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Extracellular Production (extracellular + production)

Distribution by Scientific Domains

Life Sciences	71%

Selected Abstracts

Expression and secretion of an ,-amylase gene from a native strain of Bacillus licheniformis in Escherichia coli by T7 promoter and putative signal peptide of the gene

JOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2003
M. Shahhoseini
Abstract The gene encoding a hyperthermostable , -amylase from a Bacillus licheniformis native strain was cloned in pET24d transcription vector containing T7 promoter, and expressed in Escherichia coli BL21(DE3) cells. Having confirmed the , -amylase activity through activity staining method on SDS,PAGE gel, the yields of production were determined in two separated intra and inter-cellular phases and compared using enzymatic assay methods. Extracellular production of the active recombinant enzyme implies the recognition of the putative signal peptide of this Bacillus sp. by E. coli secretory system. This may be because of the amino acid sequence of this signal peptide which covers all the structural parameters of a standard signal peptide processed by Lep B, the major signal peptidase in E. coli secretory system. This study recommends the use of this signal peptide for extracellular production of other foreign proteins in E. coli. [source]

Possible role of reactive chlorine in microbial antagonism and organic matter chlorination in terrestrial environments

ENVIRONMENTAL MICROBIOLOGY, Issue 6 2009
Per Bengtson
Summary Several studies have demonstrated that extensive formation of organically bound chlorine occurs both in soil and in decaying plant material. Previous studies suggest that enzymatic formation of reactive chlorine outside cells is a major source. However, the ecological role of microbial-induced extracellular chlorination processes remains unclear. In the present paper, we assess whether or not the literature supports the hypothesis that extracellular chlorination is involved in direct antagonism against competitors for the same resources. Our review shows that it is by no means rare that biotic processes create conditions that render biocidal concentrations of reactive chlorine compounds, which suggest that extracellular production of reactive chlorine may have an important role in antagonistic microbial interactions. To test the validity, we searched the UniprotPK database for microorganisms that are known to produce haloperoxidases. It appeared that many of the identified haloperoxidases from terrestrial environments are originating from organisms that are associated with living plants or decomposing plant material. The results of the in silico screening were supported by various field and laboratory studies on natural chlorination. Hence, the ability to produce reactive chlorine seems to be especially common in environments that are known for antibiotic-mediated competition for resources (interference competition). Yet, the ability to produce haloperoxidases is also recorded, for example, for plant endosymbionts and parasites, and there is little or no empirical evidence that suggests that these organisms are antagonistic. [source]

Production of d -(,)-3-hydroxyalkanoic acid by recombinant Escherichia coli

FEMS MICROBIOLOGY LETTERS, Issue 1 2003
Kai Zhao
Abstract Pathways for extracellular production of chiral d -(,)-3-hydroxybutyric acid (3HB) and d -(,)-3-hydroxyalkanoic acid (mcl-3HA) were constructed by co-expression of genes of ,-ketothiolase (phbA), acetoacetyl-CoA reductase (phbB) and 3-hydroxyacyl-ACP CoA transacylase (phaG), respectively, in Escherichia coli strain DH5,. The effect of acrylic acid and glucose on production of both 3HB and mcl-3HA was investigated. It was found that the addition of acrylic acid significantly increased production of 3HB and mcl-3HA consisting of 3-hydroxyoctanoic acid and 3-hydroxydecanoic acid in a ratio of 1:3 from 199 mg l,1 to 661 mg l,1 and from 27 mg l,1 to 135 mg l,1, respectively, in shake flask studies when glucose was present in the medium at the very beginning of fermentation. The timing of glucose addition had no effect on 3HB production. In contrast, mcl-3HA production was affected by glucose addition, an mcl-3HA concentration of 193 mg l,1 was obtained when glucose was added to the culture at 12 h. A more than seven-fold increase was obtained when compared with that in medium containing glucose at the beginning of fermentation. However, a decrease in production of 3HB and mcl-3HA was found when glucose was added at 12 h to the culture containing acrylic acid. The repressive effect of acrylic acid on acetic acid production was also evaluated and discussed. [source]

Expression and secretion of an ,-amylase gene from a native strain of Bacillus licheniformis in Escherichia coli by T7 promoter and putative signal peptide of the gene

High-level extracellular production of penicillin acylase by genetic engineering of Escherichia coli

JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 10 2001
Wen-Jer Lin
Abstract The extracellular production of penicillin acylase (PAC) in genetically engineered Escherichia coli by coexpression of the brp gene encoding bacteriocin release protein (BRP) and the pac gene was demonstrated. Cell physiology was affected while PAC was released into the medium, depending on the strategy for brp expression. The performance for the production and release of PAC was optimized by taking several culture parameters, including host, inducer (mitomycin C) concentration, and induction timing for brp expression, into consideration. The effect of PAC release on inclusion body formation was also investigated. It was observed that the amount of inclusion bodies was significantly affected by brp expression. A reason for the limitation of PAC production and a strategy for resolving this problem are proposed. © 2001 Society of Chemical Industry [source]

Production of hydrogen peroxide is responsible for the induction of apoptosis by hydroxytyrosol on HL60 cells

MOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 7 2009
Roberto Fabiani
Abstract Hydroxytyrosol [3,4-dihydroxyphenylethanol (3,4-DHPEA)], a phenolic compound found exclusively in olive oil, exerts growth-suppressive and pro-apoptotic effects on different cancer cells. Although some molecular mechanisms involved in the pro-apoptotic activity of 3,4-DHPEA have been proposed, the initial stress signals responsible of this phenomenon are not known. Our aim was to assess the involvement of reactive oxygen species as mediators of apoptosis induced by 3,4-DHPEA on HL60 cells. Apoptosis was determined by analyzing the nuclear fragmentation by both fluorescence microscopy and flow cytometry. The externalization of phosphatidylserine was evidenced using an Annexin V-FITC kit. The concentration of H2O2 in the culture medium was measured by the ferrous ion oxidation-xylenol orange method. The pro-apoptotic effect of 3,4-DHPEA (100 ,M) was prevented by N -acetyl-cysteine, ascorbate, and ,-tocopherol. Catalase suppressed the 3,4-DHPEA-induced apoptosis, while the Fe(II)-chelating reagent o -phenantroline showed no effect, suggesting the involvement of H2O2 but not of OH,. Indeed, 3,4-DHPEA caused accumulation of H2O2 in the culture medium. Tyrosol (p -hydroxyphenylethanol) and caffeic acid, compounds structurally similar to 3,4-DHPEA but not able to generate H2O2, did not induce an appreciable apoptotic effect. This is the first study demonstrating that apoptosis induction by 3,4-DHPEA is mediated by the extracellular production of H2O2. [source]

Dapsone suppresses human neutrophil superoxide production and elastase release in a calcium-dependent manner

BRITISH JOURNAL OF DERMATOLOGY, Issue 5 2005
T. Suda
Summary Background, Dapsone (4,4,-diaminodiphenyl sulphone) is a powerful therapeutic tool in many skin diseases including neutrophilic dermatoses. The drug has an outstanding therapeutic efficacy against many skin diseases characterized by neutrophil-rich infiltrates; however, mechanisms of its action are poorly understood. Objectives, We investigated the effects of dapsone on respiratory and secretory functions of human neutrophils triggered by the chemotactic peptide N -formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP), the physiological agonist C5a, and phorbol myristate acetate (PMA). Methods, Human neutrophils were isolated from venous blood obtained from healthy donors. We detected extracellular production of superoxide (O2,) by cytochrome C reduction assay, and intracellular production of O2, by flow cytometry. Neutrophil elastase release was measured by the cleavage of the specific elastase substrate N -methoxysuccinyl-Ala-Ala-Pro-Val- p -nitroanilide. Measurement of cytosolic free calcium concentration was performed using the calcium-reactive fluorescence probe, Fluo-3. Results, Dapsone suppressed intra- and extracellular production of O2, and elastase release triggered by fMLP and C5a, but not by PMA. Both fMLP and C5a signalled the above pathways by inducing calcium influx, but PMA functions bypassed calcium influx. Dapsone was capable of antagonizing the induction of calcium influx. Conclusions, These findings suggest that one mechanism of the anti-inflammatory action of dapsone is inhibition of calcium-dependent functions of neutrophils including release of tissue-damaging oxidants and proteases in the affected skin. [source]