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We characterized the pyrroloquinoline quinone (PQQ)-dependent dehydrogenase 9 (PQQ-DH9) of Gluconobacter sp. strain CHM43, which is a homolog of PQQ-dependent glycerol dehydrogenase (GLDH). We used a plasmid construct to express PQQ-DH9. The expression host was a derivative strain of CHM43, which lacked the genes for GLDH and the membrane-bound alcohol dehydrogenase and consequently had minimal ability to oxidize primary and secondary alcohols. The membranes of the transformant exhibited considerable d -arabitol dehydrogenase activity, whereas the reference strain did not, even if it had PQQ-DH9-encoding genes in the chromosome and harbored the empty vector. This suggests that PQQ-DH9 is not expressed in the genome. The activities of the membranes containing PQQ-DH9 and GLDH suggested that similar to GLDH, PQQ-DH9 oxidized a wide variety of secondary alcohols but had higher Michaelis constants than GLDH with regard to linear substrates such as glycerol. Cyclic substrates such as cis -1,2-cyclohexanediol were readily oxidized by PQQ-DH9. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

A novel oxidation of D-pentonates to 4-keto-D-pentonates was analyzed withGluconobacter thailandicusNBRC 3258. D-Pentonate 4-dehydrogenase activity in the membrane fraction was readily inactivated by EDTA and it was reactivated by the addition of PQQ and Ca2+. D-Pentonate 4-dehydrogenase was purified to two different subunits, 80 and 14 kDa. The absorption spectrum of the purified enzyme showed no typical absorbance over the visible regions. The enzyme oxidized D-pentonates to 4-keto-D-pentonates at the optimum pH of 4.0. In addition, the enzyme oxidized D-fructose to 5-keto-D-fructose, D-psicose to 5-keto-D-psicose, including the other polyols such as, glycerol, D-ribitol, D-arabitol, and D-sorbitol. Thus, D-pentonate 4-dehydrogenase was found to be identical with glycerol dehydrogenase (GLDH), a major polyol dehydrogenase inGluconobacterspecies. The reaction versatility of quinoprotein GLDH was notified in this study. [ABSTRACT FROM AUTHOR]

The article presents a study that attempts to identify the genes essential for growth at high temperature by transposon (Tn10) mutagenesis to elucidate the mechanism underlying the thermotolerance of mesophilic strains. It states that Acetobacter tropicalis SKU1100 is a thermotolerant acetic acid bacterium that dwells even at high temperatures. Results have further supported the partial overlap between the genes required for acetic acid resistance and those needed for thermotolerance.

The article presents a study on the production of 5-keto-D-gluconate (5KGA) derived from D-glucose by Gluconobacter. The study indicates that the effect of potential of hydrogen (pH) is essential in the production of 5KGA is correlative with the pH dependency of 5KGA. It notes that the 5KGA compound holds potential as an intermediate in the food industry.

The article focuses on the production of 4-keto-D-arabonate (4KAB) by Gluconacetobacter liquefaciens strains. It states that the strains accumulated 2,5-diketo-d-gluconate (25DKA) and oxidized D-gluconate, D-glucose, and 2-keto-D-gluconate (2KGA). It says that after the accumulation, 25DKA was converted into 4KAB and 4KAB remained stable in Gluconacetobacter liquefaciens. Moreover, a study of M. Ameyama and K. Kondo on carbohydrate metabolism of acetic acid bacteria assumed the 4KAB occurrence.

The article presents a study regarding the productiuon of 3-dehydroshikimate (DSA) from quinate by immobilixing the membrane fraction of the acetic acid bacteria Gluconobacter oxydans IFO 3244. The study used several methods to realize and examine the immobilization process including encapsulation, ionic binding, and physical adsorption. Results show a conversion rate of almost 100% from quinate to 3-dehydroshikimate.

The article presents a study concerning acetic acid fermentation of Acetobacter pasteurianus. The study involves the examination of the relationship between pellicle polysaccharide formation and acetic acid resistance. It shows that acetic acid resistance ability pellicle formation is primarily related to pellicle formation, thus is essential to acetic acid fermentation in A. pasteurianus strains.

The article presents a study that focuses on the purification and characterization of the membrane-bound 3-dehydroshikimate dehydratase (mDSD) and enzyme solubilization from the membrane fraction of gluconobacter oxydans IFO 3244. The results revealed that the mDSD in the membrane fraction suggests the mDSD's significance of aromatization, solubilized and purified to high homogeneity. It says that dehydroshikimate (DSA) was confirmed as a direct precursor of phenylcyclohexylamine (PCA).

The article discusses membrane-bound glucono-δ-lactonase (MGL) properties, solubility, and enzyme purification. It presents the process wherein MGL is purified from Gluconobacter oxydans. It also discusses that the involved acetic acid bacteria and aerobic bacteria in the oxidative fermentation contains a well-developed periplasmic oxydase system which yields bioenergy formation.

The article studies tightly-bound quinone functions in the ubiquinone reaction sites of the quinoprotein alcohol dehydrogenase (ADH) of the Gluconobacter suboxydans bacterium in acetic acid. It includes an in-depth analysis of the solubilization and purification of ADH with dodecyl maltoside, as well as a discussion on the issues' implications for biological chemistry.

The article presents a study which examines the purification and properties of dihydroxyacetone (DHA) reductases in gluconobacter suboxydans grown in gycerol. It states that two DHA reductases were detected in the same cytoplasm gluconobacter suboxydans. It notes that NADH-dependent appears inducible and labile in nature while the NADPH-dependent appears constitutive and stable. It also notes that the two DHARS were specific only to DHA reduction to glycerol.

The article reports on a study on the novel 3-dehydroquinate dehydrase (DQD) catalyzing extracellular formation of 3-dehydroshikimate by oxidative fermentation of Gluconobacter oxydans IFO 3244. The study showed that the same apparent molecular weights and same catalytic properties, but they were distinct from each other in subunit molecular mass.

The article discusses a study which investigated the energy metabolism and respiratory chain of Asaia bogorensis. A. bogorensis is a unique acetic acid bacterium with unusual properties including scanty acetic acid production and rapid growth. The found that A. bogorensis lacks quinoprotein alcohol dehydrogenase, but has sugar and sugar alcohol-oxidizing enzymes specific to the respiratory chain of Gluconobacter.

The article reports on the results of a study of the occurrence of a novel NADH dehydrogenase (NADH-dh), distinct from the old yellow enzyme, in gluconobacter strains A description of the experimental set-up and measurement methods is presented. The study concluded that the N-terminal amino acid sequence of NADPH-dh matched a putative oxidoreductase containing the old yellow enzyme-like FMN-binding domain.

The article discusses the study about the conversion of capsular polysaccharide (CPS) to extracellular polysaccharide (EPS) by galE deletion in acetobacter tropicalis. A clone of the galE gene from Acetobacter tropicalis was performed. Results show that the cloned gene does not produce CPS, but secreted an EPS, which is purified and having a unique characteristic from the original CPS.

The article discusses the results of a study which examined membrane-bound NAD(P)-independent formaldehyde-oxidizing enzyme from Acetobacter sp. SKU 14. The enzyme was solubilized from the membrane fraction of glycerol-grown cells and was purified to homogeneity through column chromatographies. The purified enzyme was characterized as a quinoprotein alcohol dehydrogenase.

Examines the molecular properties of membrane-bound FAD-containing D-sorbitol dehydrogenase (SLDH) from thermotolerant Gluconobacter frateurii, an acetic acid bacteria. Industrial application of Gluconobacter strains; Role of SLDH in L-sorbose fermentation; Method used for the purification of FAD-SLDH from Gluconobacter frateurii.

Acetic acid bacteria are gram-negative obligate aerobic bacteria assigned to the family Acetobacteraceae of Alphaproteobacteria . They are members of the genera Acetobacter , Gluconobacter , Gluconacetobacter , Acidomonas , Asaia , Kozakia , Swaminathania , Saccharibacter , Neoasaia , Granulibacter , Tanticharoenia , Ameyamaea , Neokomagataea , and Komagataeibacter . Many strains of Acetobacter and Komagataeibacter have been known to possess high acetic acid fermentation ability as well as the acetic acid and ethanol resistance, which are considered to be useful features for industrial production of acetic acid and vinegar, the commercial product. On the other hand, Gluconobacter strains have the ability to perform oxidative fermentation of various sugars, sugar alcohols, and sugar acids leading to the formation of several valuable products. Thermotolerant strains of acetic acid bacteria were isolated in order to serve as the new strains of choice for industrial fermentations, in which the cooling costs for maintaining optimum growth and production temperature in the fermentation vessels could be significantly reduced. Genetic modifications by adaptation and genetic engineering were also applied to improve their properties, such as productivity and heat resistance. [ABSTRACT FROM AUTHOR]

Quino(hemo)protein alcohol dehydrogenases (ADH) that have pyrroloquinoline quinone (PQQ) as the prosthetic group are classified into 3 groups, types I, II, and III. Type I ADH is a simple quinoprotein having PQQ as the only prosthetic group, while type II and type III ADHs are quinohemoprotein having heme c as well as PQQ in the catalytic polypeptide. Type II ADH is a soluble periplasmic enzyme and is widely distributed in Proteobacteria such as Pseudomonas, Ralstonia, Comamonas, etc. In contrast, type III ADH is a membrane-bound enzyme working on the periplasmic surface solely in acetic acid bacteria. It consists of three subunits that comprise a quinohemoprotein catalytic subunit, a triheme cytochrome c subunit, and a third subunit of unknown function. The catalytic subunits of all the quino(hemo)protein ADHs have a common structural motif, a quinoprotein-specific superbarrel domain, where PQQ is deeply embedded in the center. In addition, in the type II and type III ADHs this subunit contains a unique heme c domain. Various type II ADHs each have a unique substrate specificity, accepting a wide variety of alcohols, as is discussed on the basis of recent X-ray crystallographic analyses. Electron transfer within both type II and III ADHs is discussed in terms of the intramolecular reaction from PQQ to heme c and also from heme to heme, and in terms of the intermolecular reaction with azurin and ubiquinone, respectively. Unique physiological functions of both types of quinohemoprotein ADHs are also discussed. [Copyright &y& Elsevier]

The bacterial aerobic respiratory chain has a terminal oxidase of the heme-copper oxidase superfamily, comprised of cytochrome c oxidase (COX) and ubiquinol oxidase (UOX); UOX evolved from COX. Acetobacter pasteurianus , an α-Proteobacterial acetic acid bacterium (AAB), produces UOX but not COX, although it has a partial COX gene cluster, ctaBD and ctaA , in addition to the UOX operon cyaBACD . We expressed ctaB and ctaA genes of A. pasteurianus in Escherichia coli and demonstrated their function as heme O and heme A synthases. We also found that the absence of ctaD function is likely due to accumulated mutations. These COX genes are closely related to other α-Proteobacterial COX proteins. However, the UOX operons of AAB are closely related to those of the β/γ-Proteobacteria (γ-type UOX), distinct from the α/β-Proteobacterial proteins (α-type UOX), but different from the other γ-type UOX proteins by the absence of the cyoE heme O synthase. Thus, we suggest that A. pasteurianus has a functional γ-type UOX but has lost the COX genes, with the exception of ctaB and ctaA , which supply the heme O and A moieties for UOX. Our results suggest that, in AAB, COX was replaced by β/γ-Proteobacterial UOX via horizontal gene transfer, while the COX genes, except for the heme O/A synthase genes, were lost. [ABSTRACT FROM AUTHOR]

Formaldehyde elimination was successfully carried out with Acetobacter sp. SKU 14, having strong formaldehyde-oxidizing activity in the cytoplasmic membrane. Formaldehyde was decomposed via formate to carbon dioxide by formaldehyde- and formate-oxidizing activities. A resting-cell suspension of the organism was more convenient for practical purposes than the isolated membrane fraction. In Gluconobacter suboxydans IFO 12528, formaldehyde elimination was not so prominent when compared with that in Acetobacter sp. SKU 14. [Copyright &y& Elsevier]

Acetobacter aceti IFO 3284 has been shown to have two types of strains: one forms a smooth-surfaced colony (S strain) and the other forms a rough-surfaced colony (R strain) (Matsushita et al., 1992). In this study, both S and R strains were isolated and characterized. The S strain grew well in submerged culture but very poorly in static culture. In contrast, the R strain grew well in static culture by floating on the surface of the culture medium, as well as in shaking submerged culture. Scanning electron microscopy revealed that the R strain was covered by some amorphous materials that were not seen in the S strain. The R strain produced 5-fold higher levels of sugars related to polysaccharides responsible for pellicle formation than the S strain did. Unlike cellulose of Acetobacter xylinum, the polysaccharides of the R strain were cellulase-resistant and alkaline-sensitive. The polysaccharides were not secreted into the culture medium, and more than 90% of them were retained in the membrane fraction when the cells were disrupted under mild conditions by lysozyme treatment. Furthermore, the polysaccharides were shown to be mainly attached to the outer membrane when separated. After solubilization with β-octylglucoside, the membrane-attached polysaccharides were purified by several steps including enzyme treatment, column chromatography and alcohol precipitation. The purified polysaccharide was estimated to have an apparent molecular mass of 700-kDa based on Sephacryl S-500 column chromatography, and to be composed of two monosaccharides, glucose and rhamnose, at an approximately equimolar ratio. Thus, in this study, we clarified that the A. aceti R strain produced a polysaccharide associated with the flotation of the cells on the medium surface, like A. xylinum, and that the polysaccharide was a novel one consisting of glucose and rhamnose. [Copyright &y& Elsevier]

• Sorbosone dehydrogenase (SNDH) of Gluconacetobacter liquefaciens was characterized. • The SNDH activity is dependent on pyrroloquinoline quinone (PQQ). • Natural electron acceptor for SNDH is most likely membranous ubiquinone. • A structure was modeled with soluble PQQ-dependent pyranose dehydrogenase in silico. Membrane-bound sorbosone dehydrogenase (SNDH) of Gluconacetobacter liquefaciens oxidizes l -sorbosone to 2-keto- l -gulonic acid (2KGLA), a key intermediate in vitamin C production. We constructed recombinant Escherichia coli and Gluconobacter strains harboring plasmids carrying the sndh gene from Ga. liquefaciens strain RCTMR10 to identify the prosthetic group of SNDH. The membranes of the recombinant E. coli showed l -sorbosone oxidation activity, only after the holo-enzyme formation with pyrroloquinoline quinone (PQQ), indicating that SNDH is a PQQ-dependent enzyme. The sorbosone-oxidizing respiratory chain was thus heterologously reconstituted in the E. coli membranes. The membranes that contained SNDH showed the activity of sorbosone:ubiquinone analogue oxidoreductase. These results suggest that the natural electron acceptor for SNDH is membranous ubiquinone, and it functions as the primary dehydrogenase in the sorbosone oxidation respiratory chain in Ga. liquefaciens. A biotransformation experiment showed l -sorbosone oxidation to 2KGLA in a nearly quantitative manner. Phylogenetic analysis for prokaryotic SNDH homologues revealed that they are found only in the Proteobacteria phylum and those of the Acetobacteraceae family are clustered in a group where all members possess a transmembrane segment. A three-dimensional structure model of the SNDH constructed with an in silico fold recognition method was similar to the crystal structure of the PQQ-dependent pyranose dehydrogenase from Coprinopsis cinerea. The structural similarity suggests a reaction mechanism under which PQQ participates in l -sorbosone oxidation. [ABSTRACT FROM AUTHOR]