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A novel bacterium, Arthrobacter globiformis DC-1, capable of degrading DDT as its sole carbon and energy source, was isolated from DDT-contaminated agricultural soil. The bacterium can degrade up to 76.3% of the DDT at a concentration of 10 mg/L in the mineral salt medium (MSM) within 1 day of incubation. The effects of various environmental conditions, such as the concentration of DDT, temperature, pH and additional carbon sources, on its growth and biodegrading capacity of DDT were investigated in the MSM. The A. globiformis DC-1 strain could efficiently grow and degrade DDT at a wide range of concentrations, with the maximum growth and degradation rate at 10 mg/LDDT, followed by inhibitory effects at higher concentrations (20 and 30 mg/LDDT). Mesophilic temperatures (25–30 °C) and a pH of 7–7.5 were the most suitable conditions for the growth and biodegradation. The presence of carbon sources significantly increased the growth of the DC-1 strain; however, degradation was inhibited in the present of glucose, sucrose and fructose, and peptone was determined to be the most appropriate carbon source for A. globiformis DC-1. The optimal DDT degradation (84.2%) was observed at 10 mg/LDDT, peptone as carbon source in pH 7.5 at 30 °C with 1 day of incubation. This strain could also degrade DDE, DDD and DDT simultaneously as the sole carbon and energy source, with degradation rates reaching 70.61%, 64.43% and 60.24% in 10 days, respectively. The biodegradation pathway by A. globiformis DC-1 revealed that DDT was converted to DDD and DDE via dechlorination and dehydrochlorination, respectively; subsequently, both DDD and DDE transformed to DDMU through further dechlorination, and finally, after ring opening, DDMU was mineralized to carbon dioxide. No intermediate metabolites accumulation was observed during the GC/MS analysis, demonstrating that the A. globiformis DC-1 strain can be used for the bioremediation of DDT residues in the environment. [ABSTRACT FROM AUTHOR]

Dextran α-1,2-debranching enzyme (DDE) releases glucose with hydrolyzing α-(l→2)-glucosidic linkages in α-glucans, which are made up of dextran with α-(1→2)-branches and are generated by Leuconostoc bacteria. DDE was isolated from Microbacterium dextranolyticum (formerly known as Flavobacterium sp. M-73) 40 years ago, although the amino acid sequence of the enzyme has not been determined. Herein, we found a gene for this enzyme based on the partial amino acid sequences from native DDE and characterized the recombinant enzyme. DDE had a signal peptide, a glycoside hydrolase family 65 domain, a carbohydrate-binding module family 35 domain, a domain (D-domain) similar to the C-terminal domain of Arthrobacter globiformis glucodextranase, and a transmembrane region at the C-terminus. Recombinant DDE released glucose from α-(l→2)-branched α-glucans produced by Leuconostoc citreum strains B-1299, S-32, and S-64 and showed weak hydrolytic activity with kojibiose and kojitriose. No activity was detected for commercial dextran and Leuconostoc citreum B-1355 α-glucan, which do not contain α-(1→2)-linkages. The removal of the D-domain decreased the affinity for a-(1→2)-branched α-glucans but not for kojioligosaccharides, suggesting that D-domain plays a role in α-glucan binding. Genes for putative dextranases, oligo-1,6-glucosidase, sugar-binding protein, and permease were present in the vicinity of the DDE gene, and as a result these gene products may be necessary for the use of α-(l→2)-branched glucans. Our findings shed new light on how actinobacteria utilize polysaccharides produced by lactic acid bacteria. [ABSTRACT FROM AUTHOR]

Salt stress represents one of the most problematic abiotic stress affecting plants worldwide. In saline soils, plants try to counteract the consequences of salt stress by physiological changes, leading to the decreasing of both osmotic and oxidative stresses. Plant growth-promoting bacteria (PGPB) can ameliorate plant stress response by several mechanisms. In this work, we focused on the effects of halotolerant strain Arthrobacter globiformis on salt stress response in Brassica napus. The strain was inoculated on seeds of three rapeseed cultivars with different levels of salt tolerance; seed germination and following first phases of development were examined in plants exposed to high salinity. Compared to not inoculated plants under the same saline conditions, the inoculated showed a better stress response in the seedling phase. Moreover, a significant increase in phenolic compounds, as well as in Phenylalanine ammonia-lyase (PAL) and Superoxide dismutase (SOD) enzymatic activities were observed in inoculated plants; the concentration of the osmolyte proline was also significantly enhanced in comparison to the not inoculated ones. A. globiformis was proved to be a promising PGPB strain and it can be a tool to counteract salt stress in quite an effective manner, even at high saline conditions. [ABSTRACT FROM AUTHOR]

Bacteriophages Uzumaki and Argan infect Arthrobacter globiformis B-2880 isolated from soil samples in Long Island, New York. These bacteriophages have lambda-like morphology with prolate capsid and share 97% gene content similarity. These traits place them in cluster AU6 with other related Arthrobacter phages., Competing Interests: The authors declare no conflict of interest.

Janeemi is a bacteriophage that infects Arthrobacter globiformis B-2880, which was isolated from soil collected in New York City. The genome has a length of 43,877 bp and contains 69 predicted genes. Based on gene content similarity to phages in the actinobacteriophage database, Janeemi is assigned to phage cluster AZ1., Competing Interests: The authors declare no conflict of interest.

Choline oxidase catalyzes the oxidation of choline to glycine betaine via betaine aldehyde in glycine betaine biosynthesis and betaine acts as an osmolyte. Choline oxidase has attracted a great deal of attention because of its wide application in clinical and its potential use in enzymatic betaine production. Therefore, the development of efficient methods for overexpression of choline oxidase will be very valuable. In the present study, the choline oxidase gene was amplified from a newly isolated Gram-positive soil Arthrobacter globiformis strain HYJE003 and was cloned into a pET expression vector. Furthermore, the culture conditions were optimized for overexpression of cloned choline oxidase gene in different hosts for periplasmic expression of the enzyme. Expression host system Rosetta-gami2(DE3)pLysS yielded more cell-free protein and 20 fold higher active enzyme compared to any other reported studies. Terrific Broth media were found to be yielding the highest cell biomass, by applying the optimized culture conditions and purification strategy 20,902 U of choline oxidase was produced with a specific activity of 95 U/mg. The optimum pH and temperature for the enzyme activity were found to be 7 and 37 °C, respectively. Finally, we have demonstrated efficient bioconversion of betaine using overexpressed and purified choline oxidase enzyme. The enzymatically produced betaine was estimated by the formation of betaine reineckate and we were able to produce 0.83 molar of betaine from one molar of choline chloride. [ABSTRACT FROM AUTHOR]

Urate oxidase derived from Aspergillus flavus has been investigated as a treatment for tumor lysis syndrome, hyperuricemia, and gout. However, its long-term use is limited owing to potential immunogenicity, low thermostability, and short circulation time in vivo. Recently, urate oxidase isolated from Arthrobacter globiformis (AgUox) has been reported to be thermostable and less immunogenic than the Aspergillus-derived urate oxidase. Conjugation of human serum albumin (HSA) to therapeutic proteins has become a promising strategy to prolong circulation time in vivo. To develop a thermostable and long-circulating urate oxidase, we investigated the site-specific conjugation of HSA to AgUox based on site-specific incorporation of a clickable non-natural amino acid (frTet) and an inverse electron demand Diels–Alder reaction. We selected 14 sites for frTet incorporation using the ROSETTA design, a computational stability prediction program, among which AgUox containing frTet at position 196 (Ag12) exhibited enzymatic activity and thermostability comparable to those of wild-type AgUox. Furthermore, Ag12 exhibited a high HSA conjugation yield without compromising the enzymatic activity, generating well-defined HSA-conjugated AgUox (Ag12-HSA). In mice, the serum half-life of Ag12-HSA was approximately 29 h, which was roughly 17-fold longer than that of wild-type AgUox. Altogether, this novel formulated AgUox may hold enhanced therapeutic efficacy for several diseases.

In the catalytic reaction of copper amine oxidase, the protein-derived redox cofactor topaquinone (TPQ) is reduced by an amine substrate to an aminoresorcinol form (TPQamr), which is in equilibrium with a semiquinone radical (TPQsq). The transition from TPQamr to TPQsq is an endothermic process, accompanied by a significant conformational change of the cofactor. We employed the humid air and gluecoating (HAG) method to capture the equilibrium mixture of TPQamr and TPQsq in noncryocooled crystals of the enzyme from Arthrobacter globiformis and found that the equilibrium shifts more toward TPQsq in crystals than in solution. Thermodynamic analyses of the temperaturedependent equilibrium also revealed that the transition to TPQsq is entropy-driven both in crystals and in solution, giving the thermodynamic parameters that led to experimental determination of the crystal packing effect. Furthermore, we demonstrate that the binding of product aldehyde to the hydrophobic pocket in the active site produces various equilibrium states among two forms of the product Schiff-base, TPQamr, and TPQsq, in a pH-dependent manner. The temperature-controlled HAG method provides a technique for thermodynamic analysis of conformational changes occurring in protein crystals that are hardly scrutinized by conventional cryogenic X-ray crystallography. [ABSTRACT FROM AUTHOR]

Glucose dehydrogenase (GlcDH) is the rate-limiting catalyst for microbial conversion of glucose to the important organic acid 2-ketogluconic acid (2KGlcA). In this study, a D-glucose dehydrogenase was purified from the industrial 2KGlcA producer Arthrobacter globiformis C224. After four purification steps, the GlcDH was successfully purified over 180 folds and specific activity of 88.1 U/mg. A single protein band of 87 kDa was detected by SDS-PAGE. The purified GlcDH had the broad substrate specificity with the Km values for D-glucose, D-xylose, D-galactose and maltose of 0.21 mM, 0.34 mM, 0.46 mM and 0.59 mM, respectively. The kinetic studies proved that A. globiformis GlcDH followed the ping-pong kinetic mechanism. The GlcDH showed an optimum catalytic activity at pH 5.0 and 45 °C with the stable activity at temperature of 20–40 °C and pH of 6.0–7.0. Organic solvents, metal ions or EDTA could significantly influence the GlcDH activity to different degrees.

We report the discovery and genome sequence of bacteriophage Aoka, an actinobacteriophage isolated from a soil sample in Pueblo, Colorado using Arthrobacter globiformis , B2880-SEA. Its genome length is 36,744 base pairs with 54 protein-coding genes. Based on gene content similarity to other actinobacteriophages, Aoka is assigned to cluster FO., Competing Interests: The authors declare no conflict of interest.

The X‐ray structure of ketose 3‐epimerase from Arthrobacter globiformis M30, which was previously reported to be a d‐allulose 3‐epimerase (AgD‐AE), was determined at 1.96 Å resolution. The crystal belonged to the hexagonal space group P6522, with unit‐cell parameters a = b = 103.98, c = 256.53 Å. The structure was solved by molecular replacement using the structure of Mesorhizobium loti l‐ribulose 3‐epimerase (MlL‐RE), which has 41% sequence identity, as a search model. A hexagonal crystal contained two molecules in the asymmetric unit, and AgD‐AE formed a homotetramer with twofold symmetry. The overall structure of AgD‐AE was more similar to that of MlL‐RE than to the known structures of d‐psicose (alternative name d‐allulose) 3‐epimerases ( d‐PEs or d‐AEs), although AgD‐AE and MlL‐RE have different substrate specificities. Both AgD‐AE and MlL‐RE have long helices in the C‐terminal region that would contribute to the stability of the homotetramer. AgD‐AE showed higher enzymatic activity for l‐ribulose than d‐allulose; however, AgD‐AE is stable and is a unique useful enzyme for the production of d‐allulose from d‐fructose. [ABSTRACT FROM AUTHOR]

2-Keto-D-gluconic acid (2KGA) is mainly used for industrial production of erythorbic acid, a food antioxidant. In this study, a 2KGA producing strain JUIM02 was firstly identified as Arthrobacter globiformis by morphological observation and 16S rDNA sequencing. The 2KGA synthetic capacity of A. globiformis JUIM02 was evaluated by both fermentation and bioconversion, with 180 g/L dextrose monohydrate as substrates, in shake flasks and 5 L fermenters. For fermentation, 2KGA titer, yield, molar yield, and productivity of JUIM02 reached 159.05 g/L, 0.97 g/g, 90.18%, and 6.63 g/L/h in 24 h. For non-sterile and buffer-free bioconversion by free resting cells (~ 3.2 g/L dry cell weight) of JUIM02, these data were 172.96 g/L, 1.06 g/g, 98.07%, and 5.41 g/L/h in 32 h. Moreover, JUIM02 resting cells could be repeatedly used. Resting cells stored at 4 °C within 30 days showed stable bioconversion capacity, with 2KGA titers ≥ 171.50 g/L, yields ≥ 1.04 g/g, and molar yields ≥ 97.24%. The 2KGA synthetic pathway in A. globiformis, which was rarely reported, was also speculated similar to Pseudomonas and verified preliminarily. In conclusion, A. globiformis JUIM02 is a promising 2KGA industrial-producing strain suitable for various production methods and a suitable object for 2KGA metabolism research of A. globiformis. [ABSTRACT FROM AUTHOR]

Field-scale bioremediation of dichlorodiphenyl trichloroethanes (DDTs) and polycyclic aromatic hydrocarbons (PAHs) contaminated farmland soil from the Shenyang North New Area of China was studied using the bacteria Arthrobacter globiformis. The additive effects of different concentrations of biosurfactant rhamnolipids (RLs) and anionic–nonionic mixed surfactant (SDBS–Tween 80) were evaluated. DDT and PAH removal rates by A. globiformis after 150 days of remediation were 52.1% and 21.9%, respectively. At the optimum RL concentration of 5 mg kg−1, DDTs and PAHs had removal rates of 64.3% and 35.6%, respectively, at 150 days. This was 60.7% and 29.3% higher than the control; 36.9% and 19.8% higher than soil with RL-5 alone; and 12.2% and 13.8% higher than the A. globiformis treatment alone. RL-5 can enhance soil enzyme activity and A. globiformis reproduction during the DDT and PAH biodegradation processes. This study illustrates a highly efficient, low-cost in situ soil bioremediation technology that could have practical utility. [ABSTRACT FROM AUTHOR]

The contact assay measuring the inhibition of Arthrobacter globiformis dehydrogenase activity as an endpoint to evaluate the toxicity of solid samples was tested in an international ring-test to validate its performance for ISO standardization (ISO/CD 18187). This work reports the results of the ring-test involving 9 laboratories from six countries. At least 8 valid data sets were obtained for each sample and more than three quarters of the participants attained the validity criteria defined in the standard. The coefficient of variation within (CV r ) and between (CV R ) laboratories was generally on average <15% and <30% for negative and positive controls, respectively. Regarding solid samples, the laboratories provided a similar ranking of the samples based on their toxicity, despite some variation in the LOEC values. The logarithmic within-lab standard deviation <0.50 for soils and <0.25 for wastes evidenced a good repeatability. The between-lab variability assessed by a CV R <30%, minimum-maximum factor <4 and a reproducibility standard deviation (SD R ) <0.13 for a great part of the solid samples, confirmed the test reproducibility. Overall, this assay proved to be robust, sensitive and feasible for routine use towards the quality assessment of soils and wastes. [ABSTRACT FROM AUTHOR]

The study aims to establish a preliminary environmental assessment of a quinaldine-based LOHC system composed of hydrogen-lean, partially hydrogenated, and fully hydrogenated forms. We examined their toxicity toward the soil bacteria Arthrobacter globiformis and the Collembola Folsomia candida in two exposure scenarios, with and without soil, to address differences in the bioavailability of the compounds. In both scenarios, no or only slight toxicity toward soil bacteria was observed at the highest test concentration (EC50 > 3397 μmol L-1 and >4892 μmol kg-1 dry weight soil). The effects of the three quinaldines on F. candida in soil were similar, with EC50 values ranging from 2119 to 2559 μmol kg-1 dry weight soil based on nominal concentrations. Additionally, corrected pore-water-concentration-based EC50 values were calculated by equilibrium partitioning using soil/pore-water distribution coefficients. The tests without soil (simulating pore-water exposure) revealed higher toxicity, with LC50 values between 78.3 and 161.6 μmol L-1 and deformation of the protective cuticle. These results assign the compounds to the category “harmful to soil organisms”. Potential risks toward the soil environment of the test compounds are discussed on the basis of predicted no-effect concentrations. [ABSTRACT FROM AUTHOR]

The ability of Arthrobacter arilaitensis Y-10 for nitrogen removal from simulated wastewater was studied. Results showed that ammonium was the best inorganic nitrogen for strain Y-10’s cell growth, which could also promote nitrate reduction. Approximately 100.0% of ammonium was removed in the nitrogen removal experiments. The nitrate removal efficiency was 73.3% with nitrate as sole nitrogen source, and then the nitrate efficiency was increased to 85.3% and 100.0% with ammonium and nitrate (both about 5 or 100 mg/L) as the mixed nitrogen sources. Nitrite accumulation was observed in presence of ammonium and nitrate. When the concentration of sole nitrite nitrogen was 10.31 mg/L, the nitrite removal efficiency was 100.0%. Neither ammonium nor nitrate was accumulated during the whole experimental process. All experimental results indicated that A. arilaitensis Y-10 could remove ammonium, nitrate and nitrite at 15 °C from wastewater, and could also perform simultaneous nitrification and denitrification under aerobic condition. [ABSTRACT FROM AUTHOR]

An enzyme that catalyzes C-3 epimerization between d -fructose and d -allulose was found in Arthrobacter globiformis strain M30. Arthrobacter species have long been used in the food industry and are well-known for their high degree of safety. The enzyme was purified by ion exchange and hydrophobic interaction chromatographies and characterized as a d -allulose 3-epimerase ( d -AE). The molecular weight of the purified enzyme was estimated to be 128 kDa with four identical subunits. The enzyme showed maximal activity and thermostability in the presence of Mg 2+ . The optimal pH and temperature for enzymatic activity were 7.0–8.0 and 70°C, respectively. The enzyme was immobilized to ion exchange resin whereupon it was stable for longer periods than the free enzyme when stored at below 10°C. In the column reaction, the enzyme activity also maintained stability for more than 4 months. Under these conditions, 215 kg of d -allulose produced per liter immobilized enzyme, and this was the highest production yield of d -allulose reported so far. These highly stable properties suggest that this enzyme represents an ideal candidate for the industrial production of d -allulose. [ABSTRACT FROM AUTHOR]

The increasing contamination of soil, sediment, and water with heavy metals by natural and industrial processes is a worldwide problem. Many bacteria and microalgae have demonstrated ability to absorb toxic elements. To study mercury biosorption by bacteria Arthrobacter globiformis and microalga Spirulina platensis neutron activation analysis (NAA) was applied. The process of mercury biosorption by these media was described by Freundlich and Langmuir-Freundlich Model. Both microorganisms showed a great potential to be used as biosorbing agents for mercury removal from the environment.

Background: Ionic liquids (ILs) are a promising alternative for organic solvents because these liquids exhibit unique properties and enhanced steroid 1-dehydrogenation biotransformation caused by Arthrobacter simplex CPCC 140451 (ASP). However, the effect of ILs on the whole cell itself remains poorly understood and must be further investigated. Results: A comparative investigation was performed to determine the effect of imidazolium-based ILs, namely, hydrophobic [PrMIm]PF6, and hydrophilic [PrMIm]BF4, on the steroid conversion, activity, permeability, and material basis of ASP cells. Both ILs weakened permeability barriers, enhanced steroid transformation, whereas reduced the activity of cells. The influence of [PrMIm]PF6 on the steroid conversion, permeability and activity of cells is more serious than that of [PrMIm]BF4 Transmission electron microscopy micrographs directly showed wrinkles, gross creases, and several small pores in ILs-treated cells surface. The total lipid content of [PrMIm]BF4-treated cells reduced by 8.3 %, while that of [PrMIm]PF6-treated cells reduced twice more, among which the content of long-chain fatty acids was decreased, whereas the content of unsaturated fatty acids was increased. The protein profile of LC-MS/MS revealed that the reduced proteins of cells treated with the two ILs were mainly located in the cytoplasm and plasma membrane, 19.27 % of reduced proteins were located on the cell membrane for [PrMIm]PF6-pretreated cells, whereas only 12.8 % for [PrMIm]BF4-pretreated cells. It suggests that most reduced proteins functioned in energy production and conversion, material transport and metabolism, signal recognition and transmission, transcription, and translation and posttranslational modification. In particular, the identified differential proteins functioned in the pentose phosphate pathway, synthesis of purines and pyrimidines, and oxidative phosphorylation and fatty acid pathway. Conclusion: Treatment with ILs improved permeability at the molecular level and exerted significant positive effects on steroid conversion. This study provides a material basis and elucidates the mechanisms underlying cellular changes that enhanced conversion rate. [ABSTRACT FROM AUTHOR]

The feasibility of biochemical oxidation of a mixture of polyaromatic hydrocarbons (PAHs) in the absence of other sources of carbon and energy by the community of hydrocarbon-oxidizing bacteria (HOB) of Pseudomonas stutzeri, Pseudomonas putida, Bacillus cereus, and Arthrobacter globiformis species has been shown. The population of microorganisms has increased from 0.25 × 10 to 11 × 10 CFU/mL of medium during culturing, accompanied by an increase in their oxygenase activity. All the identified PAHs have undergone oxidation: the degree of degradation of biarenes, triarenes, tetraarenes, pentaarenes, and hexaarenes and their methylated homologues has varied from 11.3 to 100%. [ABSTRACT FROM AUTHOR]

Iron deficiency is common among graminaceous crops. Ecologically successful wild grasses from iron-limiting habitats are likely to harbour bacteria which secrete efficient high-affinity iron-chelating molecules (siderophores) to solubilize and mobilize iron. Such siderophore-producing rhizobacteria may increase the iron-stress resilience of graminaceous crops. Considering this, 51 rhizobacterial isolates of Dichanthium annulatum from iron-limiting abandoned mine (~84% biologically unavailable iron) were purified and tested for siderophore production; and efficacy of Arthrobacter globiformis inoculation to increase iron-stress resilience of maize and wheat was also evaluated. 16S rRNA sequence analyses demonstrated that siderophore-producing bacteria were taxonomically diverse (seven genera, nineteen species). Among these, Gram-positive Bacillus (eleven species) was prevalent (76.92%). A. globiformis, a commonly found rhizobacterium of graminaceous crops was investigated in detail. Its siderophore has high iron-chelation capacity (ICC: 13.0 ± 2.4 μM) and effectively dissolutes diverse iron-complexes (FeCl3: 256.13 ± 26.56 μM/ml; Fe2O3 red: 84.3 ± 4.74 μM/ml; mine spoil: 123.84 ± 4.38 μM/ml). Siderophore production (ICC) of A. globiformis BGDa404 also varied with supplementation of different iron complexes. In plant bioassay with iron-deficiency sensitive species maize, A. globiformis inoculation triggered stress-associated traits (peroxidase and proline) in roots, enhanced plant biomass, uptake of iron and phosphate, and protein and chlorophyll contents. However, in iron deficiency tolerant species wheat, growth improvement was marginal. The present study illustrates: (i) rhizosphere of D. annulatum colonizing abandoned mine as a "hotspot" of siderophore-producing bacteria; and (ii) potential of A. globiformis BGDa404 inoculation to increase iron-stress resilience in maize. A. globiformis BGDa404 has the potential to develop as bioinoculant to alleviate iron-stress in maize. [ABSTRACT FROM AUTHOR]

Purpose – Dulcitol (Galactitol) is a sugar alcohol which is produced by redox reaction of galactose. It has been reported that the D-tagatose can be produced from dulcitol (D-galactitol) via the oxidation reaction by the acetic acid bacteria such as Arthobacter globiformis, Gluconobacter oxydans. The D-tagatose sugar is a ketohexose monosaccharide sweetener, which is an isomer of D-galactose. D-tagatose is rarely found in nature and it can be utilized in many ways particular in prebiotic property. The purpose of this paper is to speak about the production and kinetics of D-tagatose from dulcitol using a wild strain of Arthobacter globiformis MTCC 944. Design/methodology/approach – The wild strain Arthobacter globiformis was procured from Microbial Type Culture Collection, Chandigarh and was grown in slants (Dulcitol of 2 percent (w/v)) by sub culturing for every two weeks until transferred to production medium containing 10 percent (w/v) of dulcitol operating aerobically at 25°C and 180 rpm. Biomass estimation was carried out taking samples periodically and measuring its OD value using spectronic-20D spectrophotometer at 600 nm. Kinetics of biomass was determined using Logistic growth kinetic model and that of D-tagatose production was estimated using Leudking-Piret model. Findings – The maximum production of D-tagatose (3.82 g/L) was obtained at the initial dulcitol concentration of 20 g/L and at a pH of 6.0 and temperature of 25°C. Effect of inoculum size on the fermentation of D-tagatose was studied. Threefold increases in yield of tagatose was achieved at the higher inoculum concentration of 24 percent v/v. Originality/value – The strain Arthrobacter globiformis, selected for the production of D-tagatose is not much investigated strain. Dulcitol, the substrate chosen for the study is less expensive when compare with galactose which is largely used by the investigators. [ABSTRACT FROM AUTHOR]

The purpose of the present study was to assess the hazard potentials of contaminated suspended particulate matter (SPM) sampled during a flood event for floodplain soils using in vitro bioassays and chemical analysis. Sediment-contact tests were performed to evaluate the direct exposure of organisms to native soils and SPM at two different trophic levels. For comparison, acetonic extracts were tested using both contact tests and additionally two cell-based biotests for cytotoxicity and Ah receptor-mediated activity (EROD-Assay). The sediment-contact tests were carried out with the dehydrogenase assay with Arthrobacter globiformis and the fish embryo assay with Danio rerio. The results of this study clearly document that native samples may well be significantly more effective than corresponding extracts in the bacteria contact assay or the fish embryo test. These results question the commonly accepted concept that acetonic extracts are likely to overestimate the toxicity of soil and SPM samples. Likewise, the priority organic compounds analyzed failed to fully explain the toxic potential of the samples. The outcomes of this study revealed the insufficient knowledge regarding the relationship between the different exposure pathways. Finally, there is concern about adverse effects by settling suspended particulate matter and remobilized sediments in frequently inundated floodplain soils due to an increase of the hazard potential, if compared with infrequently inundated floodplain soils. We showed that the settling of SPM and sediments revealed a significant impact on the dioxin-like potencies of riparian soils. [ABSTRACT FROM AUTHOR]

The catalytic reaction of copper amine oxidase proceeds through a ping-pong mechanism comprising two half-reactions. In the initial half-reaction, the substrate amine reduces the Tyrderived cofactor, topa quinone (TPQ), to an aminoresorcinol form (TPQamr) that is in equilibrium with a semiquinone radical (TPQsq) via an intramolecular electron transfer to the active-site copper.Wehave analyzed this reductive half-reaction in crystals of the copper amine oxidase from Arthrobacter globiformis. Anerobic soaking of the crystals with an amine substrate shifted the equilibrium toward TPQsq in an "on-copper" conformation, in which the 4-OH group ligated axially to the copper center, which was probably reduced to Cu(I). When the crystals were soaked with substrate in the presence of halide ions, which act as uncompetitive and noncompetitive inhibitors with respect to the amine substrate and dioxygen, respectively, the equilibrium in the crystals shifted toward the "off-copper" conformation of TPQamr. The halide ion was bound to the axial position of the copper center, thereby preventing TPQamr from adopting the on-copper conformation. Furthermore, transient kinetic analyses in the presence of viscogen (glycerol) revealed that only the rate constant in the step of TPQamr/TPQsq interconversion is markedly affected by the viscogen, which probably perturbs the conformational change. These findings unequivocally unequivocally demonstrate that TPQ undergoes large conformational changes during the reductive half-reaction. [ABSTRACT FROM AUTHOR]

The feasibility of biochemical oxidation of a mixture of waste petroleum oils has been shown using a model system with the introduction of hydrocarbon-oxidizing microorganisms represented by the Pseudomonas stutzeri, Pseudomonas putida, Bacillus cereus, and Arthrobacter globiformis species. The number of the microorganisms increases to 45 × 10 CFU/mL of medium during the oxidation. The proposed method involving the discharge of metabolic products during the experiment ensures the biodegradation efficiency on the order of 92% for 60 days starting from a waste oil concentration of 25 or 50 wt %. It is shown that all of the hydrocarbons present in the waste oil have been microbiologically oxidized by 79-100%. A mixture of waste vacuum oils has been subjected to instrumental analysis. The study has revealed that the biodegraded oil contains almost no oxygenated compounds in the free form. All the intermediate metabolites pass to the aqueous phase and either undergo complete mineralization or are included in the metabolism of the bacterial cell. [ABSTRACT FROM AUTHOR]

Arthrobacter globiformis C224 is an industrial 2-keto-gluconic acid (2KGA) producer and currently used for erythorbic acid production in China. In the present study, a membrane-bound gluconate dehydrogenase (GADH) with specific activity of 326.06 U/mg and purification fold of 412 was purified from A. globiformis using a five-step procedure including ultrasonication, phase separation with Triton X-114, ammonium sulfate fractionation, DEAE-sepharose fast flow and hydroxyapatite column chromatography. The GADH was identified as to be flavin adenine dinucleotide (FAD)-dependent and consisted of three subunits with molecular mass of 66,000 Da, 44,000 Da and 23,000 Da. The optimal pH and temperature of A. globiformis GADH were 5.0 and 40 °C, respectively. It had the stable activity at pH of 5.0–7.0 or below 50 °C, and the strict substrate specificity for d -gluconate with the K m of 3.15 mmol L −1 , 1.04 mmol L −1 at pH 5.0 and pH 6.0, respectively. The GADH activity also was significantly influenced by metal ions, organic solvents, and organic acids. Our study will benefit for better understanding of 2KGA production process by A. globiformis C224. [ABSTRACT FROM AUTHOR]

A new formulation of the bireagent kit for serum uric acid assay was developed based on the effects of pH on enzyme stability. At 4 °C, half-lives of uricases from Bacillus fastidious and Arthrobacter globiforms were longer than 15 months at pH 9.2, but became shorter at pH below 8.0; half-lives of ascorbate oxidase and peroxidase were comparable at pH 6.5 and 7.0, but became much shorter at pH higher than 7.4. In the new formulation of the bireagent kit, Reagent A contained peroxidase, 4-aminoantipyrine, and ascorbate oxidase in 50 mM phosphate buffer at pH 6.5; Reagent B contained B. fastidious or A. globiforms uricase in 50 mM sodium borate buffer at pH 9.2; Reagents A and B were mixed at 4:1 to produce a final pH from 7.2 to 7.6 for developing a stable color. The new bireagent kit consumed smaller quantities of three enzymes for the same shelf life. With the new bireagent kit, there were linear responses of absorbance at 546 nm to uric acid up to 34 mM in reaction mixtures and a good correlation of uric acid levels in clinical sera with those by a commercial kit, but stronger resistance to ascorbate. Therefore, the new formulation was advantageous. [ABSTRACT FROM AUTHOR]

Aim. To study the dynamics of auto-oscillations arising at the level of enzyme-substrate interaction in a cell and to find the conditions for the self-organization and the formation of chaos in the metabolic process. Methods. A mathematical model of the metabolic process of steroids transformation in Arthrobacter globiformis. The mathematical apparatus of nonlinear dynamics. Results. The bifurcations resulting in the appearance of strange attractors in the metabolic process are determined. The projections of the phase portraits of attractors are constructed for some chosen modes. The total spectra of Lyapunov's indices are calculated. The structural stability of the attractors obtained is studied. By the general scenario of formation of regular and strange attractors, the structural-functional connections in the metabolic process in the cell are found. Their physical nature is investigated. Conclusions. The presented model explains the mechanism of formation of auto-oscillations observed in the A. globiformis cells and demonstrates a possibility of the mathematical modeling of metabolic processes for the physical explanation of the self-organization of a cell and its vital activity. [ABSTRACT FROM AUTHOR]

Highlights: [•] The assay gave rapid and feasible discrimination of toxic soils to A. globiformis. [•] Sensitive and low variability response to soils from different regions. [•] Soil properties may interfere with metal toxicity and fluorescence measurements. [•] Proposal of a toxicity threshold for the contact assay regarding soils. [•] A. globiformis assay should be included in the Tier I of risk assessment frameworks. [ABSTRACT FROM AUTHOR]

Industrial waste substrates, sugarcane molasses, and corn steep liquor were used for production of carotenes by Arthrobacter globiformis in this study. At the first stage, a one-factor-at-a-time approach was used for optimization of different media components such as carbon, nitrogen, MgSO4 · 7H2O, and KH2PO4, as well as pH, temperature, liquid medium volume, and inoculums level. The response surface method was further applied to determination of optimum values of process variables for maximum carotenes concentration. Results showed that the optimum combination for carotenes formation was as follows (g/L): sugarcane molasses, 40.00; corn steep liquor, 50.00; MgSO4 · 7H2O, 0.75; KH2PO4, 1.00. The maximum carotene concentration of 1.19 ± 0.02 mg/g dry biomass, about 113% of 1.05 ± 0.02 mg/g dry biomass growing in basal medium, was demonstrated by confirmatory experiments to be the optimum in liquid medium at 100 rpm, 30°C, initial pH of 7.5, and cultivation for 60 hr. In a second stage, detailed studies showed about 1.64-fold and 1.43-fold increase in carotene concentration (mg/g dry biomass) in the presence of addition of ethanol (4%, v/v) and addition of hydrogen peroxide (4%, v/v) at 40 hr, and 32 hr in liquid medium, separately. [ABSTRACT FROM AUTHOR]

Silver nanoparticles (AgNPs) are widely applied for their antibacterial activity. Their increasing use in consumer products implies that they will find their way into the environment via wastewater-treatment plants. The aim of the present study was to compare the ecotoxicological impact of 2 differently designed AgNPs using the solid contact test for the bacterial strain Arthrobacter globiformis. In addition, a miniaturized version of this test system was established, which requires only small-sized samples because AgNPs are produced in small quantities during the design level. The results demonstrate that the solid contact test can be performed in 24-well microplates and that the miniaturized test system fulfills the validity criterion. Soils spiked with AgNPs showed a concentration-dependent reduction of Arthrobacter dehydrogenase activity for both AgNPs and Ag ions (Ag+). The toxic effect of the investigated AgNPs on the bacterial viability differed by 1 order of magnitude and can be related to the release of dissolved Ag+. The release of dissolved Ag+ can be attributed to particle size and surface area or to the fact that AgNPs are in either metallic or oxide form. Environ Toxicol Chem 2014;33:1142-1147. © 2014 SETAC [ABSTRACT FROM AUTHOR]

The crystal structure of a copper amine oxidase from Arthrobacter globiformis was determined at 1.08 Å resolution with the use of low-molecular-weight polyethylene glycol (LMW PEG; average molecular weight ~200) as a cryoprotectant. The final crystallographic R factor and Rfree were 13.0 and 15.0%, respectively. Several molecules of LMW PEG were found to occupy cavities in the protein interior, including the active site, which resulted in a marked reduction in the overall ? factor and consequently led to a subatomic resolution structure for a relatively large protein with a monomer molecular weight of ~70 000. About 40% of the presumed H atoms were observed as clear electron densities in the Fo -- Fc difference map. Multiple minor conformers were also identified for many residues. Anisotropic displacement fluctuations were evaluated in the active site, which contains a post-translationally derived quinone cofactor and a Cu atom. Furthermore, diatomic molecules, most likely to be molecular oxygen, are bound to the protein, one of which is located in a region that had previously been proposed as an entry route for the dioxygen substrate from the central cavity of the dimer interface to the active site. [ABSTRACT FROM AUTHOR]

The crystal structure of a copper amine oxidase from Arthrobacter globiformis was determined at 1.08 Å resolution with the use of low-molecular-weight polyethylene glycol (LMW PEG; average molecular weight ~200) as a cryoprotectant. The final crystallographic R factor and Rfree were 13.0 and 15.0%, respectively. Several molecules of LMW PEG were found to occupy cavities in the protein interior, including the active site, which resulted in a marked reduction in the overall ? factor and consequently led to a subatomic resolution structure for a relatively large protein with a monomer molecular weight of ~70 000. About 40% of the presumed H atoms were observed as clear electron densities in the Fo -- Fc difference map. Multiple minor conformers were also identified for many residues. Anisotropic displacement fluctuations were evaluated in the active site, which contains a post-translationally derived quinone cofactor and a Cu atom. Furthermore, diatomic molecules, most likely to be molecular oxygen, are bound to the protein, one of which is located in a region that had previously been proposed as an entry route for the dioxygen substrate from the central cavity of the dimer interface to the active site. [ABSTRACT FROM AUTHOR]

A continuous conversion process of rice starch hydrolysate to 2-keto-D-gluconic acid (2KGA) by Arthrobacter globiformis C224 was developed. Its feasibility for industrial application was also evaluated. Results showed that the initial cell concentration exceeding 1.25 g/L met the continuous 2KGA production at a stable dilution rate and media composition, while the dilution rate and feeding glucose concentration had a significant effect on 2KGA production performance. The optimal operating parameters were obtained as: 0.090/h of dilution rate and 171.0 g/L of feeding glucose concentration. Under these conditions, the steady state had a produced 2KGA concentration of 124.74 g/L, average volumetric productivity of 11.23 g/L/h, and yield of 0.97 g/g. In conclusion, continuous 2KGA production by the A. globiformis C224 strain would be a superior industrial process for the production of 2KGA in terms of its high 2KGA productivity and yield. [ABSTRACT FROM AUTHOR]

The mechanism of O2reduction by copper amineoxidasefrom Arthrobacter globiformus(AGAO)is analyzed in relation to the cobalt-substituted protein. The enzymeutilizes a tyrosine-derived topaquinone cofactor to oxidize primaryamines and reduce O2to H2O2. Steady-statekinetics indicate that amine-reduced CuAGAO is reoxidized by O2>103times faster than the CoAGAO analogue.Complementaryspectroscopic studies reveal that the difference in the second orderrate constant, kcat/KM(O2), arises from the more negative redoxpotential of CoIII/IIin relation to CuII/I.Indistinguishable competitive oxygen-18 kinetic isotope effects areobserved for the two enzymes and modeled computationally using a calibrateddensity functional theory method. The results are consistent witha mechanism where an end-on (η1)-metal bound superoxideis reduced to an η1-hydroperoxide in the rate-limitingstep. [ABSTRACT FROM AUTHOR]

The biodegradation of spent saline bottles, a low-density polyethylene product (LDPE) by two select-ed Arthrobacter sp. is reported in vitro conditions. Chemical and UV pretreatment play a vital role in enhancing the rate of biodegradation. Treated LDPE films exhibit a higher weight loss and density when compared to untreated films. Arthrobacter oxydans and Arthrobacter globiformis grew better in a medium containing pretreated films than in medium containing untreated films. The decrease in density and weight loss of LDPE was also more for pretreated film when compared to untreated films indicating the effect of abiotic treatment on mechanical properties of LDPE. The decrease in the ab-sorbance corresponding to carbonyl groups and double bonds that were generated during pretreat-ment suggest that some of the double bonds were cut by Arthrobacter species. Since Arthrobacter sp. is capable of degrading urea, splitting of urea group were also seen in FTIR spectrum indicating the evidence of biodegradation after microbial incubation. The results of this study indicated that bio-degradation rate could be enhanced by exposing LDPE to calcium stearate (a pro-oxidant), which acts as photo inducer of UV irradiation. The present plastic disposal trend of waste accumulation can be minimized with this promising eco-friendly technique. [ABSTRACT FROM AUTHOR]

Abstract: Over approximately the last 15years the electron paramagnetic resonance (EPR) technique of double electron electron resonance (DEER) has attracted considerable attention since it allows for the precise measurement of the dipole–dipole coupling between radicals and thus can lead to distance information between pairs of radicals separated by up to ca. 8nm. The “deadtime free” 4-pulse DEER sequence is widely used but can suffer from poor sensitivity if the electron spin-echo decays too quickly to allow collection of a sufficiently long time trace. In this paper we present a method which takes advantage of the much greater sensitivity that the 3-pulse sequence offers over the 4-pulse sequence since the measured electron spin-echo intensity (for equal sequence lengths) is greater. By combining 3- and 4-pulse DEER time traces using a method coined DEER-Stitch (DEERS) accurate dipole–dipole coupling measurements can be made which combine the sensitivity of the 3-pulse DEER sequence with the deadtime free advantage of the 4-pulse DEER sequence. To develop the DEER-Stitch method three systems were measured: a semi-rigid bis-nitroxide labeled nanowire, the bis-nitroxide labeled protein CD55 with a distance between labels of almost 8nm and a dimeric copper amine oxidase from Arthrobacter globiformis (AGAO). [Copyright &y& Elsevier]

Abstract: Copper amine oxidases (CAOs) are a family of redox active enzymes containing a 2,4,5-trihydroxyphenylalanine quinone (TPQ) cofactor generated from post translational modification of an active site tyrosine residue. The Arthrobacter globiformis amine oxidase (AGAO) has been widely used as a model to guide the design and development of selective inhibitors of CAOs. In this study, two aryl 2,3-butadienamine analogs, racemic 5-phenoxy-2,3-pentadienylamine (POPDA) and racemic 6-phenyl-2,3-hexadienylamine (PHDA), were synthesized and evaluated as mechanism-based inactivators of AGAO. Crystal structures show that both compounds form a covalent adduct with the amino group of the substrate-reduced TPQ, and that the chemical structures of the rac-PHDA and rac-POPDA modified TPQ differ by the allenic carbon that is attached to the cofactor. A chemical mechanism accounting for the formation of the respective TPQ derivative is proposed. Under steady-state conditions, no recovery of enzyme activity is detected when AGAO pre-treated with rac-PHDA or rac-POPDA is diluted with excess amount of the benzylamine substrate (100-fold Km). Comparing the IC50 values further reveals that the phenoxy substituent in POPDA offers an approximately 4-fold increase in inhibition potency, which can be attributed to a favourable binding interaction between the oxygen atom in the phenoxy group and the active site of AGAO as revealed by crystallographic studies. This hypothesis is corroborated by the observed >3-fold higher partition ratio of PHDA compared to POPDA. Taken together, the results presented in this study reveal the mechanism by which aryl 2,3-butadienamines act as mechanism-based inhibitors of AGAO, and the potency of enzyme inactivation could be fine-tuned by optimizing binding interaction between the aryl substituent and the enzyme active site. [Copyright &y& Elsevier]

Glycine betaine (GB) could be used by Arthrobacter globiformis cells as a sole carbon source. The cells took up this molecule in the low as well as in the high salinity medium. Addition of GB to the mineral medium with high salt concentration revealed that GB was also used as an osmoprotectant. Dimethylglycine oxidase (DMGO) was involved in the catabolism of GB. Two genes for DMGO were detected in a cloned 26267 bp fragment of A. globiformis DNA. The genes involved in the tetrahydrofolate-dependent assimilation of methyl groups were located nearby the two of DMGO genes. Both cloned A. globiformis DMGO were active. The activity of DMGO was detected in A. globiformis cells and it depended on the addition of GB and the salinity of the medium. Reverse transcription-PCR demonstrated that the addition of GB influenced the transcription of dmg genes. [ABSTRACT FROM AUTHOR]

The measured response of rapid biochemical oxygen demand (BOD) biosensors is often not identical to those measured using the conventional 5-day BOD assay. This paper highlights the efficacy of using both glucose-glutamic acid (GGA) and Organisation for Economic Cooperation and Development (OECD) BOD standards as a rapid screen for microorganisms most likely to reliably predict real effluent BODs when used in rapid BOD devices. Using these two synthetic BOD standards, a microorganism was identified that produced comparable BOD response profiles for two assays, the MICREDOX® assay and the conventional 5-day BOD test. A factorial experimental design systematically evaluated the impact of four factors (microbial strain, growth media composition, media strength, and microbial growth phase) on the BOD response profiles using GGA and OECD synthetic standard substrates. An outlier was identified that showed an improved correlation between the MICREDOX® BOD (BOD) and BOD assays for both the synthetic standards and for real wastewater samples. Microbial strain was the dominant factor influencing BOD values, with Arthrobacter globiformis single cultures clearly demonstrating superior rapid BOD response profiles for both synthetic and real waste samples. It was the only microorganism to approach the BOD response for the OECD substrate (171 mg O L), and also reported BOD values for real waste samples that were comparable to those produced by the BOD test, including discriminating between filtered and unfiltered samples. [ABSTRACT FROM AUTHOR]

Instrumental neutron activation analysis was used to study accumulation of Hg(II) and Cr(VI) ions in Arthrobacter globiformis 151B, a gram-positive, Cr(VI)-reducer aerobic bacterium isolated from basalt sample taken from the most polluted region in the Republic of Georgia (Kazreti). Experiments were focused on (1) accumulation of Hg(II) in bacterial cells; (2) accumulation of Cr(VI) in A. globiformis 151B in the presence of Hg(II) and (3) effects of Hg(II) and mixture of Cr(VI)-Hg(II) on the elemental composition of bacteria. It was shown that this bacterial strain possesses uptake mechanisms by which mercury toxicity can be reduced in environment and that accumulation of Cr(VI) in A. globiformis 151B is much higher in the presence of Hg(II) ions. Accumulation of Hg(II), similar to the Cr(VI) accumulation, follows well the Lengmuir-Freundlich model. NAA measurements showed increased content of Fe in bacteria under Hg and Cr action, suggesting that Fe-containing biomolecules play a decisive role in detoxifying of heavy metals by A. globiformis 151B . A concentration of 5000 μg/L of Hg(II) was found to be critical for A. globiformis 151B . At this concentration of Hg(II) the concentrations of both essential (Na, Mg, Al, Cl, K, Mn, Zn) and some non-essential elements (Rb, Sb, Sc, As) changed drastically along with a decrease of the biomass of bacteria by a factor of two. One may assume that under this high exposure to Hg(II) the structure of the bacterial cell wall was destroyed. [ABSTRACT FROM AUTHOR]

Abstract: Arthrobacter is a genus of Gram-positive bacteria widely distributed in soil. The ability to catabolize a variety of xenobiotics has shown their potential as a detoxifying agent. Recently, Arthrobacter has been also recognized as an opportunistic pathogen. Glycolipids from A. scleromae, a clinical isolate, and A. globiformis, from soil, were isolated by chloroform–methanol extraction and subsequently purified using column chromatography and high-performance liquid chromatography. Structural studies were carried out utilizing specific chemical degradation, matrix-assisted laser-desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI FT ICR-MS), and 1D and 2D nuclear magnetic resonance (NMR) spectroscopy. The major glycolipids in A. scleromae and A. globiformis were found to be a diglycosylglycerol with the structure α-Manp-(1→3)-α-Manp-(1→3)-Gro (Man A-Man B-Gro; G1), and a monoglycosylglycerol with the structure β-Galp-(1→3)-Gro (G2). Glycolipids were acylated at positions 1 of Gro and 6 of Man B in the case of G1 and at positions 1 and 2 of Gro in the case of G2. The distribution of the fatty acids was different in both species. A. scleromae glycolipids contained heptadecanoic acid while in the A. globiformis glycolipids mainly pentadecanoic acid could be detected. The substitution by hexadecanoic acid was proportionally similar in both species. The taxonomical value of major glycolipids from Arthrobacter is also presented. [Copyright &y& Elsevier]