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At least 631 records · Page 35Linked to original sources
PubMed2002

[Influence of pH control on the production of curdlan by Alcaligenes faecalis strain].

A two-stage pH control method was employed in batch fermentation of curdlan by Alcaligenes faecalis WX-C12 where cell-growth stage was constantly controlled at pH 7.0 and stationary stage was controlled at a constant pH as well. The influence of pH control on the curdlan production was investigated. The optimal pH control of batch process for curdlan production was obtained when cell-growth stage was controlled at pH 7.0 and stationary stage was constantly controlled at pH 5.6. Production and productivity of curdlan, QP and YP/S reached 28.19 g/L, 291 mg/(L.h), 132.27 mg/(L.h.g) and 0.659, an improvement of 20.4%, 38.1%, 38.1% and 29.5% compared to a pH uncontrolled operation respectively.

Alcaligenes↗
PubMed2003

Purification and characterization of Alcaligenes faecalis penicillin G acylase expressed in Bacillus subtilis.

The Alcaligenes faecalis PGA gene encoding heterodimeric penicillin G acylase (PGA) was cloned and successfully expressed in Escherichia coli and Bacillus subtilis respectively. In contrast to E.coli hosts where the enzymes were retained in the periplasm, B. subtilis cell secreted the recombinant enzyme into the medium. Contrary to limited expression yield of E. coli (pETAPGA), PGA extracellularly expressed by B. subtilis (pBAPGA) and B. subtilis (pMAPGA) reached the highest yield of 653 u/L. This yield increased 109-fold higher than the native expression of A. faecalis CICC AS1.767. The enzyme was fractionated with (NH(4))(2)SO(4) and purified by DEAE-Sepharose CL-6B with a yield of 81%. The purified enzyme had a specific activity of 1.469 u/mg. Furthermore, some enzyme characteristics, such as the pH and temperature optimum, the stability against organic solvent and the ratio of cepholexin synthesis to hydrolysis were determined. By overexpressing A. faecalis PGA in B. subtilis and purifying secreted enzyme from culture medium one could readily obtain a large amount of an alternative source of PGA.

Alcaligenes↗
PubMed1992

The importance of Asn47 for structure and reactivity of azurin from Alcaligenes denitrificans as studied by site-directed mutagenesis and spectroscopy.

To study the importance of a rigid copper site for the structure and function of azurin, a mutant with a reduced number of internal hydrogen bonds around the copper has been prepared and characterized. To this purpose, the previously cloned azu gene from Alcaligenes denitrificans (Hoitink, C. W. G., Woudt, L. P., Turenhout, J. C. M., Van de Kamp, M., and Canters, G. W. (1990) Gene (Amst.) 90, 15-20) was expressed in Escherichia coli and an isolation and purification procedure for the azurin was developed. The azurin obtained after heterologous expression in E. coli appears spectroscopically indistinguishable from azurin derived from A. denitrificans. The hydrogen bonding network around the copper site was altered by replacing Asn47 by a leucine by means of site-directed mutagenesis. Asn47 is a conserved residue in all blue copper proteins of which the primary structure has been reported. Characterization of the mutant protein with UV-visible, electron spin resonance, and NMR spectroscopy, and comparison with the wild type azurin revealed that the structure of the copper site as well as the overall structure of the protein have been largely retained. The redox activity as measured by the electron self-exchange rate appears not to have changed either. However, the mutant differs from the wild type azurin with respect to stability and midpoint potential. Midpoint potentials of mutant and wild type azurin amount to 396 and 286 mV, respectively. The difference is due to sizable entropic and enthalpic contributions which to a large extent cancel. Possible explanations for the outcome of these experiments are discussed.

Alcaligenes↗
PubMed1992

The purification and characterization of arsenite oxidase from Alcaligenes faecalis, a molybdenum-containing hydroxylase.

The purification and initial characterization of arsenite oxidase from Alcaligenes faecalis are described. The enzyme consists of a monomer of 85 kDa containing one molybdenum, five or six irons, and inorganic sulfide. In the presence of denaturants arsenite oxidase releases a fluorescent material with spectral properties identical to the pterin cofactor released by the hydroxylase class of molybdenum-containing enzymes. Azurin and a c-type cytochrome, both isolated from A. faecalis, each serves as an electron acceptor to arsenite oxidase and may form a periplasmic electron transfer pathway for arsenite detoxification. Full reduction of arsenite oxidase requires 3-4 reducing equivalents, using either arsenite or dithionite as the electron source. Below 20 K, oxidized arsenite oxidase exhibits an EPR signal with g values of 2.03, 2.01, and 2.00, which integrates to approximately 0.4 spins/protein. Since enrichment in 57Fe results in broadening of this EPR signal, the center giving rise to this signal must contain iron. The most plausible candidates are a [4Fe-4S] high potential iron protein center or a [3Fe-4S] center. The EPR signal observed in oxidized arsenite oxidase disappears upon reduction of the protein with either arsenite or dithionite. Concomitantly, a rhombic EPR signal (g = 2.03, 1.89, 1.76) appears which is similar to that of Rieske-type [2Fe-2S] clusters and spin quantifies to one spin/protein.

Alcaligenes↗
PubMed1991

The disruption of Alcaligenes eutrophus by high pressure homogenisation: key factors involved in the process.

The disruption of the Gram-negative bacterium Alcaligenes eutrophus by high pressure homogenisation, using the APV Gaulin 15M 8BA and 30CD homogenisers is reported. The operating parameters such as operating pressure, number of passes, temperature and biomass concentration, mimicked trends previously reported for yeasts. Extension of the study to consider the effect of cell characteristics, including the growth rate, size and shape, illustrated the dominant effect of the growth phase. The improved disruption of bacterial cultures in the logarithmic phase with respect to stationary phase cultures was confirmed by an increased dependence of actively growing cultures on the operating pressure. An increase in size in excess of 30% on the accumulation of the storage product, PHB in the stationary phase caused little change in the ease of disruption. The use of transmission electron microscopy to directly monitor the disruption on multiple passes shed light on the two-stage nature of this disruption process.

Alcaligenes↗
PubMed1992

[The construction of genomic library of Alcaligenes faecalis and cloning of nifH gene sequence homologous to Klebsiella pneumoniae].

A genomic library of Alcaligenes faecalis A-15Hl which possesses rather high nitrogenase activity has been constructed. The total DNA of A. faecalis A-15 Hl was partially digested with Sau3AI. 13-20 kb of fragments recovered from agarose gel were cloned in bacteriophage EM-BL4 vector. A total number of 1.2 x 10(6) of recombinants was obtained. It is much beyond the desired capacity of a library. By using nifH gene of K. pneumoniae from plasmid pGB1 as probe, we have successfully screened the clone containing its homologous sequence. The recombinant bacteriophage DNA was digested with EcoRI. A 3.5 kb of hybridizing band appeared after southern blotting and then was cloned in pUC19 DNA. The result of southern blotting indicated that the recombinant plasmid clone contained nifH gene sequence of A. faecalis. This clone was named as pAFH.

Alcaligenes↗
PubMed1992

Five cases of Alcaligenes pseudobacteraemia.

A cluster of five cases of pseudobacteraemia due to the organism Alcaligenes denitrificans occurred in three hospital medical wards over a four week period. The same organism was isolated from four of twelve commercially prepared bottles for erythrocyte sedimentation tests. The most likely explanation for the outbreak is that the ESR bottles were filled prior to inoculation of blood culture bottles. The outbreak was brought to an end by advising on correct procedure.

Alcaligenes↗
PubMed1992

[Characterization of Alcaligenes species using analysis of esterase electrophoretic polymorphism and analysis of antibiotic resistance profiles].

The species of an Alcaligenes bacterial strain may be difficult to determine on the basis of conventional phenotype features. Esterase pattern analysis using acrylamide-agar gel electrophoresis and determination of the antimicrobial resistance profile (agar diffusion method) were performed for A. faecalis (34 strains). A. denitrificans subsp xylosoxydans (16 strains) and A. piechaudi (5 strains). The Cistat program (D2 Software) was used for statistical representation of results. The homogeneous, species-specific esterase patterns ensured correct assignment of each strain to one of the three species. Antimicrobial susceptibility was greatest for A. faecalis which was susceptible to both cephalosporins of all generations and aminoglycosides. A. xylosoxydans was the species with the greatest resistance to antimicrobials. A. piechaudii exhibited intermediate susceptibility.

Alcaligenes↗
PubMed2003

Biological control of Fusarium wilt of pigeonpea Cajanus cajan (L.) Millsp with chitinolytic Alcaligenes xylosoxydans.

Alcaligenes xylosoxydans protected pigeonpea from Fusarium wilt in a pot experiment and field trials. When seeds of pigeonpea (C. cajan) were treated with A. xylosoxydans and sown in soil infested with Fusarium, the incidence of wilt was reduced by 43.5% and resulted in 58% higher grain yield. The antifungal activity of A. xylosoxydans was based on chitinase production and was comparable in efficacy to commercial antifungal agents such as benlate, monitor WP, thiram and bavistin.

Alcaligenes↗
PubMed2004

Enzymatic and non-enzymatic degradation of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) copolyesters produced by Alcaligenes sp. MT-16.

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3HB-co-3HV), copolyesters with a variety of 3HV contents (ranging from 17 to 60 mol%) were produced by Alcaligenes sp. MT-16 grown on a medium containing glucose and levulinic acid in various ratios, and the effects of hydrophilicity and crystallinity on the degradability of the copolyesters were evaluated. Measurements of thermo-mechanical properties and Fourier-transform infrared spectroscopy in the attenuated total reflectance revealed that the hydrophilicity and crystallinity of poly(3HB-co-3HV) copolyesters decreased as 3HV content in the copolyester increased. When the prepared copolyester film samples were non-enzymatically hydrolysed in 0.01 N NaOH solution, the weights of all samples were found to have undergone no changes over a period of 20 weeks. In contrast, the copolyester film samples were degraded by the action of extracellular polyhydroxybutyrate depolymerase from Emericellopsis minima W2. The overall rate of weight loss was higher in the films containing higher amounts of 3HV, suggesting that the enzymatic degradation of the copolyester is more dependent on the crystallinity of the copolyester than on its hydrophilicity. Our results suggest that the degradability characteristics of poly(3HB-co-3HV) copolyesters, as well as their thermo-mechanical properties, are greatly influenced by the 3HV content in the copolyesters.

Acyltransferases↗
PubMed2005

Alcaligenes xylosoxidans bacteremia: clinical features and microbiological characteristics of isolates.

Bacteremia caused by Alcaligenes xylosoxidans is rare. Between 1999 and 2002, 12 cases of bacteremia caused by A. xylosoxidans were diagnosed at a tertiary referral center in central Taiwan. The clinical features of these patients and the antimicrobial susceptibilities and pulsed-field gel electrophoresis (PFGE) pattern of their blood isolates were studied. All infections were acquired nosocomially. All of the adult patients had underlying diseases, and 10 (83%) had undergone an invasive procedure. The clinical syndrome included primary bacteremia in 7 patients (58%), and catheter-associated bacteremia, surgical wound infection, pneumonia, urinary tract infection, and empyema in 1 each. Polymicrobial bacteremia was found in 1 patient. The case-fatality rate was 17% (2/12). All isolates were susceptible to piperacillin and ceftazidime and resistant to aminoglycoside, ciprofloxacin and cefepime. Susceptibility to imipenem (67%), ampicillin-sulbactam (75%) and trimethoprim-sulfamethoxazole (92%) was variable. Genetic fingerprints obtained by PFGE showed identical pattern in the isolates from 2 neonates, indicating the epidemiologic relatedness of these infections. We conclude that A. xylosoxidans isolates are multi-resistant and A. xylosoxidans bacteremia should be considered as a possible etiology of infection after invasive procedures in patients with underlying diseases. Strict infection control is needed to prevent this infection.

Adult↗
PubMed2005

Alcaligenes faecalis kw-a biofilm for denitrification of nitrate-rich effluent.

Alcaligenes faecalis kw-A selected for possessing good denitrification efficiency was used for biofilm development. The biofilm could be developed on a glass surface within 12 hr when 5%, Ix 10(8) cells/ml was used as inoculum. The microcolonies were seen in 6 hr and glycocalyx in 9 hr stage. At 24 hr the biofilm was developed fully and hence was visualised as dense mass. The biofilm protein content showed 48.5% increase in shake flask than in static condition. The exopoplymer is produced in larger amounts in biofilm as compared to the suspended cells. Also, its amount was more by 43% in the biofilm produced in shake flask condition than in static condition. The biofilm could remove 95% nitrate from nitrate-rich effluent in a bench-scale process in 36 hr. The attached growth technique demonstrated here can be utilised to study the effect of favourable as well as adverse conditions on the denitrification efficiency of a culture. The ultimate application of a denitrifying biofilm would be in attached growth or biofilm reactor.

Alcaligenes faecalis↗
PubMed1975

[Denitrifying bacteria of genus Alcaligenes isolated from soil].

The organism isolated is a small non-sporulating Gram-negative rod, motile by means of peritrichous flagellae. It is an oxidase-positive chemo-organotroph utilizing O2,NO-3,NO-2 and N2O as resiratory substrates. Primary alcohols as well as numerous organic and amino acids are utilized as carbon and energy sources. Carbohydrates are not assimilated. Poly-beta-hydroxybutyrate is accumulated intracellularly. The bacterium is assigned to the genus Alcaligenes and its phenotype characteristics are compared with those of A. faecalis.

Alcaligenes↗
PubMed1991

Cloning, nucleotide sequence, and heterologous expression of a high-affinity nickel transport gene from Alcaligenes eutrophus.

High-affinity nickel transport in Alcaligenes eutrophus H16 is mediated by a function designated hoxN. hoxN lies within the hydrogenase gene cluster of megaplasmid pHG1. An insertional mutation at the hoxN locus led to an increased nickel requirement. In this mutant (strain HF260) both autotrophic growth on hydrogen and wild-type level of urease, a nickel-containing enzyme, were dependent on high concentration of nickel in the medium. Studies with a heterologous in vivo expression system revealed that the hoxN locus encodes two proteins with Mr = 30,000 and 28,000. Only the larger polypeptide was essential for nickel transport. The hoxN locus was cloned on a 2.2-kilobase pair fragment. Nucleotide sequence analysis of the hoxN locus revealed an open reading frame with a coding capacity for a protein of 33.1 kDa. The insertion leading to the Nic- phenotype of strain HF260 maps within this open reading frame indicating that it does in fact have coding function. The deduced amino acid sequence of the hoxN gene has several features typical of a hydrophobic integral membrane protein. Alkaline phosphatase fusion proteins produced by insertion of the transposon TnphoA into hoxN gave significant levels of alkaline phosphatase activity indicating that protein HoxN contains periplasmic domains. Taken together, our results suggest that gene hoxN encodes the high-affinity nickel transporter of A. eutrophus.

Alcaligenes↗
PubMed1990

Nucleotide sequence and expression of a plasmid-encoded chromate resistance determinant from Alcaligenes eutrophus.

The nucleotide sequence of the 2.6-kilobase pair (kb) EcoRI fragment encoding chromate resistance (Chrr) on plasmid pMOL28 in Alcaligenes eutrophus was determined. Three open reading frames were assigned to three polypeptides which were expressed from this determinant in Escherichia coli under the control of a phage T7 transcription promoter. When the roles of the polypeptides and open reading frames were analyzed with deletion derivatives of the 2.6-kilobase fragment, the membrane-bound ChrA (401 amino acids) and ChrB (196 amino acids) polypeptides were essential for inducible chromate resistance and reduced accumulation of chromate, while the third open reading frame was not needed.

Alcaligenes↗
PubMed1990

Purification and characterization of dichloromuconate cycloisomerase from Alcaligenes eutrophus JMP 134.

Dichloromuconate cycloisomerase from Alcaligenes eutrophus JMP 134 was purified to homogeneity. The enzyme has an Mr of about 270,000 as determined by gel filtration and consists of six to eight subunits of identical Mr 40,000 as determined by SDS/PAGE. Mn2+ ions as well as thiol groups are required for activity. A high Km value of about 4 mM for cis,cis-muconate explains the reported low activity with this compound. Relatively high Km values were also calculated for monochloro-substituted cis,cis-muconates (300-500 microM), in contrast with the low Km value of 20 microM for 2,4-dichloro-cis,cis-muconate. The catalytic constant of the pure enzyme was 3820 min-1 when measured with 2,4-dichloro-cis,cis-muconate.

Alcaligenes↗
PubMed1986

[Antigenic polysaccharides of bacteria. 19. The structure of the O-specific polysaccharide chain of Alcaligenes faecalis lipopolysaccharide].

On mild acid hydrolysis of Alcaligenes faecalis lipopolysaccharide, the O-specific polysaccharide containing D-rhamnose and D-xylose in the 3:2 ratio was obtained. Solvolysis of the polysaccharide with hydrogen fluoride in methanol resulted in methyl glycoside of a branched tetrasaccharide including three rhamnose and one xylose residues. Smith degradation of the polysaccharide led to the glycoside of disaccharide composed of two rhamnose residues and glycerol. On the basis of identification of the oligosaccharide fragments, methylation, 1H and 13C NMR analysis (including nuclear Overhauser effect data), it was established that the polysaccharide linear chain is a rhamnan, both xylose residues being attached to one of the rhamnose residues as two branches. The repeating unit of the polysaccharide has the following structure: (Formula: see text).

Alcaligenes↗
PubMed1986

[Physico-chemical properties and heterogeneity of Alcaligenes faecalis polysaccharide].

Two species of O-antigenic molecules with following sedimentation characteristics S(o)20, W 1,25.10(-13) S, D(o)20, W 9,7.10(-7) cm2/s, M 8000 and S(o)20, W 2,5.10(-13) S, D(o)20, W 5.10(-7) cm2/s, M 23,000-30,000 were detected in the cell wall of the strain Alcaligenes faecalis, a representative species of conditionally pathogenic microorganisms with unidentified taxonomic position. "Light" and "heavy" types of molecules have a lipopolysaccharide nature and show no differences in the monosaccharide composition of the polysaccharide moiety, structural organization of O-chain, or lipid A fatty-acid composition.

Alcaligenes↗