Gluconobacter oxydans WD膜结合山梨醇脱氢酶基因在E.coli中的克隆表达

本研究构建了四株含有氧化葡萄糖酸杆菌山梨醇脱氢酶基因的重组大肠杆菌,并初步探究SldB和SldA亚基在山梨醇脱氢酶转化甘油反应中的作用。将pET28a、pETduet与PCR扩增的目的基因连接,构建单启动子调控重组质粒pET28a-sldB、pET28a-sldA、pET28a-sldBA和双启动子调控重组质粒pETduet-sldB'-sldA'。只有含pET28a-sldBA和pETduet-sldB'-sldA'的重组菌具有转化甘油的活性,表明G.oxydans WD的山梨醇脱氢酶催化甘油脱氢需要SldB和SldA亚基的共同作用。串联基因sldBA的蛋白表达结果与双启动子控制sldB和sldA基因蛋白表达结果基本相同,表明位于sldB基因末端的sldA的RBS序列可被E.coli C43的核糖体识别。     

Gluconobacter oxydans NH-10中NAD+型阿拉伯糖醇脱氢酶基因敲除菌株的构建

氧化葡萄糖酸杆菌Gluconobacter oxydans NH-10能够转化D-阿拉伯糖醇,经木酮糖生成木糖醇,但该菌中存在的NAD+型D-阿拉伯糖醇脱氢酶可将中间产物D-木酮糖还原成D-阿拉伯糖醇,从而影响木糖醇的积累.利用同源重组基因敲除的方法构建G.oxydans NH-10 NAD+型D-阿拉伯糖醇脱氢酶( sArDH)基因敲除突变株.PCR结果显示:sArDH基因在1株重组菌中完全被卡那抗性基因替代,表明sArDH基因敲除突变体构建成功.生物学特性鉴定显示:突变菌在菌落形态,生长状态方面与原始菌无明显差异.静息细胞转化D-阿拉伯糖醇结果显示,突变株不存在还原D-木酮糖产D-阿拉伯糖醇的逆反应,终产物木糖醇的产量有所提高.     

Molecular cloning and functional expression of d-arabitol dehydrogenase gene from Gluconobacter oxydans in Escherichia coli

A NADP-dependent d-arabitol dehydrogenase gene was cloned from Gluconobacter oxydans CGMCC 1.110 and functionally expressed in Escherichia coli. With d-arabitol as sole carbon source, E. coli transformants grew rapidly in minimal medium, and produced d-xylulose. The enzymatic properties of the 29kDa enzyme were documented. The DNA sequence surrounding the gene suggested that it is part of an operon with several components of a sugar alcohol transporter system, and the d-arabitol dehydrogenase gene belongs to the short-chain dehydrogenase family.     

Vinyl ketone reduction by three distinct Gluconobacter oxydans 621H enzymes

Three cytosolic NADPH-dependent flavin-associated proteins (Gox2107, Gox0502, and Gox2684) from Gluconobacter oxydans 621H were overproduced in Escherichia coli, and the recombinant enzymes were purified and characterized. Apparent native molecular masses of 65.2, 78.2, and 78.4 kDa were observed for Gox2107, Gox0502, and Gox2684, corresponding to a trimeric structure for Gox2107 and dimers for Gox0502 and Gox2684. Analysis of flavin content revealed Gox2107 was flavin adenine dinucleotide dependent, whereas Gox0502 and Gox2684 contained flavin mononucleotide. The enzymes were able to reduce vinyl ketones and quinones, reducing the olefinic bond of vinyl ketones as shown by ¹H nuclear magnetic resonance. Additionally, Gox0502 and Gox2684 stereospecifically reduced 5S-(+)-carvone to 2R,5S-dihydrocarvone. All enzymes displayed highest activities with 3-butene-2-one and 1,4-naphthoquinone. Gox0502 and Gox2684 displayed a broader substrate spectrum also reducing short-chain α-diketones, whereas Gox2107 was most catalytically efficient.     

Purification and Properties of Two Different Dihydroxyacetone Reductases in Gluconobacter suboxydans Grown on Glycerol

It is well known that in oxidative fermentation microbial growth is improved by the addition of glycerol. In a wild strain, glycerol was converted rapidly to dihydroxyacetone (DHA) quantitatively in the early growth phase by the action of quinoprotein glycerol dehydrogenase (GLDH), and then DHA was incorporated into the cells by the early stationary phase. Two DHA reductases (DHARs), NADH-dependent (NADH-DHAR) (EC 1.1.1.6) and NADPH-dependent (NADPH-DHAR) (EC 1.1.1.156), were detected in the same cytoplasm of Gluconobacter suboxydans IFO 3255. The former appeared to be inducible and labile in nature while the latter was constitutive and stable. The two DHARs were separated each other and were finally purified to crystalline enzymes. This report might be the first one dealing with NADPH-DHAR that has been crystallized. The two DHARs were specific only to DHA reduction to glycerol and thus contributed to cytoplasmic DHA metabolism, resulting in an improved biomass yield with the addition of glycerol.     

5-Keto-D-fructose production from sugar alcohol by isolated wild strain Gluconobacter frateurii CHM 43

ABSTRACT

Gluconobacter frateurii CHM 43 have D-mannitol dehydrogenase (quinoprotein glycerol dehydrogenase) and flavoprotein D-fructose dehydrogenase in the membranes. When the two enzymes are functional, D-mannitol is converted to 5-keto-D-fructose with 65% yield when cultivated on D-mannitol. 5-Keto-D-fructose production with almost 100% yield was realized with the resting cells. The method proposed here should give a smart strategy for 5-keto-D-fructose production.     

弱氧化葡糖杆菌ddsA基因在大肠杆菌不同宿主菌中的表达

泛醌（辅酶Q）在生物体氧化呼吸链中作为重要的质子和电子传递物质。聚十异戊烯焦磷酸合成酶催化辅助酶Q10的侧链的生物合成。为了获得高产辅助酶Q10的菌株,将选择了10种不同大肠杆菌宿主菌用于弱氧化葡糖杆菌的聚十异戊烯焦磷酸合成酶基因ddsA的表达,通过产物分析证实该基因能在大肠杆菌中表达出有活性的聚十异戊烯焦磷酸合成酶,使大肠杆菌合成了辅酶Q10。此外,还发现在Escherichia coli HB101这一菌株中,ddsA的表达使辅酶Q10的产量略超过了在野生型中占主导地位的辅酶Q8的产量。该结果证明了利用大肠杆菌大规模发酵生产辅酶Q10的可能性。     

利用山梨糖脱氢酶活性筛选氧化葡糖杆菌PQQ合成基因簇

【目的】利用山梨糖脱氢酶醌酶活性从氧化葡糖杆菌H24中分离PQQ生物合成基因簇。【方法】利用ptsG位点整合sdh基因的大肠杆菌JM109作为宿主菌构建了氧化葡糖杆菌H24的基因组DNA文库。通过山梨糖脱氢酶活性检测,从文库中筛选具有PQQ合成能力的单菌落并进行亚克隆。【结果】从氧化葡糖杆菌H24的基因组文库中筛选得到一株具有山梨糖脱氢酶活性的单菌落,亚克隆后序列分析显示插入片段全长5400bp,对应5个编码框(pqqABCDE),与其他细菌PQQ生物合成基因簇有很高的序列同源性。【结论】利用山梨糖脱氢酶醌酶活性成功从氧化葡糖杆菌H24中分离克隆得到了PQQ生物合成基因簇pqqABCDE。     

外源基因在大肠杆菌中表达研究进展

近年来,基因工程技术的迅速发展,大量有价值的蛋白质大肠杆菌中获得了高表达。多种表达系统的完善与发展,及蛋白质分离纯化技术的提高,异源蛋白的产量与纯度已不再是困扰人们的主要问题,人们开始更多地关注异源蛋白的活性,比活性及异源蛋白的正确性,完整性。随着这些问题的解决,重组蛋白的应用才能真正走向成熟。     

Phylogenetic position of Gluconobacter species as a coherent cluster separated from all Acetobacter species on the basis of 16S ribosomal RNA sequences

Abstract The 16S rRNA sequences from the Gluconobacter species G. asaii G. cerinus and G. frateurii were determined and compared with homologous sequences from published databases and sequences of G. oxydans and Acetobacter species previously described [Sievers M., Ludwig W. and Teuber M. (1994) System. Appl. Microbiol. 17, 189–196]. The Gluconobacter species have unique 16S rRNA sequences and exhibit sequence similarity values of 97.4 to 99.1%, corresponding to 36 to 14 base differences. The phylogenetic tree inferring methods (distance matrix, maximum parsimony and maximum likelihood) show that the species of Gluconobacter form a coherent, closely related cluster. Based on the distance matrix method including Rhodopila globiformis as an outgroup reference organism, Gluconobacter is well separated from Acetobacter .     

Synthesis of 2-keto-L-gulonic acid from gluconic acid by co-immobilized Gluconobacter oxydans and Corynebacterium sp.

2-Keto-L-gulonic acid was produced from gluconic acid using co-immobilized cells of Gluconobacter oxydans and Corynebacterium sp. with 2,5-diketo-D-gluconic acid. Gluconobacter oxydans and Corynebacterium sp. were entrapped together with polyvinylalcohol and alginate. 50 g/l glucose, 50 g/l gluconic acid, and the mixture of equal volume of 50 g/l glucose and 50 g/l gluconic acid were used as substrates. When the ratio of two cells was 1 to 1 with 100 mg cells/ml, the conversion of 2-KLG from gluconic acid was 38% (g/g). © Rapid Science Ltd. 1998     

混合培养中巨大芽孢杆菌对氧化葡萄糖酸杆菌的作用

为查明维生素Ｃ二步发酵混合培养中巨大芽孢杆菌与氧化葡萄糖酸杆菌间的关系,通过生长曲线测定、静息细胞实验及摇瓶发酵实验研究了巨大芽孢杆菌对氧化葡萄糖酸杆菌生长和产生２－酮基－Ｌ－古龙酸作用的影响;采用超滤分离、凝胶层析及聚丙烯酰胺凝胶电泳技术对巨大芽孢杆菌胞外液中具有促进氧化葡萄糖酸杆菌产酸作用的活性物质进行了分离和纯化。结果表明,大菌胞内液和胞外液均可促进小菌生长,大菌胞外液中具有该作用的组分分子     

Selective,High Conversion of D-Glucose to 5-Keto-D-gluoconate by Gluconobacter suboxydans

Selective, high-yield production of 5-keto-D-gluconate (5KGA) from D-glucose by Gluconobacter was achieved without genetic modification. 5KGA production by Gluconobacter suffers byproduct formation of 2-keto-D-gluconate (2KGA). By controlling the medium pH strictly in a range of pH 3.5–4.0, 5KGA was accumulated with 87% conversion yield from D-glucose. The pH dependency of 5KGA formation appeared to be related to that of gluconate oxidizing activity.     

氧化葡糖杆菌sndh-sdh基因簇的克隆表达

目的:从氧化葡糖杆菌H763中克隆sndh-sdh基因簇,在大肠杆菌和氧化葡糖杆菌621H中分别表达山梨酮脱氢酶-山梨糖脱氢酶(SNDH-SDH),并检测其活性。方法与结果:以氧化葡糖杆菌H763基因组DNA为模板,PCR扩增包括启动子、结构基因及终止序列在内的sndh-sdh基因簇,回收3533 bp的扩增产物,连入pMD18T载体,转化至大肠杆菌DH5α中表达;以山梨糖或木糖为底物,DCIP法检测菌体裂解液,DCIP检测液颜色由蓝绿色变为黄色,表明大肠杆菌表达产物具有脱氢酶活性。构建pBBR1MCS2-sndh-sdh载体,通过接合转移导入氧化葡糖杆菌621H,重组葡糖杆菌在以山梨醇或山梨糖为底物的培养基中培养,采用薄层层析检测法检测其培养上清中的代谢产物,层析板上显示了2-酮基-L-古龙酸斑点。结论:重组大肠杆菌DH5α和氧化葡糖杆菌621H中均表达了有脱氢酶活性的SNDH-SDH。     

Isolation and Characterization of Thermotolerant Gluconobacter Strains Catalyzing Oxidative Fermentation at Higher Temperatures

Thermotolerant acetic acid bacteria belonging to the genus Gluconobacter were isolated from various kinds of fruits and flowers from Thailand and Japan. The screening strategy was built up to exclude Acetobacter strains by adding gluconic acid to a culture medium in the presence of 1% D-sorbitol or 1% D-mannitol. Eight strains of thermotolerant Gluconobacter were isolated and screened for D-fructose and L-sorbose production. They grew at wide range of temperatures from 10°C to 37°C and had average optimum growth temperature between 30-33°C. All strains were able to produce L-sorbose and D-fructose at higher temperatures such as 37°C. The 16S rRNA sequences analysis showed that the isolated strains were almost identical to G. frateurii with scores of 99.36-99.79%. Among these eight strains, especially strains CHM16 and CHM54 had high oxidase activity for D-mannitol and D-sorbitol, converting it to D-fructose and L-sorbose at 37°C, respectively. Sugar alcohols oxidation proceeded without a lag time, but Gluconobacter frateurii IFO 3264^T was unable to do such fermentation at 37°C. Fermentation efficiency and fermentation rate of the strains CHM16 and CHM54 were quite high and they rapidly oxidized D-mannitol and D-sorbitol to D-fructose and L-sorbose at almost 100% within 24 h at 30°C. Even oxidative fermentation of D-fructose done at 37°C, the strain CHM16 still accumulated D-fructose at 80% within 24 h. The efficiency of L-sorbose fermentation by the strain CHM54 at 37°C was superior to that observed at 30°C. Thus, the eight strains were finally classified as thermotolerant members of G. frateurii.     

Mutation of Gluconobacter oxydans and Bacillus megaterium in a two-step process of l-ascorbic acid manufacture by ion beam

AIM: To increase the transformation rate of l-sorbose to 2-keto-l-gulonic (2-KLG) acid in a two-step process of l-ascrobic acid manufacture by ion beam. METHODS AND RESULTS: Gluconobacter oxydans (GO29) and Bacillus megaterium (BM80) were used in the present study. Ion implantation was carried out with the heavy ion implantation facility at the institute of Plasma Physics in China. 2-KLG in whole culture broth was determined by iodometry. Mutants were screened by single-colony isolation and 2-KLG accumulation in broth. GO29 and BM80 were implanted by either hydrogen ions (H(+)) or nitrogen ions (N(+)) with various doses, respectively. The average transformation rate of GM112-302 bred by ion beam in Gram-molecule was increased from 79.3 to 94.5% after eight passages in shaking flasks. Furthermore, in 180-ton fermentors in Jiangsu Jiangshan Pharmaceutical Co. Ltd, the transformation rate was stable at 92.0%, indicating a producer could get 0.99 kg of gulonic acid from 1.0 kg of sorbose. CONCLUSION: Ion beam as a new mutation source had potential advantages in breeding. Comparing with original mixture GO29 and BM80, GM112-302 is more efficient in accumulating 2-KLG, especially at the later phase. SIGNIFICANCE AND IMPACT OF THE STUDY: GM112-302 bred by ion beam implantation dramatically increased the transformation rate by 19.2%, which greatly increased efficiency and reduced the cost of l-ascorbic acid manufacture in a two-step process.     

Cloning,characterization and heterologous expression of the Blakeslea trispora gene encoding orotidine-5'-monophosphate decarboxylase

The pyrG gene of the fungus Blakeslea trispora, encoding orotidine-5'-monophosphate decarboxylase (OMPD) enzyme, was cloned by heterologous hybridization of a genomic library with the Mucor circinelloides pyrG gene. The deduced amino acid sequence of the B. trispora pyrG gene is highly similar to the OMPD from other organisms. Hybridization analyses revealed that the only copy of this gene present in the genome of B. trispora is constitutively expressed. Heterologous complementation of a mutant of M. circinelloides deficient in OMPD activity with the B. trispora pyrG gene and promoter sequence confirmed the function of this gene. This functional complementation demonstrates that heterologous expression in M. circinelloides might be used to investigate the function of genes of B. trispora.