a prospective study of Chinese paediatric intensive care network

AIM

To investigate the incidence, clinical management, mortality and its risk factors, major outcome and costs of acute hypoxemic respiratory failure (AHRF) and acute respiratory distress syndrome (ARDS) in a Chinese network of 26 paediatric intensive care unit (PICU).

METHODS

In a consecutive 12-month period, AHRF and ARDS were identified and followed up for 90 days or until death or discharge.

RESULTS

From a total of 11 521 critically ill patients, 461 AHRF were identified in which 306 developed ARDS (66.4%), resulting in incidences of 4% and 2.7%, respectively, with pneumonia (75.1%) and sepsis (14.7%) as main underlying diseases and 83% were 5 years and 1 month-old. In-hospital mortality of AHRF was 41.6% (44.8% for ARDS), accounted for 15.5% of all PICU deaths. For those of pneumonia or sepsis with AHRF and ARDS, mortality and its relative risk were significantly higher than those without. Relatively lower tidal volume and total fluid balance, adequate upper limit of PaCO(2) in the early PICU days, and family affordability, tended to result in better outcome.

CONCLUSION

In this prospective study, AHRF had high possibilities to develop ARDS and death risk, as impacted by ventilation settings and fluid intake in the early treatment, as well as socioeconomic factors, which should be considered for implementation of standard of care in respiratory therapy.

Enhancement of surfactin production of Bacillus subtilis fmbR by replacement of the native promoter with the Pspac promoter

Bacillus subtilis fmbR-1 was obtained from wild-type B. subtilis fmbR by replacement of the native promoter of the surfactin operon with the inducible promoter Pspac. The recombinant B. subtilis fmbR-1 produced more antibacterial substances than the wild-type strain. The overproducing phenotype was related to the enhancement of antagonistic activities against Bacillus cereus. HPLC peaks of surfactin for recombinant fmbR-1 showed patterns of lipopeptides similar to those of the wild-type strain, and surfactin production of the recombinant fmbR-1 was up to about fivefold greater than that of the wild-type strain without induction by isopropyl beta--1-thiogalactopyranoside. However, the production of surfactin increased to about 10-fold more than that of the wild-type strain when it was induced by isopropyl beta--1-thiogalactopyranoside.

[Cloning and expression of organic solvent tolerant lipase gene from Staphylococcus saprophyticus M36]

Lipases are important biocatalysts that are widely used in food processing and bio-diesel production. However, organic solvents could inactivate some lipases during applications. Therefore, the efficient cloning and expression of the organic solvent-tolerant lipase is important to its application. In this work, we first found out an organic solvent-tolerant lipase from Staphylococcus saprophyticus M36 and amplified the 741 bp Lipase gene lip3 (GenBank Accession No. FJ979867), by PCR, which encoded a 31.6 kD polypeptide of 247 amino acid residues. But the lipase shared 83% identity with tentative lip3 gene of Staphylococcus saprophyticus (GenBank Accession No. AP008934). We connected the gene with expression vector pET-DsbA, transformed it into Escherichia coli BL21 (DE3), and obtained the recombinant pET-DsbA-lip3. With the induction by 0.4 mmol/L of isopropyl beta-D-thiogalactopyranoside at pH 8.0, OD600 1.0, 25 degrees C for 12 h, the lipase activity reached up to 25.8 U/mL. The lipase expressed was stable in the presence of methanol, n-hexane, and isooctane, n-heptane.

Effect of high-dose methylprednisolone treatment on Th17 cells in patients with multiple sclerosis in relapse

OBJECTIVES

Growing evidences have suggested that Th17 cells are involved in the pathogenic mechanisms of multiple sclerosis (MS). Treatment with high-dose intravenous methylprednisolone (IVMP) has beneficial effects on functional recovery in patients with MS during relapse. The present study was designed to analyze the influences of IVMP on Th17 cells in patients with MS after a 5-day high-dose IVMP treatment.

MATERIALS AND METHODS

Th17 cell count and the production of IL-17 in peripheral blood mononuclear cells (PBMCs) were measured using flow cytometry and ELISA respectively. Quantitative real-time PCR was performed to analyze the mRNA expression of Th17 cell-related factors (IL-17, RORc and IL-23R) in PBMCs.

RESULTS

A significant reduction in IL-17 production and Th17 cells count in PBMCs was found in patients with MS after IVMP treatment. Moreover, the expression of IL-17, IL-23R and RORc mRNA decreased significantly after IVMP treatment.

CONCLUSIONS

Treatment with methylprednisolone has a suppressive effect on Th17 cells and may be related to its clinical efficiency.

Identification of fengycin homologues from Bacillus subtilis with ESI-MS/CID

Bacillus subtilis fmbJ (CGMCC no.0943) was used to produce lipopeptides antibiotics fengycin. The fengycin mixture was precipitated with 6N HCl and extracted by methanol. Electrospray ionization mass spectrometry/collision-induced dissociation (ESI-MS/CID) were used to analyze the fengycin mixture. In the ESI-MS/CID spectra of fengycin molecular ions, production ions (m/z 1080, m/z 966, m/z 1108 and m/z 994) were always detected. Therefore, these production ions (m/z 1080, m/z 966, m/z 1108 and m/z 994) could be used as fingerprints to quickly detect fengycin A and fengycin B. By the method of ESI-MS/CID, six homologues of fengycin A with C14 to 19 and four homologues of fengycin B with C14 to 17 were characterized. The method will be useful for rapidly determining whether a strain produces fengycin homologues.

Study on the antibiotic activity of microcapsule curcumin against foodborne pathogens

Curcumin as an edible natural pigment has several biological activities but its use as a food colorant and preservative is restricted due to low stability and insolubility in water. Stabilizing it with microencapsulation to obtain microcapsule curcumin can improve its stability and solubility. The microcapsule curcumin was studied for their antibacterial and antifungal activities against some foodborne pathogens and spoilage microbe such as Escherichia coli, Yersinia enterocolitica, Staphylococcus aureus, Bacillus subtilis, Bacillus cereus, Aspergillus niger, Penicllium notatum, and Saccharomyces cerevisiae. It exhibited broad spectrum inhibitory effect against all organisms by Oxford cup methods, and its minimum inhibitory concentrations (MIC) were determined by agar dilution method and ranged from 15.7 to 250 microg/mL. For the selected microorganisms, its antibacterial activity was more pronounced against Gram-positive bacteria than Gram-negative bacteria. Furthermore, its antifungal activity is much better than antibacterial activity. Microcapsule curcumin remains in antibacterial and antifungal activities after microencapsulation, which can be potential colorant and preservative in food industry.

New hypotheses on the function of the avian shell gland derived from microarray analysis comparing tissue from juvenile and sexually mature hens

Activation of the shell gland region of the avian oviduct is mediated by ovarian steroids. To understand more extensively how shell glands are maintained and function, we have compared gene expression in the shell glands from juvenile and laying hens using a chicken cDNA microarray. Average expression profiles of juvenile and sexually mature shell glands were compared resulting in the identification of 266 differentially regulated genes. Reverse transcription quantitative polymerase chain reaction confirmed expression differences. The differentially expressed genes included several with known involvement in shell gland function, including ion transport and shell matrix proteins. There were also many unpredicted differentially expressed genes, and for some we propose hypotheses for their functions. These include those encoding (a) osteoprotegerin, a decoy death receptor for receptor activator of nuclear factor NFkB ligand (RANKL) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), that in the shell gland, may prevent apoptosis and/or may have an endocrine effect by preventing RANKL's action on bone osteoclasts that mobilize stored calcium; (b) prostatic acid phosphatase (ACPP) and prostate stem cell antigen (PSCA) that could play a role in sperm physiology within the shell gland; (c) urea transporter (SLC14A2) that could provide a novel anti-microbial defence; (d) bactericidal/permeability-increasing protein-like 2 (BPIL2), and other potential anti-microbials that have not previously been documented in the chicken. These new hypotheses, if borne out experimentally, will lead to a greater understanding of shell gland function including the processes involved in eggshell formation and anti-microbial activity.