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PubMed1990

Purification, properties and recognition sequence and cleavage site determinations of restriction endonuclease from Acetobacter pasteurianus IFO 13753 (ApaLI).

A new restriction endonuclease, designated as ApaLI, was purified from cell-free extracts of Acetobacter pasteurianus IFO 13753 by streptomycin treatment, ammonium sulfate fractionation, combined column chromatographies on heparin-Sepharose CL-6B and DEAE-Sepharose CL-6B and Fast Protein Liquid Chromatography on Mono Q HR 5/5. The purified enzyme was homogeneous on polyacrylamide gel disc electrophoresis. The molecular weight of the purified enzyme was calculated as 26,000 daltons by gel filtration using Sephadex G-200, and the isoelectric point of the purified enzyme was 4.8 by ampholine sucrose-density gradient isoelectric focusing. The purified enzyme cleaved lambda, Ad2, SV40, M13mp18 RF 1, psi X174 RF I and pBR322 DNAs at 4, 7, 0, 0, 1 and 3 sites, respectively. The purified enzyme worked best at 37 degrees C and pH 8.0 in a reaction mixture (50 microliters) containing 1.0 micrograms lambda DNA, 10mM Tris-HCl, 7 mM 2-mercaptoethanol, 7 mM MgCl2 and 25mM NaCl. However, the purified enzyme did not require NaCl necessarily for the enzyme reaction. The purified enzyme recognized the palindromic hexanucleotide DNA sequence, 5'-GTGCAC-3' and cut between G and T, producing a 5'-cohesive tetranucleotide extension.

Acetobacter↗

PubMed1990

Purification of restriction endonuclease from Acetobacter aceti IFO 3281 (AatII) and its properties.

The restriction endonuclease AatII was purified from cell-free extracts of Acetobacter aceti IFO 3281 by streptomycin treatment, ammonium sulfate fractionation, combined column chromatographies on DEAE-Toyopearl 650S, heparin-Sepharose CL-6B and DEAE-Sepharose CL-6B and FPLC on Mono Q and on Superose 12 (gel filtration). The purified enzyme was homogeneous on SDS-polyacrylamide gel disk electrophoresis. The relative molecular mass of the purified enzyme was 190,000 daltons by gel filtration. The SDS-polyacrylamide gel disk electrophoresis gave the relative molecular mass of 47,500 daltons. These data indicated that the purified, native enzyme is a tetramer (190,000 daltons) composed of four 47,500-dalton subunits. The isoelectric point of the enzyme was 6.0. The purified enzyme was intensely activated by manganese ion (50-fold increase or more when compared with magnesium ion). The enzyme worked best at 37 degrees C and pH 8.5 in a reaction mixture (50 microliters) containing 1.0 micrograms lambda DNA, 10 mM Tris-HCl, 7 mM 2-mercaptoethanol, 7 mM MnCl2 and 50 mM NaCl. The enzyme recognizes the same palindromic hexanucleotide sequence 5'-GACGTC-3', cuts between T and C and produces a 3'-tetranucleotide extension in the presence of MnCl2, as it does in the presence of MgCl2.

Acetobacter↗

PubMedDate not supplied

[Method of determination of the activity of glycerol dehydrogenase in the submerged culture of Acetobacter suboxydans].

The paper presents a method for assaying activity of glycerol dehydrogenase activity in the submerged culture of Acetobacter suboxydans. The effect of substrate concentration, content of the submerged culture in the reaction mixture and pH value on the rate of enzymic oxidation of glycerol to dihygrooxyacetone by A. suboxydans has been studied.

Acetobacter↗

PubMed1985

Effects of detergents and phospholipids on the pyridine nucleotide-independent aldehyde dehydrogenase from membranes of Acetobacter rancens.

The pyridine nucleotide-independent aldehyde dehydrogenase solubilized and purified from membranes of Acetobacter rancens CCM 1774 requires the presence of detergents for activity. While several detergents could stimulate the enzyme activity the stability of the enzyme-detergent complexes was rather low. Phospholipid substitution experiments revealed the reversibility of the loss of activity caused by phospholipid removal. Enzyme-phospholipid complexes generated from a complex phospholipid fraction exhibited an increased stability. The predominant effect of phosphatidylglycerol on both enzyme activity and stability is discussed in terms of essential boundary layer phospholipids.

Acetobacter↗

PubMed1999

Substitution of Asp-309 by Asn in the Arg-Asp-Pro (RDP) motif of Acetobacter diazotrophicus levansucrase affects sucrose hydrolysis, but not enzyme specificity.

beta-Fructofuranosidases share a conserved aspartic acid-containing motif (Arg-Asp-Pro; RDP) which is absent from alpha-glucopyranosidases. The role of Asp-309 located in the RDP motif of levansucrase (EC 2.4.1.10) from Acetobacter diazotrophicus SRT4 was studied by site-directed mutagenesis. Substitution of Asp-309 by Asn did not affect enzyme secretion. The kcat of the mutant levansucrase was reduced 75-fold, but its Km was similar to that of the wild-type enzyme, indicating that Asp-309 plays a major role in catalysis. The two levansucrases showed optimal activity at pH 5.0 and yielded similar product profiles. Thus the mutation D309N affected the efficiency of sucrose hydrolysis, but not the enzyme specificity. Since the RDP motif is present in a conserved position in fructosyltransferases, invertases, levanases, inulinases and sucrose-6-phosphate hydrolases, it is likely to have a common functional role in beta-fructofuranosidases.

Acetobacter↗

PubMed2000

Bacterial cellulose production by Acetobacter xylinum in a 50-L internal-loop airlift reactor.

Bacterial cellulose (BC) production was realized in a batch cultivation of Acetobacter xylinum subsp. sucrofermentans BPR2001 in a 50-L internal-loop airlift reactor. When the bacterium was cultivated with air supply, 3.8 g/L of BC was produced after 67 hours. When oxygen-enriched gas was supplied, the concentration of BC was doubled and the production rate of BC was 0.116 g/L. h, which was two times higher than that of air-supplied culture and comparable to that in a mechanically agitated stirred-tank fermentor. Bacterial cellulose produced by the airlift reactor formed a unique ellipse pellet (BC pellet), different from the fibrous form which was produced in an agitated stirred-tank fermentor. The BC-pellet suspension was demonstrated to have a higher volumetric oxygen transfer coefficient than the fibrous BC suspension in a 50-L internal-loop airlift reactor. The mixing time of BC-pellet suspension in the airlift reactor was also shorter than that in water.

Air↗

PubMed2006

Structural characterization of the Acetobacter xylinum endo-beta-1,4-glucanase CMCax required for cellulose biosynthesis.

Previous studies have demonstrated that endoglucanase is required for cellulose biosynthesis both in bacteria and plants. However, it has yet to be elucidated how the endoglucanases function in the mechanism of cellulose biosynthesis. Here we describe the crystal structure of the cellulose biosynthesis-related endo-beta-1,47-glucanase (CMCax; EC 3.2.1.4) from the cellulose-producing Gramnegative bacterium, Acetobacter xylinum (= Gluconacetobacter xylinus), determined at 1.65-A resolution. CMCax falls into the glycoside hydrolase family 8 (GH-8), and the structure showed that the overall fold of the CMCax is similar to those of other glycoside hydrolases belonging to GH-8. Structure comparison with Clostridium thermocellum CelA, the best characterized GH-8 endoglucanase, revealed that sugar recognition subsite +3 is completely missing in CMCax. The absence of the subsite +3 leads to significant broadness of the cleft at the cellooligosaccharide reducing-end side. CMCax is known to be a secreted enzyme and is present in the culture medium. However, electron microscopic analysis using immunostaining clearly demonstrated that a portion of CMCax is localized to the cell surface, suggesting a link with other known membrane-anchored endoglucanases that are required for cellulose biosynthesis.

Amino Acid Sequence↗

PubMed1991

Identification of a new gene in an operon for cellulose biosynthesis in Acetobacter xylinum.

DNA sequencing of the region downstream of the cellulose synthase catalytic subunit gene of Acetobacter xylinum led to the identification of an open reading frame coding for a polypeptide of 86 kDa. The deduced amino acid sequence of this polypeptide matches from position 27 to 40 with the N-terminal amino acid sequence determined for a 93 kDa polypeptide that copurifies with the cellulose synthase catalytic subunit during purification of cellulose synthase. The cellulose synthase catalytic subunit gene and the gene encoding the 93 kDa polypeptide, along with other genes probably, are organized as an operon for cellulose biosynthesis in which the first gene is the catalytic subunit gene and the second gene codes for the 93 kDa polypeptide. The function of the 93 kDa polypeptide is not clear at present, however it appears to be tightly associated with the cellulose synthase catalytic subunit. Sequence analysis of the polypeptide shows that it is a membrane protein with a signal sequence at the N-terminal end and a transmembrane helix in the C-terminal region for anchoring it into the membrane.

Amino Acid Sequence↗

PubMed1990

Cloning and sequencing of the cellulose synthase catalytic subunit gene of Acetobacter xylinum.

The gene for the catalytic subunit of cellulose synthase from Acetobacter xylinum has been cloned by using an oligonucleotide probe designed from the N-terminal amino acid sequence of the catalytic subunit (an 83 kDa polypeptide) of the cellulose synthase purified from trypsin-treated membranes of A. xylinum. The gene was located on a 9.5 kb Hind III fragment of A. xylinum DNA that was cloned in the plasmid pUC18. DNA sequencing of approximately 3 kb of the Hind III fragment led to the identification of an open reading frame of 2169 base pairs coding for a polypeptide of 80 kDa. Fifteen amino acids in the N-terminal region (positions 6 to 20) of the amino acid sequence, deduced from the DNA sequence, match with the N-terminal amino acid sequence obtained for the 83 kDa polypeptide, confirming that the DNA sequence cloned codes for the catalytic subunit of cellulose synthase which transfers glucose from UDP-glucose to the growing glucan chain. Trypsin treatment of membranes during purification of the 83 kDa polypeptide cleaved the first 5 amino acids at the N-terminal end of this polypeptide as observed from the deduced amino acid sequence, and also from sequencing of the 83 kDa polypeptide purified from membranes that were not treated with trypsin. Sequence analysis suggests that the cellulose synthase catalytic subunit is an integral membrane protein with 6 transmembrane segments. There is no signal sequence and it is postulated that the protein is anchored in the membrane at the N-terminal end by a single hydrophobic helix. Two potential N-glycosylation sites are predicted from the sequence analysis, and this is in agreement with the earlier observations that the 83 kDa polypeptide is a glycoprotein. The cloned gene is conserved among a number of A. xylinum strains, as determined by Southern hybridization.

Amino Acid Sequence↗

PubMed1994

Cloning of the Acetobacter xylinum cellulase gene and its expression in Escherichia coli and Zymomonas mobilis.

A DNA fragment corresponding to carboxymethylcellulase activity of Acetobacter xylinum IFO 3288 was isolated and cloned in Escherichia coli, and the DNA sequence was determined. The DNA fragment sequenced had an open-reading frame of 654 base pairs that encoded a protein of 218 amino acid residues with a deduced molecular mass of 23,996 Da. The protein encoded in the DNA fragment expressed in E. coli hydrolyzed a carboxymethylcellulose. This gene was subcloned into the shuttle vector [pZA22; Misawa et al. (1986) Agric Biol Chem 50:3201-3203] between Zymomonas mobilis and E. coli. The recombinant plasmid pZAAC21 was introduced into Z. mobilis IFO 13756 by electroporation. The carboxymethylcellulase gene was efficiently expressed in both bacteria, although the level of expression in Z. mobilis was ten times greater than that in E. coli. Approximately 75% of the total carboxymethylcellulase activity detected in Z. mobilis was located in the periplasmic space (outside of the cytoplasmic space). Enzyme activity was not detected in the periplasmic space, but in the cytoplasm of E. coli.

Acinetobacter↗

PubMed1987

The plasmids of Acetobacter xylinum and their interaction with the host chromosome.

Acetobacter xylinum contains a complex system of plasmid DNA molecules. Plasmids of molecular weights or copy numbers different from the original wild-type, are found in different types of mutants. Restriction endonuclease digestion and DNA/DNA hybridization analysis, showed that the plasmids often contained partly, but not completely the same DNA sequences. Two of these plasmid classes were analysed in more detail, and could be shown to differ in size by about 5 kb. Hybridization analysis using cloned DNA fragments as probes, showed that sequences lacking in the smallest plasmid were still present in a DNA fraction co-migrating with linearized chromosomal DNA. In addition, at least part of the DNA in the smallest plasmid was present both in the plasmid and chromosomal DNA fraction. Analysis of a particular strain containing an insertion of transposon Tn1, also indicated the existence of complex interactions between plasmids and chromosomal DNA. Together with experiments on conjugative transfer and curing of the plasmids, the results indicate that at least part of the genetic system of A. xylinum is unusual when compared to that of other genetically characterized bacteria.

Cellulose↗

PubMed1989

Cloning of a gene involved in cellulose biosynthesis in Acetobacter xylinum: complementation of cellulose-negative mutants by the UDPG pyrophosphorylase structural gene.

Three cellulose-negative (Cel-) mutants of Acetobacter xylinum strain ATCC 23768 were complemented by a cloned 2.8 kb DNA fragment from the wild type. Biochemical analysis of the mutants showed that they were deficient in the enzyme uridine 5'-diphosphoglucose (UDPG) pyrophosphorylase. The analysis also showed that the mutants could synthesize beta(1-4)-glucan in vitro from UDPG, but not in vivo from glucose. This result was expected, since UDPG is known to be the precursor for cellulose synthesis in A. xylinum. In order to analyze the function of the cloned gene in more detail, its biological activity in Escherichia coli was studied. These experiments showed that the cloned fragment could be used to complement an E. coli mutant deficient in the structural gene for UDPG pyrophosphorylase. It is therefore clear that the cloned fragment must contain this gene from A. xylinum. This is to our knowledge the first example of the cloning of a gene with a known function in cellulose biosynthesis from any organism, and we suggest the gene be designated celA.

Cellulose↗

PubMed1977

Isolation of alpha-glucan and lipopolysaccharide fractions from Acetobacter xylinum.

A cellular phenol-water extract of Acetobacter xylinum NRC 17007 was fractionated on Sepharose 4 B. The fraction eluting with the void volume consisted to about 95% of glycogen-like material. The lipopolysaccharide fraction was of lower molecular weight and had the following composition (%, w/w): Mannose, 42; glucose, 7; galactose, 3.8; heptose, 2; 2-keto-3-deoxy-octonate, 1.2; glucosamine, 3.3; phosphate, 4.5; total fatty acids, 3.9. Among the fatty acids, 3-hydroxy-tetradecanoic acid was present, and 2-hydroxy-hexadecanoic acid predominated.

Carbohydrates↗

PubMed2000

Natural Endophytic Occurrence of Acetobacter diazotrophicus in Pineapple Plants.

The presence of endophytic Acetobacter diazotrophicus was tested for pineapple plants (Ananas comosus [L.] Merr.) grown in the field. Diazotrophic bacteria were isolated from the inner tissues of surface sterilized roots, stems, and leaves of pineapple plants. Phenotypic tests permitted the selection of presumptive nitrogen-fixing A. diazotrophicus isolates. Restriction fragment length polymorphisms (RFLPs) of small subunit (SSU) rDNA using total DNA digested with endonuclease SphI and with endonuclease NcoI, hybridizations of RNA with an A. diazotrophicus large subunit (LSU) rRNA specific probe, as well as patterns in denaturing protein electrophoresis (SDS-PAGE) and multilocus enzyme tests allowed the identification of A. diazotrophicus isolates. High frequencies of isolation were obtained from propagative buds that had not been nitrogen-fertilized, and lower frequencies from 3-month-old plants that had been nitrogen-fertilized. No isolates were recovered from 5- to 7-month-old nitrogen-fertilized plants. All the A. diazotrophicus isolates recovered from pineapple plants belonged to the multilocus genotype which shows the most extensive distribution among all host species previously analyzed. </hea

Journal Article↗

PubMed2003

Utilization of the buffering capacity of corn steep liquor in bacterial cellulose production by Acetobacter xylinum.

Acetobacter xylinum BPR2001 produces water-insoluble bacterial cellulose (BC). Using a pH sensor for the accurate control of pH, which is one of the most critical factors for efficient BC production, is difficult especially in a baffled shake-flask and an airlift reactor. The buffering capacity of corn steep liquor (CSL) was estimated by measuring beta (buffering capacity) values in advance and was used to maintain the pH within the optimal range during the production of BC. When CSL was added to either a shake-flask, a stirred-tank reactor or an airlift reactor, BC production was almost the same as that in cultivations where pH was controlled manually or by a pH sensor.

Bioreactors↗

PubMed2004

Features of bacterial cellulose synthesis in a mutant generated by disruption of the diguanylate cyclase 1 gene of Acetobacter xylinum BPR 2001.

The diguanylate cyclase 1 (DGC1) (dgc1) gene in Acetobacter xylinum BPR 2001--a bacterial cellulose (BC) producer--was cloned and sequenced, and a DGC1 gene-disrupted mutant, strain DD, was constructed. The production and structural characteristics of the BC formed by DD were compared with those of the parental strain BPR 2001. BC production by DD was almost the same as that by BPR 2001 in static cultivation and in shake flask cultivation. However, in a jar fermentor DD produced about 36% more BC than the parental strain. DD produced suspended particle materials that cannot aggregate owing to their random structural characteristics in static cultivation; more uniformly dispersed BC pellicles and smaller BC pellets are produced on average in a jar fermentor, as reflected by the higher BC production by DD than by the parental strain in a jar fermentor. Micrographs of BC produced by DD revealed that the width of cellulose ribbons assemblies decreased as a result of differences in the ultrastructure and mechanism of formation of BC between the two strains. These results reveal that disruption of the dgc1 gene, which catalyzes synthesis of c-di-GMP (an effector of BC synthase), is not fatal for BC synthesis, although it affects BC structure.

Cellulose↗

PubMed2004

Production of bacterial cellulose by Acetobacter xylinum BPR2001 using molasses medium in a jar fermentor.

Bacterial cellulose (BC) production by Acetobacter xylinum subsp. sucrofermentans BPR2001 using molasses medium was carried out in a jar fermentor. When molasses was subjected to H(2)SO(4)-heat treatment, the maximum BC concentration increased to 76% more than that achieved using untreated molasses, and the specific growth rate increased 2-fold. When the initial sugar concentrations in the H(2)SO(4)-heat treated molasses were varied from 23 g/l to 72 g/l, BC concentration, production rate, and yield were maximum at sugar concentrations of 23 g/l and 37 g/l, and production of by-products, such as polysaccharides and CO(2), was lower than at sugar concentrations of 48 g/l and 72 g/l, indicating that maintaining a lower molasses concentration is essential for efficient BC production in jar fermentors, this being due mainly to the complex nature of molasses. Molasses has a clear advantage over pure sugars as a carbon source from an economic viewpoint.

Bioreactors↗

PubMed1997

Endo-beta-Glucanase from Acetobacter xylinum: Purification andCharacterization

A cellulose-producing acetic acid bacterium,Acetobacter xylinum KU-1, abundantly produces an extracellularendo-beta-glucanase (EC 3.2.1.4) in the culture broth. The enzyme was purifiedto homogeneity by DEAE- and CM- Toyopearl 650M ion-exchange chromatography,Butyl-Toyopearl 650M hydrophobic chromatography, and Toyopearl HW-50 gelfiltration. The purified enzyme showed the maximum activity at pH 5 and50°C: it was stable up to 50°C at pH 5, activated by Co2+, andcompetitively inhibited by Hg2+; the apparentKi was 7 &mgr;M. The molecular weight of the enzyme wasdetermined to be about 39,000 by sodium dodesyl sulfate/polyacrylamide gelelectrophoresis, and about 41,000 by Toyopearl HW-50 gel filtration; theenzyme is monomeric. The enzyme hydrolyzed carboxymethylcellulose with anapparent Km of 30 mg/ml and Vmax of 1.2&mgr;M/min. It hydrolyzed cellohexaose to cellobiose, cellotriose andcellotetraose, and also cellopentaose to cellobiose and cellotriose, but didnot act on cellobiose, cellotriose, or cellotetraose.

Journal Article↗