The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
John Cullum - One of the best experts on this subject based on the ideXlab platform.
-
The pyrroloquinoline quinone synthesis genes of Gluconobacter Oxydans.
FEMS Microbiology Letters, 2000Co-Authors: Marius Felder, Ghulam Nabi Qazi, Arun Gupta, Vijeshwar Verma, Anil Kumar, John CullumAbstract:A Tn5-induced glucose dehydrogenase (GDH) deficient mutant of Gluconobacter Oxydans IFO 3293 was characterised. DNA sequencing showed that the insertion site occurred in an open reading frame with homology to the pqqE gene. It was shown that acid production could be restored by addition of the coenzyme pyrroloquinoline quinone (PQQ) to the medium. The pqq cluster of G. Oxydans ATCC 9937 was cloned and sequenced. It has five genes pqqA–E. The cluster could complement the Tn5-induced mutation in IFO 3293. Pulsed-field gel electrophoresis suggested that the pqq genes are not closely linked to the ribF gene that produces the riboflavin cofactor for the gluconic acid dehydrogenase.
-
A mutant of Gluconobacter Oxydans deficient in gluconic acid dehydrogenase
FEMS microbiology letters, 1999Co-Authors: Arun Gupta, Vijeshwar Verma, Marius Felder, John Cullum, Gulam Nabi QaziAbstract:Gluconobacter Oxydans ATCC 9937 was subjected to transposon mutagenesis using Tn5. A non-pigmented mutant was shown to be defective in gluconic acid dehydrogenase and to produce gluconic acid from glucose, whereas the parent strain produced 2,5-diketogluconic acid. Cloning and sequencing of the region containing the Tn5 insertion showed that the insertion point occurred in an open reading frame homologous (42% amino acid identity) to the ribF genes of Pseudomonas fluorescens and Escherichia coli. The resulting lack of a riboflavin cofactor would explain the loss of enzyme activity.
-
Characterisation of plasmids from diketogluconic acid producing strains of Gluconobacter Oxydans
Journal of biotechnology, 1994Co-Authors: Vijeshwar Verma, Marius Felder, John Cullum, G.n. QaziAbstract:Gluconobacter Oxydans ATCC 9937, which produces 2,5-diketogluconic acid, an intermediate in vitamin C synthesis, has three plasmids of sizes 27.7 kb (pVJ1), 12.3 kb (pVJ2) and 18 kb (pVJ4). A restriction map was constructed of pVJ1. A potential glucose dehydrogenase gene was located on pVJ1 using the polymerase chain reaction with heterologous primers. Two other G. Oxydans strains had no detectable plasmid DNA (IFO 12258) and a plasmid (pVJ3) of 9.4 kb (IFO 3293), respectively.
Xuepeng Yang - One of the best experts on this subject based on the ideXlab platform.
-
Characterization of enzymes in the oxidation of 1,2-propanediol to D: -(-)-lactic acid by Gluconobacter Oxydans DSM 2003.
Molecular biotechnology, 2010Co-Authors: Liujing Wei, Xuepeng Yang, Jinping Lin, Keliang Gao, Shengli Yang, Qiang Hua, Dongzhi WeiAbstract:Although Gluconobacter Oxydans can convert 1,2-propanediol to d-(−)-lactic acid, the enzyme(s) responsible for the conversion has remain unknown. In this study, the membrane-bound alcohol dehydrogenase (ADH) of Gluconobacter Oxydans DSM 2003 was purified and confirmed to be essential for the process of d-(−)-lactic acid production by gene knockout and complementation studies. A 25 percent decrease in d-(−)-lactic acid production was found for the aldehyde dehydrogenase (ALDH) deficient strain of G. Oxydans DSM 2003, indicating that this enzyme is involved in the reaction but not necessary. It is the first report that reveals the function of ADH and ALDH in the biooxidation of 1,2-propanediol to d-(−)-lactic acid by G. Oxydans DSM 2003.
-
High cell density fermentation of Gluconobacter Oxydans DSM 2003 for glycolic acid production
Journal of industrial microbiology & biotechnology, 2009Co-Authors: Guodong Wei, Xuepeng Yang, Jinping Lin, Tula Gan, Wenyu Zhou, Dongzhi WeiAbstract:Gluconobacter Oxydans has a lower biomass yield. Uniform design (UD) was applied to determine the optimum composition of the critical media and their mutual interactions for increased biomass yield of Gluconobacter Oxydans DSM 2003 in shake flasks. Fed-batch fermentation process for biomass was optimized in a 3.7-l fermentor. By undertaking a preliminary and improved fed-batch fermentation-process strategy, a cell density of 6.0 g/l (DCW) was achieved in 22 h and 14.1 g/l (DCW) in 35 h, which is the highest cell density of G. Oxydans produced thus far in a 3.7-l bioreactor. The biomass production was increased by 135% compared with that using the original cultivation strategy. Bioconversion of ethylene glycol to glycolic acid was catalyzed by the resting cells of G. Oxydans DSM 2003, and conversion rate reached 86.7% in 48 h. In summary, the approach including high-density fermentation of G. Oxydans DSM 2003 and bioconversion process was established and proved to be an effective method for glycolic acid production.
-
membrane bound pyrroloquinoline quinone dependent dehydrogenase in Gluconobacter Oxydans m5 responsible for production of 6 2 hydroxyethyl amino 6 deoxy l sorbose
Applied and Environmental Microbiology, 2008Co-Authors: Xuepeng YangAbstract:A membrane-bound protein purified from Gluconobacter Oxydans M5 was confirmed to be a pyrroloquinoline quinone-dependent d-sorbitol dehydrogenase. Gene disruption and complementation experiments demonstrated that this enzyme is responsible for the oxidation of 1-(2-hydroxyethyl) amino-1-deoxy-d-sorbitol (1NSL) to 6-(2-hydroxyethyl) amino-6-deoxy-l-sorbose (6NSE), which is the precursor of an antidiabetic drug, miglitol.
Marius Felder - One of the best experts on this subject based on the ideXlab platform.
-
The pyrroloquinoline quinone synthesis genes of Gluconobacter Oxydans.
FEMS Microbiology Letters, 2000Co-Authors: Marius Felder, Ghulam Nabi Qazi, Arun Gupta, Vijeshwar Verma, Anil Kumar, John CullumAbstract:A Tn5-induced glucose dehydrogenase (GDH) deficient mutant of Gluconobacter Oxydans IFO 3293 was characterised. DNA sequencing showed that the insertion site occurred in an open reading frame with homology to the pqqE gene. It was shown that acid production could be restored by addition of the coenzyme pyrroloquinoline quinone (PQQ) to the medium. The pqq cluster of G. Oxydans ATCC 9937 was cloned and sequenced. It has five genes pqqA–E. The cluster could complement the Tn5-induced mutation in IFO 3293. Pulsed-field gel electrophoresis suggested that the pqq genes are not closely linked to the ribF gene that produces the riboflavin cofactor for the gluconic acid dehydrogenase.
-
A mutant of Gluconobacter Oxydans deficient in gluconic acid dehydrogenase
FEMS microbiology letters, 1999Co-Authors: Arun Gupta, Vijeshwar Verma, Marius Felder, John Cullum, Gulam Nabi QaziAbstract:Gluconobacter Oxydans ATCC 9937 was subjected to transposon mutagenesis using Tn5. A non-pigmented mutant was shown to be defective in gluconic acid dehydrogenase and to produce gluconic acid from glucose, whereas the parent strain produced 2,5-diketogluconic acid. Cloning and sequencing of the region containing the Tn5 insertion showed that the insertion point occurred in an open reading frame homologous (42% amino acid identity) to the ribF genes of Pseudomonas fluorescens and Escherichia coli. The resulting lack of a riboflavin cofactor would explain the loss of enzyme activity.
-
Characterisation of plasmids from diketogluconic acid producing strains of Gluconobacter Oxydans
Journal of biotechnology, 1994Co-Authors: Vijeshwar Verma, Marius Felder, John Cullum, G.n. QaziAbstract:Gluconobacter Oxydans ATCC 9937, which produces 2,5-diketogluconic acid, an intermediate in vitamin C synthesis, has three plasmids of sizes 27.7 kb (pVJ1), 12.3 kb (pVJ2) and 18 kb (pVJ4). A restriction map was constructed of pVJ1. A potential glucose dehydrogenase gene was located on pVJ1 using the polymerase chain reaction with heterologous primers. Two other G. Oxydans strains had no detectable plasmid DNA (IFO 12258) and a plasmid (pVJ3) of 9.4 kb (IFO 3293), respectively.
Vijeshwar Verma - One of the best experts on this subject based on the ideXlab platform.
-
The pyrroloquinoline quinone synthesis genes of Gluconobacter Oxydans.
FEMS Microbiology Letters, 2000Co-Authors: Marius Felder, Ghulam Nabi Qazi, Arun Gupta, Vijeshwar Verma, Anil Kumar, John CullumAbstract:A Tn5-induced glucose dehydrogenase (GDH) deficient mutant of Gluconobacter Oxydans IFO 3293 was characterised. DNA sequencing showed that the insertion site occurred in an open reading frame with homology to the pqqE gene. It was shown that acid production could be restored by addition of the coenzyme pyrroloquinoline quinone (PQQ) to the medium. The pqq cluster of G. Oxydans ATCC 9937 was cloned and sequenced. It has five genes pqqA–E. The cluster could complement the Tn5-induced mutation in IFO 3293. Pulsed-field gel electrophoresis suggested that the pqq genes are not closely linked to the ribF gene that produces the riboflavin cofactor for the gluconic acid dehydrogenase.
-
A mutant of Gluconobacter Oxydans deficient in gluconic acid dehydrogenase
FEMS microbiology letters, 1999Co-Authors: Arun Gupta, Vijeshwar Verma, Marius Felder, John Cullum, Gulam Nabi QaziAbstract:Gluconobacter Oxydans ATCC 9937 was subjected to transposon mutagenesis using Tn5. A non-pigmented mutant was shown to be defective in gluconic acid dehydrogenase and to produce gluconic acid from glucose, whereas the parent strain produced 2,5-diketogluconic acid. Cloning and sequencing of the region containing the Tn5 insertion showed that the insertion point occurred in an open reading frame homologous (42% amino acid identity) to the ribF genes of Pseudomonas fluorescens and Escherichia coli. The resulting lack of a riboflavin cofactor would explain the loss of enzyme activity.
-
Characterisation of plasmids from diketogluconic acid producing strains of Gluconobacter Oxydans
Journal of biotechnology, 1994Co-Authors: Vijeshwar Verma, Marius Felder, John Cullum, G.n. QaziAbstract:Gluconobacter Oxydans ATCC 9937, which produces 2,5-diketogluconic acid, an intermediate in vitamin C synthesis, has three plasmids of sizes 27.7 kb (pVJ1), 12.3 kb (pVJ2) and 18 kb (pVJ4). A restriction map was constructed of pVJ1. A potential glucose dehydrogenase gene was located on pVJ1 using the polymerase chain reaction with heterologous primers. Two other G. Oxydans strains had no detectable plasmid DNA (IFO 12258) and a plasmid (pVJ3) of 9.4 kb (IFO 3293), respectively.
-
Intergeneric protoplast fusion between Gluconobacter Oxydans and Corynebacterium species.
Journal of biotechnology, 1992Co-Authors: Vijeshwar Verma, Ghulam Nabi Qazi, Rajinder ParshadAbstract:Abstract Intergeneric protoplast fusion between 2,5-diketo-gluconic acid producing Gluconobacter Oxydans (ATCC 9937) and a mutant strain of Corynebacterium species (ATCC 31090), capable of reducing 2,5-diketo-gluconic acid to 2-keto- l -gulonic acid, a penultimate step in vitamin C production) resulted in viable recombinants. Some of the fusion products exhibited the capacity to convert d -glucose to 2-keto- l -gulonic acid, but the conversion rate is low.
-
Diketo-gluconate fermentation by Gluconobacter Oxydans
Enzyme and Microbial Technology, 1991Co-Authors: Ghulam Nabi Qazi, Rajinder Parshad, Vijeshwar Verma, C.l. Chopra, R. Buse, Michael Träger, Ulfert OnkenAbstract:Abstract Production of 2,5-diketogluconate by Gluconobacter Oxydans (ATCC9937) in two types of reactors, namely, airlift and stirred fermentors, is described. Accumulation of diketo-acid is shown to be dependent on the pH of the medium. Oxidation of gluconate to 2,5-diketogluconate in Gluconobacter Oxydans is described as a specific reaction carried out through an intermediate of 2-ketogluconate rather than 5-ketogluconate. The enzyme profile of the culture depicting two distinct phases, i.e. direct glucose oxidation and gluconate oxidation, is described.
Dongzhi Wei - One of the best experts on this subject based on the ideXlab platform.
-
Effective improvement of the activity of membrane-bound alcohol dehydrogenase by overexpression of adhS in Gluconobacter Oxydans
Biotechnology letters, 2016Co-Authors: Huan Zhang, Jinping Lin, Ming Sun, Lulu Shi, Dongzhi WeiAbstract:Objectives To investigate the roles of adhS, which encodes the AdhS subunit of membrane-bound alcohol dehydrogenase (mADH) in Gluconobacter Oxydans DSM2003, and to rationally improve mADH activity.
-
Phosphorylation of HPr by HPr Kinase in Gluconobacter Oxydans 621H
Protein and peptide letters, 2014Co-Authors: Ping Zhang, Fengqing Wang, Dongzhi WeiAbstract:DNA sequencing has revealed that Gluconobacter Oxydans may contain an incomplete phosphoenolpyruvate: carbohydrate phosphotransferase system (PTS), but the function of individual members of the system remains unknown. Here we demonstrated that the predicted histidine protein HPr, an essential component of PTS, can be phosphorylated by a predicted HPr kinase in G. Oxydans, where Ser54 in HPr is the site responsible for such a phosphorylation. The discovery implies that G. Oxydans may regulate PTS activity in a way similar to that identified in some Gram-positive bacteria with low GC content.
-
Immobilization of Gluconobacter Oxydans by Entrapment in Porous Chitosan Sponge
Journal of bioprocessing & biotechniques, 2013Co-Authors: Cunxun Wang, Dongzhi Wei, Xu Zhou, Yuhong RenAbstract:The porous chitosan sponge was prepared using NaHCO3 as the porogen and used to immobilize Gluconobacter Oxydans. Under the optimum conditions, the activity recovery of the immobilized cells reached 92%. The morphology characterization of the immobilized cells revealed that the cells were attached to the surface of the pores (100-400μm) which were well distributed in the chitosan sponge. The valuation of cell activity showed that the immobilized cells displayed enhanced pH and thermal stability compared to free cells. Furthermore, the immobilized cells retained 74% of its origin activity after 12 repeated reaction cycles separated by filtration.
-
Characterization of a novel dextran produced by Gluconobacter Oxydans DSM 2003.
Applied microbiology and biotechnology, 2011Co-Authors: Shu Wang, Jinping Lin, Xiangzhao Mao, Hualei Wang, Dongzhi WeiAbstract:A novel water-soluble dextran was synthesized from maltodextrin by cell-free extract of Gluconobacter Oxydans DSM 2003. The dextran was purified by size exclusion chromatography, and the structure was determined by Fourier transform infrared spectroscopy, nuclear magnetic resonance, and gas chromatography–mass spectrometer. Based on the spectral data, we found that the dextran contained only d-glucose residues. The ratio of nonreducing end glucopyranosyl (Glcp) to 6-linked Glcp to 4,6-linked Glcp was estimated to be 8.62:78.79:12.59 by methylation analysis. This result indicated the existence of a small proportion of α(1,4) branches in α(1,6) glucosyl linear chains. Here, we reported the first time a novel dextran was synthesized by G. Oxydans DSM 2003.
-
Highly Selective Oxidation of Benzyl Alcohol Using Engineered Gluconobacter Oxydans in Biphasic System
Current microbiology, 2010Co-Authors: Jinping Lin, Dongzhi WeiAbstract:The Gluconobacter Oxydans M5 with disruption of the pyrroloquinoline quinine-dependent membrane-bound aldehyde dehydrogenase (ALDH) was used for the oxidation of benzyl alcohol. The selectivity toward benzaldehyde showed an obvious increase for the engineered strain, which reached the 67.3%, while the wild strain had only 2.8%. Meantime, the aqueous/isooctane (1:1) biphasic system was used for the further improvement of selectivity. By these methods, nearly 100% selectivity and conversion rate could be obtained within 1 h at the optimum initial benzyl alcohol concentration of 5.0 g/l.