Arthrobacter Cells Research Articles

Comparative transcriptomic and proteomic analysis of Arthrobacter sp. CGMCC 3584 responding to dissolved oxygen for cAMP production

Arthrobacter sp. CGMCC 3584 is able to produce high yields of extracellular cyclic adenosine monophosphate (cAMP), which plays a vital role in the field of treatment of disease and animal food, during aerobic fermentation. However, the molecular basis of cAMP production in Arthrobacter species is rarely explored. Here, for the first time, we report the comparative transcriptomic and proteomic study of Arthrobacter cells to elucidate the higher productivity of cAMP under high oxygen supply. We finally obtained 14.1% and 19.3% of the Arthrobacter genome genes which were up-regulated and down-regulated notably, respectively, with high oxygen supply, and identified 54 differently expressed proteins. Our results revealed that high oxygen supply had two major effects on metabolism: inhibition of glycolysis, pyruvate metabolism, nitrogen metabolism, and amino acid metabolism (histidine, branched-chain amino acids and glutamate metabolism); enhancement of the tricarboxylic acid cycle and purine metabolism. We also found that regulation of adenylate cyclase and phosphodiesterase was not significant under high oxygen supply, suggesting efficient cAMP export might be important in cAMP production. These findings may contribute to further understanding of capacities of Arthrobacter species and would be highly useful in genetic regulation for desirable production.

Effect of bioflocculation on fouling-related biofoulants in a membrane bioreactor during saline wastewater treatments

A membrane bioreactor (MBR) was operated in two modes; with and without the inoculation of marine Arthrobacter cells, to investigate the effect of bioflocculation on membrane biofouling during saline wastewater treatments. The MBR-Arthrobacter system showed a higher resistance to membrane fouling than the normal MBR system. Lower concentrations of the fouling-related components and higher removal efficiencies of COD and NH3-N were observed in the MBR-Arthrobacter system. The bioflocculation of Arthrobacter preferred to settle down the humic acid-like, fulvic acid-like and aromatic proteins components (larger biomolecules) rather than the soluble microbial by-product-like components (smaller biomolecules).

Cesium and strontium tolerant Arthrobacter sp. strain KMSZP6 isolated from a pristine uranium ore deposit.

Arthrobacter sp. KMSZP6 isolated from a pristine uranium ore deposit at Domiasiat located in North-East India exhibited noteworthy tolerance for cesium (Cs) and strontium (Sr). The strain displayed a high minimum inhibitory concentration (MIC) of 400 mM for CsCl and for SrCl2. Flow cytometric analysis employing membrane integrity indicators like propidium iodide (PI) and thiazole orange (TO) indicated a greater sensitivity of Arthrobacter cells to cesium than to strontium. On being challenged with 75 mM of Cs, the cells sequestered 9612 mg Cs g−1 dry weight of cells in 12 h. On being challenged with 75 mM of Sr, the cells sequestered 9989 mg Sr g−1 dry weight of cells in 18 h. Heat killed cells exhibited limited Cs and Sr binding as compared to live cells highlighting the importance of cell viability for optimal binding. The association of the metals with Arthrobacter sp. KMSZP6 was further substantiated by Field Emission-Scanning Electron Microscopy (FE-SEM) coupled with Energy dispersive X-ray (EDX) spectroscopy. This organism tolerated up to 1 kGy 60Co-gamma rays without loss of survival. The present report highlights the superior tolerance and binding capacity of the KMSZP6 strain for cesium and strontium over other earlier reported strains and reveals its potential for bioremediation of nuclear waste.Electronic supplementary materialThe online version of this article (doi:10.1186/s13568-016-0247-3) contains supplementary material, which is available to authorized users.

Influence of ε-caprolactam on growth and physiology of environmental bacteria

e-Caprolactam was found to have an effect on ecologically important soil bacteria. It inhibited the growth of several Bacillus sp. and Rhizobium sp. but cells of Arthrobacter sp. were able to grow in the presence of caprolactam. Sphingomonas sp. lost its inherent capacity to produce extracellular polymer (EPS) if grown in medium containing caprolactam. In the case of raw domestic sewage, the diversity of native bacteria was diminished in presence of caprolactam. Polluted sea water yielded predominantly one type of caprolactam-degrading bacteria of the genus Achromobacter. These cells efficiently utilized up to 10 g caprolactam/L as the sole source of carbon and nitrogen in synthetic medium even in the presence of 20 g NaCl/L. Compared to cells of Arthrobacter sp., cells of Achromobacter sp. accumulated high amount of 6-aminocaproic acid due to degradation of caprolactam. When using caprolactam as sole source of carbon and nitrogen, Achromobacter cells showed unique physiological ability to produce EPS upon prolonged incubation in solid medium and in broth with low phosphate (C:N:P ratio 100:20:0.05). Hydrolyzed cell-free EPS had glucose as its major component though the only substrate provided in the medium for growth was caprolactam.

Enzyme involved in degradation of isonitrile with a nitrogen‐carbon triple bond

We have studied microbial metabolism of nitrile [R‐CN] and its isomer, isonitrile [R‐NC], both of which contain a C‐N triple bond. Although isonitriles are widely distributed in nature, information on their biological metabolism is quite limited. We obtained isonitrile‐degradable microorganisms, clarified the degradation pathway and discovered two new enzymes. Isonitrile hydratase (InhA) from Pseudomonas putida catalyzes hydration of isonitrile to N‐substituted formamide [R‐NH‐CH(=O)]. N‐substituted formamide deformylase from Arthrobacter pascens converts N‐substituted formamide to amine and formate. They have been approved as new enzymes by NC‐IUBMB. The upstream metabolism of isonitriles remains unknown in A. pascens. Therefore, we here investigated it and discovered another new enzyme involved in isonitrile degradation. At first, we found that the highest activity of isonitrile hydratase was obtained by the addition of N‐benzylformamide to the Arthrobacter cells. The isonitrile hydratase designated InhB was purified from the cell‐free extracts, and found to act on isonitriles to yield the corresponding N‐substituted formamide. InhB exhibited maximum activity at pH 7.3–7.7. Western blot analysis of the purified InhB using the anti‐InhA polyclonal antibody revealed that the primary structure of InhB did not show any similarity to that of InhA.

Microbial Production of Optically Active β-Phenylalanine through Stereoselective Degradation of Racemic β-Phenylalanine

The ability to produce (R)- or (S)-beta-phenylalanine from racemic beta-phenylalanine through stereoselective degradation was screened for. Variovorax sp. JH2 and Arthrobacter sp. the faculty of Agriculture, Kyoto University (AKU) 638 were found to be potential catalysts for (R)- and (S)-beta-phenylalanine production respectively. On 192 h cultivation of Variovorax sp. in medium containing 1.0% (w/v) racemic beta-phenylalanine, 0.46% (w/v) (R)-beta-phenylalanine with an enantiomeric purity of 99% e.e. was obtained. The initial step of the (S)-isomer degradation was stereoselective transamination. On 312 h cultivation of Arthrobacter sp. in medium containing 1.0% (w/v) racemic beta-phenylalanine, 0.51% (w/v) (R)-beta-phenylalanine with an enantiomeric purity of 90% e.e. was obtained. The initial step of the (R)-isomer degradation was supposed to be oxidative deamination. Resting cell reaction with vigorous shaking, with cells of Arthrobacter sp. as the catalyst, resulted in production of 0.49% (w/v) of (S)-beta-phenylalanine with an enantiomeric purity of 99% e.e. from 1.0% (w/v) racemic beta-phenylalanine in 45 h.

Microbial production of optically active β-phenylalanine ethyl ester through stereoselective hydrolysis of racemic β-phenylalanine ethyl ester

The ability to produce (R)- or (S)-beta-phenylalanine ethyl ester (3-amino-3-phenylpropionic acid ethyl ester, BPAE) from racemic BPAE through stereoselective hydrolysis was screened for in BPAE-assimilating microorganisms. Sphingobacterium sp. 238C5 and Arthrobacter sp. 219D2 were found to be potential catalysts for (R)- and (S)-BPAE production, respectively. On a 24-h reaction, with 2.5% (w/v) racemic BPAE (130 mM) as the substrate and wet cells of Sphingobacterium sp. 238C5 as the catalyst, 1.15% (w/v) (R)-BPAE (60 mM) with enantiomeric purity of 99% e.e. was obtained, the molar yield as to racemic BPAE being 46%. On a 48-h reaction, with 2.5% (w/v) racemic BPAE (130 mM) as the substrate and wet cells of Arthrobacter sp. 219D2 as the catalyst, 0.87% (w/v) (S)-BPAE (45 mM) with enantiomeric purity of 99% e.e. was obtained, the molar yield as to racemic BPAE being 35%. The enzyme stereoselectively hydrolyzing (S)-BPAE was purified to homogeneity from the cell-free extract of Sphingobacterium sp. 238C5. The enzyme was a monomeric protein with a molecular mass of about 42,000. The enzyme catalyzed hydrolysis of beta-phenylalanine esters, while the common aliphatic and aromatic carboxylate esters were not catalyzed.

Phosphorus Compensates Aluminium-Induced Effects on Arthrobacter Cells

Phosphorus Compensates Aluminium-Induced Effects on Arthrobacter Cells

Electron spin resonance study of copper biosorption by bacteria

The biosorption of copper by bacteria was studied by using ESR spectroscopy. Among bacteria tested, Arthrobacter nicotianae has the most excellent ability to sorb copper. The biosorption of copper by Arthrobacter cells was so rapid, affected by the solution pH, and obeys the Langmuir adsorption equilibrium. The electron spin resonance (ESR) spectra of Cu(II) in bacterial cells are axial type, having a major absorption to higher field at g ⊥ and lesser absorption to lower field at g ∥ with four lines. The ESR parameters showed that Cu(II) in the cells has the tetragonally distorted octahedral structure with nitrogen and oxygen as ligand atoms, which suggests that most of copper in bacterial cells combined with amino acid residues in the cell surface proteins. The variation of spectral patterns among bacteria could explain as the change of ligand circumstances caused by the pH of the cell surface.

Mesoporous molecular sieve (MCM-41) as support material for microbial cell immobilization and transformation of 2,4,6-trinitrotoluene (TNT): a novel system for whole cell immobilization

The physical immobilization of whole microbial cells of Arthrobacter sp., Bacillus subtilis and Micrococcus luteus on the mesoporous molecular sieve of MCM-41 was studied. Cells of Arthrobacter sp. immobilized on the matrix of MCM-41 could be successfully employed in the treatment of 2,4,6-trinitrotoluene (TNT) and its subsequent transformation to amino products. Some significant advantages observed in this novel method of immobilization were the proliferation of whole cells while on the matrix of MCM-41, increase in tolerance (from 60 to 400 mg l −1) to TNT, repeated use of the immobilized cells for 20–23 cycles and total regeneration of support material.

Humic acid effects on 2-hydroxypyridine metabolism by starving Arthrobacter crystallopoietes cells

Bacterial strains amended to soil to facilitate bioremediation of sites contaminated with organic substances must be capable of surviving and functioning in the presence of a variety of soil organic and mineral components. Thus, the influence of humic acid on 2-hydroxypyridine catabolism, retention of 2-hydroxypyridine catabolic activity by whole cells, and hydrophobicity of the Arthrobacter crystallopoietes cells was examined. Humic acid, added to the starvation medium of the arthrobacter cells, which had been acclimated to catabolize 2-hydroxypyridine, resulted in increased stability of this metabolic activity compared to that of comparable cells starved in the absence of humic acid. For example, after 7 days starvation, cells incubated in the presence of 0.1% (wt/vol) humic acid oxidized 2-hydroxypyridine at a rate of 54.9μmolh–1 compared to 14.6μmolh–1 in the absence of humic acid. Although after 1 day starvation 2.5-fold more 2-hydroxypyridine-catabolizing activity was detected in the presence of humic acid than in its absence, this enzymatic activity declined to undetectable levels after 3 days starvation both with and without humic acid in the starvation medium. No effect of humic acid was noted on protein content of the cells. Hydrophobicity of the cells was not affected by humic acid during the first 4 days of starvation but after 7 days humic acid lessened the reduction in this property. Thus, changes in cell protein content and hydrophobicity did not explain the effect of humic acid on 2-hydroxypyridine catabolism of starving A. crystallopoietes cells.

Biotechnological production of unnatural L-amino acids from D,L-5-monosubstituted hydantions. II. L-?- and L-?-naphthylalanine

Resting cells ofArthrobacter sp. (DSM 3745) with the ability to form L-tryptophan from D,L-5-(3-indolylmethy)hydantoin were used for the bioconversion of D,L-5-α- and D,L-5-β-naphthylmethylhydantoin (D,L-5-α- and D,L-5-β-NMH) to the corresponding L-amino acids. Under the optimal reaction conditions of pH 9.7 and 40°C specific productivities of 0.2 (α-naphtylalanine) and 0.6 (β-naphtylalanine) mM amino acid x g cell dry mass−1 x h−1 were obtained in a 0.1 M Na2CO3/NaHCO3-buffer in a strirred bioreactor.

Levels of trehalose and glycogen in Arthrobacter globiformis under conditions of nutrient starvation and osmotic stress.

Cells of Arthrobacter globiformis grown in carbohydrate-rich media were found to contain large quantities of low-Mr carbohydrates (800 micrograms/mg protein) and only small amounts of amino acids, in addition to high amounts of glycogen (2 mg/mg protein). At increasing osmotic values of the medium, low-Mr carbohydrate levels increased to 1300 micrograms/mg protein. Low-Mr pools were extracted from the cells with hot 75% ethanol, and subjected to thin layer, gel and gas-liquid chromatography. They turned out to consist mainly of alpha,alpha-trehalose. Levels of trehalose in Arthrobacter cells have the tendency to remain constant, both during nutrient exhaustion (resulting in glycogen consumption), and on addition of excess of carbon source to the medium (resulting in an increased glycogen content of the cells). The stress-tolerant properties of Arthrobacter (resistance to nutrient starvation, desiccation and high salt concentration) are discussed with respect to the high glycogen and trehalose contents of the cells.

Degradation of pentachlorophenol by non-immobilized, immobilized and co-immobilized Arthrobacter cells

Non-immobilized, immobilized and co-immobilized Arthrobacter (ATCC 33790) cells were examined for their ability to degrade PCP in a mineral medium. Non-immobilized cells could completely remove PCP from the aqueous phase and mineralize 77% of the added PCP within 135 h. Alginate-encapsulated cells mineralized 86% of the PCP with a similar profile as free cells. Use of co-immobilized cells (which co-immobilized cells and activated carbon in hydrogel capsules) resulted in rapid removal of PCP from the aqueous phase and extensive PCP mineralization.

Microbial transesterification of sugar‐corynomycolates

AbstractGrowing cells ofArthrobacter sp. DSM 2567 and of the bacterium M9b were able to synthesize cell‐bound glycolipids. The carbon source determined the type of sugar moiety, whereas the α‐branched‐β‐hydroxy‐fatty acid remained constant. The incubation of resting cells of both bacteria in a simple buffer medium with various carbohydrates, including oligosaccharides and derivatives, led to the corresponding carbohydrate‐corynomycolates. Predominantly an enzymatic transesterification step seems to be responsible for the formation of new glycolipids; this was established by analytical data and 14C‐labeling studies. Concerning the substrate specifity, the transesterification reaction is characterized by a regioselective manner: (i) only the primary hydroxy‐groups at C‐6 (mono‐ and disaccharide) or C‐6′ (disaccharide) were acylated; (ii) 1‐β‐ or 4‐β‐substituents (including hydroxy groups) prevented the esterification; (iii) as for disaccharides with only one nonreducing moiety, the C‐6‐ and C‐6′‐positions were esterified one after another. In the presence of two nonreducing molecular ends with two possible C‐6‐esterification positions, both positions were substituted simultaneously.With regard to the studies on localization of the esterase after cell disruption, we found the enzymatic activity bound to the cell debris. In transesterification reactions comparable to resting whole cell experiments, the cell particles also were able to produce disaccharidecorynomycolates.

Formation and Identification of Interfacial-Active Glycolipids from Resting Microbial Cells

Resting cells of Arthrobacter sp. strain DSM2567 incubated in the presence of various mono-, di-, or trisaccharides biosynthesized different glycolipids. All eight glycolipids, containing the corresponding carbohydrate moiety and one, two, or three alpha-branched beta-hydroxy fatty acids, were produced when mannose, glucose, cellobiose, maltose, and maltotriose were used as carbon sources in a simple phosphate buffer. The structures of the compounds were elucidated by means of H and C nuclear magnetic resonance spectroscopy and by chemical ionization mass spectroscopy. In high-salinity solution, the substances showed different surfactant properties. Cellobiose and maltose monocorynomycolates reduced the interfacial tension from 42 to 1 mN/m at critical micelle concentrations below 20 mg/liter.

Xanthine oxidase activity of arthrobacter x-4 cells immobilized in glutaraldehyde-crosslinked gelatin

Cells of Arthrobacter X-4 were immobilized by entrapment in gelatin crosslinked with glutaraldehyde. The xanthine oxidase activity and stability were determined at various temperatures. In comparison with bovine milk xanthine oxidase the bacterial enzyme is more stable and has a different substrate specificity. 1-Methylxanthine was oxidized on a preparative scale.

Mass-transfer effects on the rate of isomerization of D-glucose into D-fructose, catalyzed by whole-cell immobilized glucose isomerase.

The investigated catalyst system consists of immobilized Arthrobacter cells containing the enzyme glucose isomerase, which catalyzes the isomerization of glucose into fructose. The internal structure of the catalyst was determined from electrom microscope photographs of replicas of freeze-etched catalyst. On the basis of the photographs a model for the internal structure of the catalyst was proposed. This structure was subsequently used to describe the reaction including mass-transfer effects. It appeared that under normal operating conditions the external mass-transfer rate does not influence the overall rate of reaction. The effect of internal mass-transfer resistances on the overall reaction rate can well be accounted for by the so-called porous sphere model. The intrinsic kinetics of the isomerization catalyzed by the present catalyst system can be represented by a modified Michaelis-Menten equation for a reversible one-substrate reaction.

Effect of starvation on survival of three bacterial isolates from an arctic soil.

Three isolates, a Pseudomonas sp., a Bacillus sp. and an Arthrobacter sp., which had been isolated from a meadow soil at Devon Island, Canada, were subjected to starvation under varying conditions. The viabilities of the three isolates during starvation for 30 days in a carbon-free medium was assessed after the organisms had been grown continuously at varying rates in carbon- and nitrogen-limited media at 5 and 15 degrees C. Pseudomonas M216 was the most resistant to starvation stress, Bacillus M153 the least, and Arthrobacter M51 was intermediate in its response. Cells grown and starved at 5 degrees C survived longer than those at 15 degrees C. Carbon-limited Bacillus and Arthrobacter cells grown at high rates prior to starvation survived longer than those grown slowly, while in nitrogen-limited Arthrobacter the reverse was observed. The pattern of endogenous metabolism of the three isolates during starvation at 15 degrees C for 10 days was similar to that observed in other organisms. Levels of endogenous substrates such as carbohydrate and protein showed a rapid decrease in the initial 20 h of starvation, followed by a gradual decline over the remainder of the starvation period. The rates of endogenous metabolism of the isolates were positively correlated with their survival rates during starvation.

Oxidation of linear terpenes and squalene variants by Arthrobacter sp.

Cells of Arthrobacter sp. that had been isolated from soil were used to study oxidation of some linear terpenes and squalene variants. The cells oxidized geraniol, nerol, and farnesol to the corresponding aldehydes, with partial conversion of the geometrical isomerism of the alpha,beta-double bond. The squalene variant, squalene-2,3-oxide, was cleaved to 9,10-epoxygeranylacetone and geranylacetone. Squalene-2,3-22,23-dioxide was cleaved to 9,10-epoxygeranylacetone. These products were optically active, and their stereochemistry and optical purity were determined.