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PubMed1989

Rat pituitary tumor cells in serum-free culture. I. Selection of thyroid hormone-responsive and autonomous cells.

The growth of GH4C1, GH3, GH1, and GH3C15 rat pituitary tumor cell lines was studied in a serum-free medium (designated TRM-1) formulated with 1:1 (vol/vol) mixture of Ham's F12 nutrient mixture and Dulbecco's modified Eagle's medium (F12-DME) containing 15 mM 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), 50 micrograms/ml gentamicin supplemented with 10 micrograms/ml bovine insulin, 10 micrograms/ml human transferrin (Tf), 10 ng/ml selenous acid, 10 nM 3,5,3'-triiodothyronine (T3), 50 microM ethanolamine (Etn), and 500 micrograms/ml bovine serum albumin. Of the lines evaluated, only the GH1 failed to grow in TRM-1. Passage of the GH4C1 and GH3 lines from serum-containing medium into TRM-1 caused an initial selection resulting in cells that grew progressively at higher rates and finally were maintained indefinitely in TRM-1. These populations showed a requirement for supraphysiologic concentrations of T3 (1.0 to 10 nM). After adaptation of the GH4C1 line in TRM-1 for greater than or equal to 20 generations, removal of components gave a less complex mixture containing 15 mM HEPES, 50 micrograms/ml gentamicin, 10 micrograms/ml Tf, 10 nM T3, and 50 microM Etn (designated TRM-2) that supported serial passage of the cells. Under these conditions, thyroid hormone dependence was lost progressively. When T3 was removed from TRM-2 adapted cells, a third population was selected that no longer required thyroid hormones and was only slightly stimulated by T3. These studies demonstrated that the combination of serum-containing and serum-free conditions can be used to select pituitary cell populations that a) required both serum-factor(s) and T3 for optimum growth, b) required supraphysiologic concentrations of T3 without serum proteins other than Tf and albumin, and c) were completely autonomous in that they proliferated in medium supplemented only with Tf and nutrients without necessity of other serum factor(s) or T3.

Animals↗
PubMed1994

Self-assembled microstructures from 1,2-ethanediol suspensions of pure and binary mixtures of neutral and acidic biological galactosylceramides.

Optical and electron microscopy were employed to characterize microstructures formed by thermal mechanical treatment of glycol suspensions of various pure and binary mixtures of the brain-derived galactosphingolipids hydroxy fatty acid cerebroside (HFA-Cer), non-hydroxy fatty acid cerebroside (NFA-Cer) and sulfatide (S-Cer). Negative staining indicated some new features of the neutral cerebroside suspensions in glycol. HFA-Cer formed a small fraction of both unilamellar cylinders (ULCs) (lumina ca. 27 nm) and giant multilamellar cochleates in addition to the typical nonhelical multilamellar cylinders (MLCs) (lumina ca. 10-30 nm). NFA-Cer formed a gel composed of a significant fraction of very long ULCs (lumina ca. 17 nm) without helical substructure, in addition to multilamellar helical structures such as ribbons and cylinders (lumina ca. 70 nm). Anisotropic lamellar micelle-shards of NFA-Cer were also detected by negative staining. S-Cer formed short ULCs (lumina ca. 44 nm) with no obvious helical substructure. Complex mixture data are thought to result from thermodynamic and kinetic factors. HFA-Cer is highly insoluble and promotes a network of rigid intralamellar hydrogen bonding that tends to exclude other lipids. NFA-Cer stabilizes helical defects in the lamellae, and S-Cer enhances disorder or micellization. The processes of microstructure nucleation and lipid phase separation were affected by mixtures such that metastable microstructures were trapped or the length of lamellar cylinders was altered.

Animals↗
PubMed2000

Relative contributions of affinity and intrinsic efficacy to aryl hydrocarbon receptor ligand potency.

Models of receptor action are valuable for describing properties of ligand-receptor interactions and thereby contribute to mechanism-based risk assessment of receptor-mediated toxic effects. In order to build such a model for the aryl hydrocarbon receptor (AHR), binding affinities and CYP1A induction potencies were measured in PLHC-1 cells and were used to determine intrinsic efficacies for 10 halogenated aromatic hydrocarbons (HAH): 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD), 2,3,7, 8-tetrachlorodibenzofuran (TCDF), and eight polychlorinated biphenyls (PCB). TCDD, TCDF, and non-ortho-substituted PCBs 77, 81, 126, and 169 behaved as full agonists and displayed high-intrinsic efficacy. In contrast, the mono- and di-ortho-substituted PCBs bound to the AHR but displayed lower or no intrinsic efficacy. PCB 156 was a full agonist, but with an intrinsic efficacy 10- to 50-fold lower than non-ortho-substituted PCBs. PCB 118 was a very weak partial agonist. PCBs 105 and 128 were shown to be competitive antagonists in this system. The model was then used to predict CYP1A induction by binary mixtures. These predictions were tested with binary mixtures of PCB 126, 128, or 156 with TCDD. Both PCB 156 (a low-intrinsic efficacy agonist) and PCB 128 (a competitive antagonist) inhibited the response to TCDD, while the response to TCDD and PCB126 was additive. These data support the following conclusions: 1) only 1-2% of the receptors in the cell need be occupied to achieve 50% of maximal CYP1A induction by one of the high-intrinsic efficacy agonists, demonstrating the existence of "spare" receptors in this system; 2) the insensitivity of fish to ortho-substituted PCBs is due to both reduced affinity and reduced intrinsic efficacy compared to non-ortho-substituted PCBs; 3) PCB congeners exhibit distinct structure-affinity and structure-efficacy relationships. Separation of AHR ligand action into the properties of affinity and intrinsic efficacy allows for improved prediction of the behavior of complex mixtures of ligands, as well as mechanistic comparisons across species and toxic endpoints.

Animals↗
PubMed2006

Influence of dangling ends and surface-proximal tails of targets on probe-target duplex formation in 16S rRNA gene-based diagnostic arrays.

Dangling ends and surface-proximal tails of gene targets influence probe-target duplex formation and affect the signal intensity of probes on diagnostic microarrays. This phenomenon was evaluated using an oligonucleotide microarray containing 18-mer probes corresponding to the 16S rRNA genes of 10 waterborne pathogens and a number of synthetic and PCR-amplified gene targets. Signal intensities for Klenow/random primer-labeled 16S rRNA gene targets were dissimilar from those for 45-mer synthetic targets for nearly 73% of the probes tested. Klenow/random primer-labeled targets resulted in an interaction with a complex mixture of 16S rRNA genes (used as the background) 3.7 times higher than the interaction of 45-mer targets with the same mixture. A 7-base-long dangling end sequence with perfect homology to another single-stranded background DNA sequence was sufficient to produce a cross-hybridization signal that was as strong as the signal obtained by the probe-target duplex itself. Gibbs free energy between the target and a well-defined background was found to be a better indicator of hybridization signal intensity than the sequence or length of the dangling end alone. The dangling end (Gibbs free energy of -7.6 kcal/mol) was found to be significantly more prone to target-background interaction than the surface-proximal tail (Gibbs free energy of -64.5 kcal/mol). This study underlines the need for careful target preparation and evaluation of signal intensities for diagnostic arrays using 16S rRNA and other gene targets due to the potential for target interaction with a complex background.

Bacteria↗
PubMed1990

Oxidation products of caffeic acid as model substances for the antigonadotropic activity of plant extracts.

Phenolic plant constituents exert antigonadotropic activity following an oxidation. The resulting complex mixture of mostly instable products impedes the elucidation of the various oxidation steps as well as the mode of antigonadotropic action. Thus caffeic acid was chosen as a single model phenolic to facilitate the interpretation. The oxidation of caffeic acid with KMnO4 as well as with polyphenoloxidase leads to the instable caffeic acid o-quinone as the first oxidation product. Following the initial oxidation, a number of products was indicated via HPLC. Two of them were isolated and characterized as oligomers of caffeic acid, one of them with phenolic, acid and, quinoic structural components and a relative molecular mass similar to caffeic acid tetramer. It was shown that caffeic acid quinone cannot be the antigonadotropically active principle. Correspondingly, the isolated oxidation products exhibit pronounced antigonadotropic activity. It could be proved that oxidation products of caffeic acid bind to PMSG, forming PMSG-inhibitor-complexes. In such complexes the gonadotropic activity of PMSG is completely abolished.

Animals↗
PubMed1995

Role of urinary physiology and chemistry in bladder carcinogenesis.

Urine is a complex mixture of numerous substances, only some of which are described above. Literally thousands of substances have been identified in normal urine, including a variety of ions, non-ionic substances and macromolecules. Their presence and concentrations are highly variable, dependent on fluid intake and on nutritional, physiological and biochemical influences. Marked diurnal variations exist. Methodologies involved in the collection and analysis of these components can greatly influence the interpretation of the results. The influence of these various parameters in the urine on bladder carcinogenicity can be either direct or indirect. A major difficulty in studying this aspect of urothelial carcinogenesis is that it is essentially impossible to alter only one variable in the urine at a time. Alteration of any one variable results in physiological alteration of several other of the constituents in the urine. In addition, the processes involved in urothelial carcinogenesis frequently involve a complex interaction of multiple variables, such as volume, osmolality, cationic concentration, anionic concentration, quantitative and qualitative differences in protein, and generation of precipitate, crystals or calculi. Thus, it is likely that the actual mechanisms involved in the carcinogenic process with many of these chemicals, particularly those that are non-genotoxic, will involve a complex interaction of several constituents of the urine. Although this poses a formidable obstacle to our understanding in experimental situations as well as in extrapolating to humans, the role of specific factors appears to be discernible and should offer insight into the risk assessment process (Cohen and Ellwein, 1991 a,b and 1992).

Animals↗
PubMed2001

Comparison of PowerPlex 16, PowerPlex1.1/2.1, and ABI AmpfISTR Profiler Plus/COfiler for forensic use.

AIM: Several amplification and detection formats for the analysis of short tandem repeat loci are readily available to the forensic laboratory. Careful consideration must be given to the throughput, sensitivity, concordance, data interpretation, facility requirements, and costs of operation. The Pennsylvania State Police DNA Laboratory sought to establish that of any of the amplification or detection formats generally used in the United States generates concordant results and that the use of several formats within one laboratory provides a solution to the interpretation of difficult evidentiary samples. METHODS: Validation work consisting of sensitivity, precision, mixture, and substrate studies was performed by use of each of three detection formats (ABI Prism(r)310 Genetic Analyzer, ABI Prism(r)377 DNA Sequencer, and the Hitachi FMBIO(r)II Fluorescent Scanner) and three amplification systems (GenePrint(r) PowerPlex 16, GenePrint(r) PowerPlex 1.1/2.1, and AmpflSTR ProfilerPlus/COfiler). The results generated in each of the formats were compared, along with the problems incurred. RESULTS: All allele calls were concordant, with the exception of primer region variants, and all detection systems were sensitive and reliable. Even with the use of multiple formats, a general protocol can be written with only one set of interpretation guidelines. CONCLUSION: National databases can be used with input data from any of these formats. The use of several detection formats allowed the forensic scientist to select a system, based on sample quality, quantity, and throughput requirements. Interpretation issues resulting from complex mixtures, degraded samples, rare microvariants, internal primer variants, unusual heterozygote ratios, above or below ladder alleles, and potential tri-alleles can be verified.

Criminology↗
PubMed2003

Mutagenicity, antioxidant potential, and antimutagenic activity against hydrogen peroxide of cashew (Anacardium occidentale) apple juice and cajuina.

Fresh and processed cashew (Anacardium occidentale) apple juice (CAJ) are among the most popular drinks in Brazil. Besides their nutritional benefits, these juices have antibacterial and antitumor potential. The chemical constituents of both the fresh juice and the processed juice (cajuina) were analyzed and characterized as complex mixtures containing high concentrations of vitamin C, various carotenoids, phenolic compounds, and metals. In the present study, these beverages exhibited direct and rat liver S9-mediated mutagenicity in the Salmonella/microsome assay with strains TA97a, TA98, and TA100, which detect frameshifts and base pair substitution. No mutagenicity was observed with strain TA102, which detects oxidative and alkylating mutagens and active forms of oxygen. Both CAJ and cajuina showed antioxidant activity as determined by a total radical-trapping potential assay. To test whether this antioxidant potential might result in antimutagenesis, we used a variation of the Salmonella/microsome assay that included pre-, co-, and posttreatment of hydrogen peroxide-exposed Salmonella typhimurium strain TA102 with the juices. CAJ and cajuina protected strain TA102 against mutation by oxidative damage in co- and posttreatments. The antimutagenic effects during cotreatment with hydrogen peroxide may be due to scavenging free radicals and complexing extracellular mutagenic compounds. The protective effects in posttreatment may be due to stimulation of repair and/or reversion of DNA damage. The results indicate that CAJ and cajuina have mutagenic, radical-trapping, antimutagenic, and comutagenic activity and that these properties can be related to the chemical constituents of the juices.

Anacardium↗
PubMed1990

Assignment of disulfide bonds in proteins by partial acid hydrolysis and mass spectrometry.

A new method is described for locating disulfide bonds in proteins which cannot be cleaved between half-cystinyl residues by enzymic methods, as is often the case for tightly coiled proteins, or for proteins in which half-cystinyl residues are not separated by residues required for enzymic cleavage. Partial acid hydrolysis of a model protein, hen egg-white lysozyme, produces a mixture of disulfide-containing peptides from which the disulfide connections may be deduced. The usefulness of a combination of HPLC, fast atom bombardment mass spectrometry, and computer-assisted analysis to identify disulfide-containing peptides present in the partial acid hydrolysate of the model protein is demonstrated. Chromatographic fractions of the hydrolysate were analyzed by mass spectrometry before and after chemical reduction of the disulfide bonds to determine the molecular weights of disulfide-containing peptides. Computer-assisted analysis was then used to relate the molecular weights of these peptides to specific segments of the protein from which the disulfide connectivities could be determined. Partial acid hydrolysis of proteins, which is attractive because it proceeds relatively independent of the amino acid sequence and structure, and because disulfide interchange is unlikely to occur in dilute acid, has become practical because disulfide-containing peptides present in complex mixtures can be identified rapidly and definitively by this method.

Acids↗
PubMedDate not supplied

Development of an immunomagnetic assay system for rapid detection of bacteria and leukocytes in body fluids.

Immunomagnetic (IM) separation and concentration of specific target ligands or particles, such as bacteria or leukocytes, from complex mixtures, such as bone marrow, blood and other body fluids, is now a widely accepted technique. IM methodologies require high affinity antibodies or other receptors, but are potentially as effective as density gradient separations. Thus, a computer-controlled first-generation immunomagnetic assay system (IMAS) biodetector is being developed for clinical diagnostics. This system is fully automated and affords the advantage of rapid flow-through capture of all types of magnetic beads (MBs) and obviates operator contact with body fluid samples during the collection and analysis phases. In the present work, biotinylated capture antibodies were bound to streptavidin-coated MBs for capture of E. coli O157:H7, T cells and T cell subsets. Samples were automatically vortex mixed with antibody-coated MBs, stained with an acridine dye or fluorescent antibody and collected in a specially designed flow cell containing multiple steel pins, which concentrate external magnetic field lines. IM complexes were rapidly (within minutes), separated from their media in the magnetic field. Magnetically captured particles were automatically rinsed in the flow cell to remove unwanted materials and detection was achieved via a flow-through fluorimeter. Samples can be subsequently captured on a microbiological filter for microscopic visualization and image analysis. Preliminary results demonstrate that rapid detection of target bacteria and leukocytes at low concentrations in body fluids is possible with a total assay time under 1 h. This IM technology has many other potential clinical, industrial and environmental monitoring applications.

Animals↗
PubMed2005

Effect of antioxidant-enriched diets on glutathione redox status in tissue homogenates and mitochondria of the senescence-accelerated mouse.

The main purpose of this study was to investigate whether consumption of diets enriched in antioxidants attenuates the level of oxidative stress in the senescence-accelerated mouse (SAM). In separate and independent studies, two different dietary mixtures, one enriched with vitamin E, vitamin C, L-carnitine, and lipoic acid (Diet I) and another diet including vitamins E and C and 13 additional ingredients containing micronutrients with bioflavonoids, polyphenols, and carotenoids (Diet II), were fed for 8 and 10 months, respectively. The amounts of glutathione (GSH) and glutathione disulfides (GSSG) and GSH:GSSG ratios were determined in plasma, tissue homogenates, and mitochondria isolated from five different tissues of SAM (P8) mice. Both diets had a reductive effect in plasma; however Diet I had relatively little effect on the glutathione redox status in tissue homogenates or mitochondria. Remarkably, Diet II caused a large increase in the amount of glutathione and a marked reductive shift in glutathione redox state in mitochondria. Overall, the effects of Diet II were tissue and gender specific. Results indicated that the glutathione redox state in mitochondria and tissues can be altered by supplemental intake of a relatively complex mixture of dietary antioxidants that contains substances known to induce phase 2 enzymes, glutathione, and antioxidant defenses. Whether corresponding attenuations occur in age-associated deleterious changes in physiological functions or life span remains unknown.

Aging↗
PubMed1994

Site-specific enzymatic hydrolysis of taxanes at C-10 and C-13.

The production of large amounts of paclitaxel for use as an anticancer treatment has been a challenging problem because of the low concentration of the compound in yew trees and its occurrence as part of a mixture of other taxanes. Two novel enzymes were isolated to facilitate the production of 10-deacetylbaccatin III, a precursor used for semisynthesis of paclitaxel and analogs. A strain of Nocardioides albus (SC13911) was isolated from soil and found to produce an extracellular enzyme that specifically removed the C-13 side chain from paclitaxel, cephalomannine, 7-beta-xylosyltaxol, 7-beta-xylosyl-10-deacetyltaxol, and 10-deacetyltaxol. The enzyme was purified to near homogeneity to give a polypeptide with 47,000 M(r) on a sodium dodecyl sulfate gel. A strain of Nocardioides luteus (SC13912) isolated from soil was found to produce an intracellular 10-deacetylase that removed the 10-acetate from baccatin III and paclitaxel. The 10-deacetylase was purified to give a polypeptide with 40,000 M(r) on a sodium dodecyl sulfate gel. Treatment of extracts prepared from a variety of yew cultivars with the C-13-deacylase and C-10-deacetylase converted a complex mixture of taxanes primarily to 10-deacetylbaccatin III and increased the amount of this key precursor by 4-24 times.

Bridged Bicyclo Compounds↗
PubMed1984

Role of mobile phase components for multi-functional solutes in silica gel liquid-solid chromatography. Resolution of protected deoxyribonucleotide derivatives oligomer synthesis.

To improve the resolution of a given sample mixture in liquid-solid chromatography, the characteristics of various components in the mobile phase were determined with a mixture of closely related compounds associated with DNA oligomer synthesis. Water (S0) was added so as to reduce peak tailing efficiently, but in amounts that would not significantly diminish retentivity in the silica gel column. The role of the stronger solvents, such as 1-propanol (S1) and dioxane (S2), in n-hexane (W) as diluent was quantitatively evaluated to control the retentivity. A linear correlation was found between the logarithms of the capacity ratios and molar concentration of the stronger component in the ternary solvent mobile phase. The selectivity of two stronger solvents was incorporated into the phase system to increase the resolution function for four given samples. A quaternary solvent system (W + S1 + S2 + S0) was prepared by integrating the characteristics of all the components, as determined by regression analysis. The multi-component phase system led to a high degree of resolution. This effective procedure was found suitable for analytical and preparative purposes in the resolution of various complex mixtures.

Chemical Phenomena↗
PubMed1996

Rapid approach for sequencing neutral oligosaccharides by exoglycosidase digestion and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.

A new way of combining exoglycosidase digestion with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI/TOF-MS) is described which permits the structural characterization of underivatized oligosaccharides on low picomole amounts of starting material. The key feature of the new approach is that an oligosaccharide sample can be recovered after a MALDI experiment and a series of sequential exoglycosidase digestions can be carried out on that sample within a single working day. The following steps are involved: (i) recording a molecular mass profile of the starting material by MALDI/TOF-MS using a mixture of 2,5-dihydroxybenzoic acid and 1-hydroxyisoquinoline as the matrix; (ii) recovery of the sample from the target and removal of the matrix by droplet dialysis (molecular mass cut-off 500 Da); (iii) exoglycosidase digestion in a volume of 1 microliter; (iv) removal of the incubation buffer by droplet dialysis; (v) removal of the enzyme by absorption on a Nafion membrane and (vi) start of the next cycle from (i). The method exhibits the following advantages over traditional oligosaccharide sequencing techniques: (i) analysis of digestion products by MALDI/TOF-MS is much faster than by chromatographic techniques; (ii) no derivatization of the analyte is required; (iii) exoglycosidase digestions work faster in small reaction volumes because substrate concentrations are closer to the Km of the enzyme; (iv) advanced sample handling techniques ensure reduced losses and (v) no sample splitting is needed for analysis and therefore the sensitivity of the overall method is increased. The method is illustrated by the analysis of isolated glycans and complex mixtures derived from chicken ovalbumin and human immunoglobulin G.

Animals↗
PubMed1984

Structural analysis of heparin by methylation and g.l.c.-m.s.: preliminary results.

Heparin is a complex mixture of polysaccharides differing in biological activity and structure, and attempts to relate this activity to structure have suffered, owing to a lack of sufficiently sensitive and specific analytical methods. Application of methylation analysis to determination of the structure of heparin is described. Carboxyl-reduced heparin was converted into its pyridinium salt, this was dissolved in Me2SO, and free OH and NH groups were methylated with dimethylsulfinyl anion. Sulfate groups were removed by solvolysis, and after dialysis, the polymer was acetylated and depolymerized by acetolysis. The resulting monosaccharides were converted into alditol acetates, which were separated by capillary, gas-liquid chromatography, and identified by both electron impact and chemical ionization mass spectrometry. Seventeen different monosaccharides were identified in the hydrolyzate. All of the expected internal hexosaminyl and glycosyluronic residues were identified. Although several sugars were identified as nonreducing termini, only a hexosamine 6-sulfate was identified as a reducing-terminus sugar. The results indicate that methylation analysis of heparins and other complex, sulfated glycosaminoglycans is feasible.

Chemical Phenomena↗
PubMed1999

A molluscan peptide alpha-amidating enzyme precursor that generates five distinct enzymes.

Mechanisms underlying the specificity and efficiency of enzymes, which modify peptide messengers, especially with the variable requirements of synthesis in the neuronal secretory pathway, are poorly understood. Here, we examine the process of peptide alpha-amidation in individually identifiable Lymnaea neurons that synthesize multiple proproteins, yielding complex mixtures of structurally diverse peptide substrates. The alpha-amidation of these peptide substrates is efficiently controlled by a multifunctional Lymnaea peptidyl glycine alpha-amidating monooxygenase (LPAM), which contains four different copies of the rate-limiting Lymnaea peptidyl glycine alpha-hydroxylating monooxygenase (LPHM) and a single Lymnaea peptidyl alpha-hydroxyglycine alpha-amidating lyase. Endogenously, this zymogen is converted to yield a mixture of monofunctional isoenzymes. In vitro, each LPHM displays a unique combination of substrate affinity and reaction velocity, depending on the penultimate residue of the substrate. This suggests that the different isoenzymes are generated in order to efficiently amidate the many peptide substrates that are present in molluscan neurons. The cellular expression of the LPAM gene is restricted to neurons that synthesize amidated peptides, which underscores the critical importance of regulation of peptide alpha-amidation.

Amino Acid Sequence↗
PubMed2001

Selection of a plant-bacterium pair as a novel tool for rhizostimulation of polycyclic aromatic hydrocarbon-degrading bacteria.

We developed a novel procedure for the selection of a microbe-plant pair for the stable and efficient degradation of naphthalene. Based on the rationale that root exudate is the best nutrient source available in soil, the grass (Lolium multiflorum) cultivar Barmultra was selected because of its abilities to produce a highly branched root system, root deeply, and carry a high population of Pseudomonas spp. bacteria on its roots. Starting with a mixture of total rhizobacteria from grass-like vegetation collected from a heavily polluted site and selecting for stable naphthalene degradation as well as for efficient root colonization, Pseudomonas putida strain PCL1444 was isolated. The strain's ability to degrade naphthalene was shown to be stable in the rhizosphere. Moreover, it had superior root-colonizing properties because, after the inoculation of grass seedlings, it appeared to colonize the root tip up to 100-fold better than the efficient root colonizer Pseudomonas fluorescens WCS365. Strain PCL1444 uses root exudate as the dominant nutrient source because the presence of grass seedlings in soil results in up to a 10-fold increase of PCL1444 cells. Moreover, the root colonized by strain PCL1444 was able to penetrate through an agar layer, resulting in the degradation of naphthalene underneath this layer. In addition, the inoculation of grass seeds or seedlings with PCL1444 protected them against naphthalene phytotoxicity. Finally, this plant-microbe combination appeared able to degrade naphthalene from soil that was heavily polluted with a complex mixture of polycyclic aromatic hydrocarbons. To our knowledge, this is the first time that a naturally occurring bacterium has been selected for the combination of the abilities to degrade a pollutant and colonize plant roots. We suggest that the principle described here, to select a bacterium which combines efficient root colonization with a beneficial activity, also can be used to improve the selection of other more efficient plant-bacterium pairs for beneficial purposes such as biocontrol, biofertilization, and phytostimulation.

Biodegradation, Environmental↗