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PubMed2006

Contribution of ethylamine degrading bacteria to atrazine degradation in soils.

Bacterial communities that cooperatively degrade atrazine commonly consist of diverse species in which the genes for atrazine dechlorination and dealkylation are variously distributed among different species. Normally, the first step in degradation of atrazine involves dechlorination mediated by atzA, followed by stepwise dealkylation to yield either N-ethylammelide or N-isopropylammelide. As the liberated alkylamine moieties are constituents of many organic molecules other than atrazine, it is possible that a large number of alkylamine-degrading bacteria other than those previously described might contribute to this key step in atrazine degradation. To examine this hypothesis, we isolated 82 bacterial strains from soil by plating soil water extracts on agar media with ethylamine as a sole carbon source. Among the relatively large number of isolates, only 3 were able to degrade N-ethylammelide, and in each case were shown to carry the atzB gene and atzC genes. The isolates, identified as Rhizobium leguminosarum, Flavobacterium sp., and Arthrobacter sp., were all readily substituted into an atrazine-degrading consortium to carry out N-ethylammelide degradation. The distribution of these genes among many different species in the soil microbial population suggests that these genes are highly mobile and over time may lead to generation of various atrazine-degrading consortia.

Amidohydrolases↗

PubMed2006

Growth kinetics of microorganisms isolated from Alaskan soil and permafrost in solid media frozen down to -35 degrees C.

We developed a procedure to culture microorganisms below freezing point on solid media (cellulose powder or plastic film) with ethanol as the sole carbon source without using artificial antifreezes. Enrichment from soil and permafrost obtained on such frozen solid media contained mainly fungi, and further purification resulted in isolation of basidiomycetous yeasts of the genera Mrakia and Leucosporidium as well as ascomycetous fungi of the genus Geomyces. Contrary to solid frozen media, the enrichment of liquid nutrient solutions at 0 degrees C or supercooled solutions stabilized by glycerol at -1 to -5 degrees C led to the isolation of bacteria representing the genera Polaromonas, Pseudomonas and Arthrobacter. The growth of fungi on ethanol-microcrystalline cellulose media at -8 degrees C was exponential with generation times of 4.6-34 days, while bacteria displayed a linear or progressively declining curvilinear dynamic. At -17 to -0 degrees C the growth of isolates and entire soil community on 14C-ethanol was continuous and characterized by yields of 0.27-0.52 g cell C (g of C-substrate)(-1), similar to growth above the freezing point. The 'state of maintenance,' implying measurable catabolic activity of non-growing cells, was not confirmed. Below -18 to -35 degrees C, the isolated organisms were able to grow only transiently for 3 weeks after cooling with measurable respiratory and biosynthetic (14CO2 uptake) activity. Then metabolic activity declined to zero, and microorganisms entered a state of reversible dormancy.

Alaska↗

PubMed1995

Cellular location influences copper-dependent topaquinone formation for phenylethylamine oxidase expressed in Escherichia coli K-12.

Arthrobacter globiformis amine oxidase produced by Escherichia coli cells grown in copper-depleted media was reported to undergo activation due to formation of its topaquinone cofactor in a copper-dependent autocatalytic reaction. Likewise, a mutated E. coli amine oxidase located in the cytoplasm was reported to form topaquinone autocatalytically in an EDTA-sensitive reaction. Here we show unequivocally that formation of an amine oxidase lacking topaquinone is primarily a consequence of the location of the enzyme in the cytoplasm rather than the level of copper in the growth medium. For E. coli, insertion of copper into apoamine oxidase and subsequent topaquinone formation occur after export of the apoenzyme into the periplasm.

Amine Oxidase (Copper-Containing)↗

PubMed1996

Cloning and sequencing of a dextranase-encoding cDNA from Penicillium minioluteum.

A cDNA from Penicillium minioluteum HI-4 encoding a dextranase (1,6-alpha-glucan hydrolase, EC 3.2.1.11) was isolated and characterized. cDNA clones corresponding to genes expressed in dextran-induced cultures were identified by differential hybridization. Southern hybridization and restriction mapping analysis of selected clones revealed four different groups of cDNAs. The dextranase cDNA was identified after expressing a cDNA fragment from each of the isolated groups of cDNA clones in the Escherichia coli T7 system. The expression of a 2 kb cDNA fragment in E. coli led to the production of a 67 kDa protein which was recognized by an anti-dextranase polyclonal antibody. The cDNA contains 2109 bp plus a poly(A) tail, coding for a protein of 608 amino acids, including 20 N-terminal amino acid residues which might correspond to a signal peptide. There was 29% sequence identity between the P. minioluteum dextranase and the dextranase from Arthrobacter sp. CB-8.

Amino Acid Sequence↗

PubMed1999

A practicable and accurate method to differentiate between intra- and extracellular water of microbial cells.

A thermographimetric method which allows for a quick and accurate estimation of intra- and extracellular water of microbial cells is reviewed and improved. Knowledge of these fractions is important for physiological as well as for toxicological investigations. Results of the study indicate that besides the species, nutrient availability and growth conditions affect the intracellular water content. Intra- and extracellular water, dry matter, volume and density of a single cell of Arthrobacter sp. are calculated. There are indications that intracellular compartments of eukaryotes could also be investigated with this method.

Arthrobacter↗

PubMed2001

Effects of lipids on n-alkane attenuation in media supporting oil-utilizing microorganisms from the oily Arabian Gulf coasts.

The Arabian Gulf is one of the most extensively oil-polluted areas of the world. The major objectives of this work were to study whether hydrocarbon-utilizing microorganisms indigenous to that area would readily accumulate added lipids, and whether this might affect their hydrocarbon consumption potential. Two prokaryotes, Arthrobacter nicotianae KCC B35 and the unidentified organisms KCC B6, as well as one eukaryote, Candida parapsilosis KCC Y1, were selected for this study. Biomass samples of the test organisms were incubated in an inorganic medium containing various concentrations of cholesterol, stearic acid, triolein or egg-phospholipids. The results revealed that all lipid classes were readily accumulated by the three test organisms. In addition, biomass samples were incubated for 6 h in an inorganic medium containing mixtures of individual lipid classes and either n-octadecane or n-docosane. The cells were removed and the residual alkanes in the medium were quantitatively recovered and analyzed by GLC. The results showed that out of the tested lipid classes only stearic acid exhibited a common stimulatory effect on the consumption of both n-alkanes by all test organisms. Other lipid classes were either inhibitory or had less pronounced effects than stearic acid.

Alkanes↗

PubMed2006

Final steps in the catabolism of nicotine.

New enzymes of nicotine catabolism instrumental in the detoxification of the tobacco alkaloid by Arthrobacter nicotinovorans pAO1 have been identified and characterized. Nicotine breakdown leads to the formation of nicotine blue from the hydroxylated pyridine ring and of gamma-N-methylaminobutyrate (CH(3)-4-aminobutyrate) from the pyrrolidine ring of the molecule. Surprisingly, two alternative pathways for the final steps in the catabolism of CH(3)-4-aminobutyrate could be identified. CH(3)-4-aminobutyrate may be demethylated to gamma-N-aminobutyrate by the recently identified gamma-N-methylaminobutyrate oxidase. In an alternative pathway, an amine oxidase with noncovalently bound FAD and of novel substrate specificity removed methylamine from CH(3)-4-aminobutyrate with the formation of succinic semialdehyde. Succinic semialdehyde was converted to succinate by a NADP(+)-dependent succinic semialdehyde dehydrogenase. Succinate may enter the citric acid cycle completing the catabolism of the pyrrolidine moiety of nicotine. Expression of the genes of these enzymes was dependent on the presence of nicotine in the growth medium. Thus, two enzymes of the nicotine regulon, gamma-N-methylaminobutyrate oxidase and amine oxidase share the same substrate. The K(m) of 2.5 mM and k(cat) of 1230 s(-1) for amine oxidase vs. K(m) of 140 microM and k(cat) of 800 s(-1) for gamma-N-methylaminobutyrate oxidase, determined in vitro with the purified recombinant enzymes, may suggest that demethylation predominates over deamination of CH(3)-4-aminobutyrate. However, bacteria grown on [(14)C]nicotine secreted [(14)C]methylamine into the medium, indicating that the pathway to succinate is active in vivo.

Aminobutyrates↗

PubMed2006

Functional analysis of the twin-arginine translocation pathway in Corynebacterium glutamicum ATCC 13869.

Compared to those of other gram-positive bacteria, the genetic structure of the Corynebacterium glutamicum Tat system is unique in that it contains the tatE gene in addition to tatA, tatB, and tatC. The tatE homologue has been detected only in the genomes of gram-negative enterobacteria. To assess the function of the C. glutamicum Tat pathway, we cloned the tatA, tatB, tatC, and tatE genes from C. glutamicum ATCC 13869 and constructed mutants carrying deletions of each tat gene or of both the tatA and tatE genes. Using green fluorescent protein (GFP) fused with the twin-arginine signal peptide of the Escherichia coli TorA protein, we demonstrated that the minimal functional Tat system required TatA and TatC. TatA and TatE provide overlapping function. Unlike the TatB proteins from gram-negative bacteria, C. glutamicum TatB was dispensable for Tat function, although it was required for maximal efficiency of secretion. The signal peptide sequence of the isomaltodextranase (IMD) of Arthrobacter globiformis contains a twin-arginine motif. We showed that both IMD and GFP fused with the signal peptide of IMD were secreted via the C. glutamicum Tat pathway. These observations indicate that IMD is a bona fide Tat substrate and imply great potential of the C. glutamicum Tat system for industrial production of heterologous folded proteins.

Amino Acid Sequence↗

PubMed1977

New microbial growth factor.

A screening procedure was used to isolate from soil a Penicillium sp., two bacterial isolates, and a Streptomyces sp. that produced a new microbial growth factor. This factor was an absolute growth requirement for three soil bacteria. The Penicillium sp. and one of the bacteria requiring the factor, an Arthrobacter sp., were selected for more extensive study concerning the production and characteristics of the growth factor. It did not seem to be related to the siderochromes. It was not present in soil extract, rumen fluid, or any other medium component tested. It appears to be a glycoprotein of high molecular weight, and it has high specific activity. When added to the diets for a meadow vole mammalian test system, it caused an increased consumption of diet without a concurrent increase in rate of weight gain.

Animals↗

PubMed1982

Involvement of plasmids in total degradation of chlorinated biphenyls.

Acinetobacter sp. strain P6 has previously been reported to utilize biphenyl (BP) and chlorinated BPs, with accumulation of corresponding chlorobenzoic acids. Arthrobacter sp. strain M5 was isolated as a contaminant in the culture of Acinetobacter sp. strain P6 growing on 4-chlorobiphenyl and showed properties similar to P6 in the degradation of chlorinated BPs. Both strains harbored an identical plasmid of 53.7 megadaltons. These strains spontaneously lost the ability to utilize BP and 4-chlorobiphenyl with high frequency (4 to 8%) after overnight growth in nutrient broth. The BP- derivatives could not regain the BP-assimilating ability (reversion frequency, less than 10(-9) per cell per generation) but retained the plasmid with small, detectable deletions. BP+ P6 cells grown on BP or benzoate oxidized BP and 2,3-dihydroxybiphenyl and produced meta cleavage compounds from the latter compound (lambda max, 434 nm) and also from catechol (lambda max, 375 nm) through the meta pathway. On the other hand, benzoate-grown BP- segregants totally lost the BP-metabolizing activities and oxidized catechol through the ortho pathway. A combined culture of the chlorinated BP-dissimilating P6 or M5 strain (harboring the putative 53.7-megadalton plasmid specifying conversion of chlorobiphenyls to chlorobenzoic acids) and genetically constructed mono- or dichlorobenzoate-utilizing pseudomonads (harboring plasmids encoding complete utilization of mono- or dichlorobenzoates) allowed greater than 98% utilization of mono- and dichlorobiphenyls, with the liberation of equivalent amounts of chloride ions.

Acinetobacter↗

PubMed1987

Microbial desulfonation of substituted naphthalenesulfonic acids and benzenesulfonic acids.

Sulfur-limited batch enrichment cultures containing one of nine multisubstituted naphthalenesulfonates and an inoculum from sewage yielded several taxa of bacteria which could quantitatively utilize 19 sulfonated aromatic compounds as the sole sulfur source for growth. Growth yields were about 4 kg of protein per mol of sulfur. Specific degradation rates were about 4 to 14 mu kat/kg of protein. A Pseudomonas sp., an Arthrobacter sp., and an unidentified bacterium were examined. Each desulfonated at least 16 aromatic compounds, none of which served as a carbon source. Pseudomonas sp. strain S-313 converted 1-naphthalenesulfonic acid, 2-naphthalenesulfonic acid, 5-amino-1-naphthalenesulfonic acid, benzenesulfonic acid, and 3-aminobenzenesulfonic acid to 1-naphthol, 2-naphthol, 5-amino-1-naphthol, phenol, and 3-aminophenol, respectively. Experiments with 18O2 showed that the hydroxyl group was derived from molecular oxygen.

Arthrobacter↗

PubMed1990

Chlorinated biphenyl mineralization by individual populations and consortia of freshwater bacteria.

Comparative studies were performed to investigate the contribution of microbial consortia, individual microbial populations, and specific plasmids to chlorinated biphenyl biodegradation among microbial communities from a polychlorinated biphenyl-contaminated freshwater environment. A bacterial consortium, designated LPS10, was shown to mineralize 4-chlorobiphenyl (4CB) and dehalogenate 4,4'-dichlorobiphenyl. The LPS10 consortium involved three isolates: Pseudomonas testosteroni (LPS10A), which mediated the breakdown of 4CB and 4,4'-dichlorobiphenyl to 4-chlorobenzoic acid; an isolate tentatively identified as an Arthrobacter sp. (LPS10B), which mediated 4-chlorobenzoic acid degradation; and Pseudomonas putida bv. A (LPS10C), whose role in the consortium has not been determined. None of these isolates contained detectable plasmids or sequences homologous to the 4CB-degradative plasmid pSS50. A freshwater isolate, designated LBS1C1, was found to harbor a 41-megadalton plasmid that was related to the 35-megadalton plasmid pSS50, and this isolate was shown to mineralize 4CB. In chemostat enrichments with biphenyl and 4CB as primary carbon sources, the LPS10 consortium was found to outcomplete bacterial populations harboring plasmids homologous to pSS50. These results demonstrate that an understanding of the biodegradative capacity of individual bacterial populations as well as interacting populations of bacteria must be considered in order to gain a better understanding of polychlorinated biphenyl biodegradation in the environment.

Arthrobacter↗

PubMed1991

Substrate interactions of benzene, toluene, and para-xylene during microbial degradation by pure cultures and mixed culture aquifer slurries.

Benzene, toluene, and p-xylene (BTX) were degraded by indigenous mixed cultures in sandy aquifer material and by two pure cultures isolated from the same site. Although BTX compounds have a similar chemical structure, the fate of individual BTX compounds differed when the compounds were fed to each pure culture and mixed culture aquifer slurries. The identification of substrate interactions aided the understanding of this behavior. Beneficial substrate interactions included enhanced degradation of benzene and p-xylene by the presence of toluene in Pseudomonas sp. strain CFS-215 incubations, as well as benzene-dependent degradation of toluene and p-xylene by Arthrobacter sp. strain HCB. Detrimental substrate interactions included retardation in benzene and toluene degradation by the presence of p-xylene in both aquifer slurries and Pseudomonas incubations. The catabolic diversity of microbes in the environment precludes generalizations about the capacity of individual BTX compounds to enhance or inhibit the degradation of other BTX compounds.

Arthrobacter↗

PubMed1992

Isolation and characterization of a fluorene-degrading bacterium: identification of ring oxidation and ring fission products.

An Arthrobacter sp. strain, F101, able to use fluorene as the sole source of carbon and energy, was isolated from sludge from an oil refinery wastewater treatment plant. During growth in the presence of fluorene, four major metabolites were detected and isolated by thin-layer chromatography and high-performance liquid chromatography. 9-Fluorenol, 9H-fluoren-9-one, and 3,4-dihydrocoumarin were identified by UV spectra, mass spectrometry, and 300-MHz proton nuclear magnetic resonance. The fourth metabolite has been characterized, but precise identification was not possible. Since strain F101 is not able to grow with fluorenone, two different pathways of fluorene biodegradation are suggested: one supports cell growth and produces 3,4-dihydrocoumarin as an intermediate and probably the unidentified metabolite, and the other produces 9-fluorenol and 9H-fluoren-9-one and appears to be a dead-end route.

Arthrobacter↗

PubMed1993

Degradation and induction specificity in actinomycetes that degrade p-nitrophenol.

We have isolated two soil bacteria (identified as Arthrobacter aurescens TW17 and Nocardia sp. strain TW2) capable of degrading p-nitrophenol (PNP) and numerous other phenolic compounds. A. aurescens TW17 contains a large plasmid which correlated with the PNP degradation phenotype. Degradation of PNP by A. aurescens TW17 was induced by preexposure to PNP, 4-nitrocatechol, 3-methyl-4-nitrophenol, or m-nitrophenol, whereas PNP degradation by Nocardia sp. strain TW2 was induced by PNP, 4-nitrocatechol, phenol, p-cresol, or m-nitrophenol. A. aurescens TW17 initially degraded PNP to hydroquinone and nitrite. Nocardia sp. strain TW2 initially converted PNP to hydroquinone or 4-nitrocatechol, depending upon the inducing compound.

Arthrobacter↗

PubMed1993

Microbial production of D-malate from maleate.

To produce D-malate from maleate by a microbial reaction, we screened a number of maleate-utilizing microorganisms for enzyme activity by an intact cell system. The strain which showed the best productivity among the 440 strains tested was identified taxonomically as Arthrobacter sp. strain MCI2612. The optical purity of the malate produced by this strain was 100% D type. The culture and reaction conditions for the production were studied for this strain. Addition of amino acids such as L-proline, L-histidine, and L-arginine to the culture medium promoted the formation of reaction activity as well as cell growth. Under optimum conditions, 87 g of D-malate per liter was produced in 20 h. The yield was 72 mol%.

Arthrobacter↗

PubMed1994

Characterization of psychrotrophic microorganisms producing beta-galactosidase activities.

Investigations of psychrotrophic microorganisms have been limited even though the dominant environment of the Earth is cold and enzymes with high activities at low temperatures could have commercial uses. We have isolated and characterized three psychrotrophic strains with beta-galactosidase activities. The isolates, B7, D2, and D5, were gram-positive, catalase-positive, obligate aerobes. Cells observed with a scanning electron microscope appeared as rods during the early stages of growth but became coccoid during the stationary phase. An analysis of the amino acid composition of the cell walls demonstrated the presence of lysine as the predominant diamino acid in all three isolates. The cell cycle morphology and cell wall composition suggest that the three isolates are members of the genus Arthrobacter. The beta-galactosidase activities in whole cells were labile when incubated at 40 degrees C and had temperature optima about 20 degrees C below that of the enzyme encoded by the lacZ gene of Escherichia coli. Electrophoresis of extracts from the isolates in nondenaturing polyacrylamide gels detected at least two protein bands that hydrolyzed 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside (X-Gal), suggesting the presence of beta-galactosidase isozymes.

Acclimatization↗

PubMed1994

Roles of bacterial attachment and spontaneous partitioning in the biodegradation of naphthalene initially present in nonaqueous-phase liquids.

The mineralization by an Arthrobacter sp. of naphthalene initially dissolved in di(2-ethylhexyl)phthalate exhibited a slow phase followed by a rapid phase. Triton X-100, which inhibited cell attachment, prevented the onset of the second phase. Triton X-100 increased the extent of mineralization of naphthalene initially present in 2,2,4,4,6,8,8-heptamethylnonane. Cells attached to the interface mineralized the aromatic hydrocarbon at a rate four times higher than the rate of partitioning in the absence of microorganisms, but this microbial activity was markedly reduced by Triton X-100. We suggest that utilization of naphthalene originally present in nonaqueous-phase liquids may involve a partitioning-limited initial stage carried out by bacteria freely suspended in the aqueous phase and a subsequent, more rapid stage effected by bacteria present directly at the nonaqueous-liquid-water interface.

Arthrobacter↗