A novel EDTA-degrading Pseudomonas sp.

A bacterial strain LPM-410 capable of utilizing ethylenediaminetetraacetate (EDTA) as the sole source of energy, carbon, and nitrogen was isolated from sewage sludge and identified as a Pseudomonas sp. on the basis of its phenotypic characteristics. Suspensions of exponential-phase cells degraded EDTA, Mg–, Ca–, Ba–, and Mn–EDTA at constant specific rates ranging from 0.363 to 0.525 mmol EDTA/(g cells h). The more stable chelate, Zn–EDTA, was degraded at a lower rate (0.195 ± 0.030 mmol EDTA/(g cells h)), and here was no degradation of Co–, Cu–, Pb–, and Fe(III)–EDTA.     

Metabolism of benzalphthalide by Pseudomonas sp.

A Pseudomonas sp. degraded benzalphthalide to o-phthalate and benzoate. A tentative pathway for the metabolism of benzalphthalide in this Pseudomonas sp. is proposed on the basis of isolated metabolites, oxygraphic assay and enzymatic studies.     

Autotrophic growth and inorganic sulphur compound oxidation by Sulfolobus sp. in chemostat culture

Sulfolobus strain LM was grown in tetrathionate and thiosulphate-limited continuous culture. CO₂ limitation resulted in a decrease of the steady-state biomass and an increase in the specific rate of thiosulphate oxidation so that substrate did not accumulate in the medium. The initial step in thiosulphate utilization appeared to be its conversion to tetrathionate. The affinity for tetrathionate oxidation appeared to increase with prolonged continuous culture giving an apparent K _m of about 6 M tetrathionate, a higher affinity than for thiosulphate oxidation and in the same range as values observed with acidophilic, sulphur-oxidizing eubacteria.     

Role of oxygen in the utilization of phenol by Pseudomonas CF600 in continuous culture

The dissolved oxygen (DO) level is the key factor which decides the rate of degradation of the organic load in aerobic growth conditions. In this study the role of DO levels on the utilization of phenols has been reported using the continuous culture system. A phenol-utilizing strain, Pseudomonas CF600 has been used as a model. Its phenol-degrading capacity was studied using continuous cultivation for a period of 60 days. The bioreactor was kept at a dilution rate of 0.006 h^–1 with DO levels maintained at 2, 3, and 4 ppm keeping all the other cultivation conditions constant. Physiological variations under the cultivation conditions were studied by monitoring off-line phenol utilization and respirometric analysis of harvested culture against different substrates. It was observed that the accumulation of 2-hydroxymuconate semialdehyde (HMS), an intermediate in the phenol degradation pathway, depends on the DO level. The maximum level of HMS in the medium observed was 3.92 M when DO was maintained at 2 ppm whereas with 3 ppm of DO, HMS level was below 0.4 M. Oxygen uptake data of the cells harvested from cultures grown at different DO levels showed that the uptake was highest at 3 ppm DO for all the substrates tried. When phenol was used as substrate, the oxygen uptake rate was 42.66, 66.36 and 35.55 nM/min/mg dry weight of cells at 4, 3 and 2 ppm DO respectively. Results show that DO levels influence the rate of phenol utilization in Pseudomonas CF600.     

Degradation of carbazole and its derivatives by a Pseudomonas sp.

Carbazole, carbazoles with monomethyl or dimethyls substituted on different positions (C₁-carbazoles or C₂-carbazoles), and benzocarbazoles, as toxic and mutagenic components of petroleum and creosote contamination, were biodegradable by an isolated bacterial strain Pseudomonas sp. XLDN4-9. C₁-carbazoles were degraded in preference to carbazole and C₂-carbazoles. The biodegradation of C₁-carbazoles or C₂-carbazoles was influenced by the positions of methyl substitutions. Among C₁-carbazole isomers, 1-methyl carbazole was the most susceptible. C₂-carbazole isomers with substitutions on the same benzo-nucleus were more susceptible at a concentration of less than 3.4 μg g⁻¹ petroleum, especially when harboring one substitution on position 1. In particular, 1,5-dimethyl carbazole was the most recalcitrant dimethyl isomer.     

Conversion of substituted naphthalenesulfonates by Pseudomonas sp. BN6

The range of substituted naphthalenesulfonates which are metabolized by Pseudomonas sp. BN6 were investigated. Resting cells from strain BN6 oxidized 1- and 2-naphthalenesulfonate, 1-hydroxynaphthalene-2-sulfonate, 2,6-naphthalenedisulfonate and all monosulfonated naphthalene-2-sulfonates which carry one or two substitutents in the positions 4-, 5-, 6-, 7- or 8- of the naphthalene ring-system. With the exception of (substituted) 4- or 5-amino- and 4-hydroxynaphthalene-2-sulfonates these compounds were converted to the corresponding salicylates. Strain BN6 did not oxidize substituted naphthalene-1-sulfonates, 3-substituted naphthalenesulfonates and substituted naphthalenedisulfonates. Turnover of 4-amino- or 4-hydroxynaphthalene-2-sulfonates resulted in the accumulation of the corresponding naphthoquinones in the culture medium. Thus, degradation of 4-amino- and 4-hydroxynaphthalenesulfonates was restricted by the rapid autoxidation of the substituted 1,2-dihydroxynaphthalenes formed as metabolites. Catabolic activities of strain BN6 for naphthalenesulfonates were induced by salicylate, 3- or 6-hydroxysalicylate, and 3-, 4- or 5-aminosalicylate but not by 4- and 5-hydroxysalicylate. All naphthalenesulfonates that were not converted into the corresponding salicylates, were found to be inefficient as effectors. It was therefore concluded that (substituted) salicylates are the inducers of the relevant enzymes. The degradation of 2-naphthalene-sulfonate by a pure culture of strain BN6 was prevented by the toxicity of the dead-end product salicylate. Substituted salicylates were less toxic and allowed growth of strain BN6 in axenic culture with various substituted naphthalenesulfonates.Abbreviations AB aminobenzoate - ANS aminonaphthalenesulfonate - DHN dihydroxynaphthalene - DHNC dihydroxynaphthalene-carboxylate - DHNDO 1,2-dihydroxynaphthalene dioxygenase - HBPA 2-hydroxybenzalpyruvate aldolase - HNS hydroxynaphthalenesulfonate - HS hydroxysalicylate - Ind-C indolecarboxylate - Ind-S indolesulfonate - MANS N-methylaminonaphthalenesulfonate - NC naphthalenecarboxylate - NDS naphthalenedisulfonate - NQ naphthoquinone - NS naphthalenesulfonate - NSDO naphthalenesulfonate dioxygenase - R_t retention time - SADH salicylaldehyde dehydrogenase - THN trihydroxynaphthalene (hydroxy-1,2-dihydroxynaphthalene)     

Phenanthrene mineralization by Pseudomonas sp. UG14

A phenanthrene-mineralizing Pseudomonas sp., designated UG14, was isolated from creosote-contaminated soil. It contained two plasmids, of approximately 77 kb and 76 kb, the smaller of which contained DNA sequences that hybridized with probes specific for ndoB and xylE, genes involved in catabolism of aromatic hydrocarbons. At initial phenanthrene concentrations of 10, 50, 200 and 1000 mg/l broth, 27%, 19%, 7.7% and 3.3%, respectively, of the [9-¹⁴C]phenanthrene was recovered as ¹⁴CO₂ after 36 days' incubation at 30°C. Most ¹⁴C-label was converted to a water-soluble metabolite tentatively identified as 1-hydroxy-2-naphthoic acid. Rhamnolipid biosurfactants produced by P. aeruginosa UG2 enhanced mineralization of 50 mg phenanthrene/l by Pseudomonas sp. UG14. With the biosurfactant at 0, 25 and 250 mg rhamnose equivalents/l, 6.5%, 8.2% and 9.8%, respectively, of the phenanthrene was mineralized after 35 days.M.A. Providenti, H. Lee and J.T. Trevors are with the Department of Environmental Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada; C.W. Greer is with the National Research Council Canada, Biotechnology Research Institute, 6100 Royalmount Ave, Montreal, Quebec, H4P 2R2, Canada.     

Cloning,expression and characterization of a beta-agarase gene from a marine bacterium,Pseudomonas sp. SK38

A gene (pagA) encoding -agarase from Pseudomonas sp. SK38 was cloned and expressed in Escherichia coli. The structural gene consists of 1011 bp encoding 337 amino acids with a predicted molecular weight of 37326 and has a signal peptide of 18 amino acids. The deduced amino acid sequence showed 57% and 58% homology to -agarase from Pseudoalteromonas atalntica and Aeromonas sp., respectively. The recombinant enzyme was purified and biochemically characterized. The enzyme had maximum activity at pH 9 and 30 °C. It was stable at pHs from 8 to 9 and below 37 °C.     

The induction and repression of benzene and catechol oxidizing capacity of Pseudomonas putida ML2 studied in perturbed chemostat culture

The oxidation of catechol, an intermediate in benzene catabolism, was studied using transient variations in dissolved oxygen tension (DOT) when a succinate limited steady state culture of Pseudomonas putida ML2 was perturbed with a pulse of another substrate. A model was developed and tested for the effect of fluctuations in oxidizing enzyme activity on DOT. It was found that the rate of induction of catechol oxidizing enzymes was independent of dilution rate up to a relative growth rate /_max of 0.75. Only at higher dilution rates was catabolite repression observed.Abbreviations DOT dissolved oxygen tension - K _L a gas transfer coefficient - specific growth rate - _max maximum specific growth rate - K_s substrate saturation constant     

Evaluation of pentachlorophenol-degrading potentiality of Pseudomonas sp. in a soil microcosm

Pseudomonas sp. strain IST103 obtained from a stable consortium was capable of degrading pentachlorophenol (PCP) as sole carbon and energy source. The PCP-degrading potentiality of the strain was determined by growth of bacteria in culture medium, utilization of PCP by high performance liquid chromatography (HPLC), chloride release and ring cleavage. The strain was applied in two set of soil microcosms containing 20 and 40% moisture, each having different concentrations, 0, 10, 100, 500, and 1000 mg/l, of PCP. The result showed significant utilization of PCP (77% in 45 days) and higher growth of bacterial strain when PCP was applied in 100 mg/l concentration at 40% moisture. Inhibitory effects on the growth of bacterial strain were seen in 500 and 1000 mg/l concentration.     

Utilization of the cyanobacteria Anabaena sp. ATCC 33047 in CO2 removal processes

In this paper the utilization of the cyanobacteria Anabaena sp. in carbon dioxide removal processes is evaluated. For this, continuous cultures of this strain were performed at different dilution rates; alternatives for the recovery of the organic matter produced being also studied. A maximum CO₂ fixation rate of 1.45 g CO₂ L⁻¹ day⁻¹ was measured experimentally, but it can be increased up to 3.0 g CO₂ L⁻¹ day⁻¹ outdoors. The CO₂ is mainly transformed into exopolysaccharides, biomass representing one third of the total organic matter produced. Organic matter can be recovered by sedimentation with efficiencies higher than 90%, the velocity of sedimentation being 2 · 10⁻⁴ s⁻¹. The major compounds were carbohydrates and proteins with productivities of 0.70 and 0.12 g L⁻¹ day⁻¹, respectively. The behaviour of the cultures of Anabaena sp. has been modelized, also the characteristics parameters requested to design separation units being reported. Finally, to valorizate the organic matter as biofertilizers and biofuels is proposed.     

Production of a novel bioflocculant by fed-batch culture of Citrobacter sp.

Production of a novel bioflocculant by a fed-batch culture of Citrobacter sp. TKF04 was investigated using acetic acid as a sole carbon source. Synthesis of the bioflocculant was favored by dissolved O₂ tension at 20% of air saturation and C/N ratio (mol acetic acid/mol ammonium) of 10:1 in the feed solution. Under optimal conditions, 4.6 g crude bioflocculant per liter broth was produced, whose flocculating activity was 22 300 units. This activity was 9 times higher than that of the control (only acetic acid was supplied).     

Treponema succinifaciens sp. nov., an anaerobic spirochete from the swine intestine

The morphology, the general physiological characteristics, and the energy-yielding metabolism of an obligately anaerobic spirochete isolated from the colon of a swine were studied. Electron microscopy showed that the helical spirochetal cells possessed an outer sheath, a protoplasmic cylinder, and 4 periplasmic fibrils in a 2-4-2 arrangement. The spirochete grew in an atmosphere of N₂ in prereduced media containing a carbohydrate, NaHCO₃, rumen fluid, yeast extract, peptone, l-cysteine, and inorganic salts. The spirochete fermented carbohydrates and required substrate amounts of CO₂ (HCO ₃ ^- ) for growth. Amino acids were not fermented. Major fermentation products of cells growing with glucose as the substrate and in the presence of CO₂ were acetate, formate, succinate, and lactate. Small amounts of 2,3-butanediol, pyruvate, and acetoin were also formed. Determinations of enzymatic activities in cell extracts, and of radioactivity in products formed by growing cells from [1-¹⁴C]glucose, indicated that this sugar was dissimilated to pyruvate via the Embden-Meyerhof pathway. The spirochetes used a coliform-type clastic reaction to metabolize pyruvate. Determinations of radioactivity in products formed from [¹⁴C]NaHCO₃ indicated that CO₂ was assimilated and used in succinate production. The guanine+cytosine content of the DNA was 36 mol%. This study indicates that this intestinal spirochete represents a new species of Treponema. It is proposed that the new species be named Treponema succinifaciens.Abbreviations cpm counts per minute - DTT dithiothreitol - EM Embden-Meyerhof - GC guanine plus cytosine - IgG immunoglobulin G - PC protoplasmic cylinder - PF periplasmic fibrils (axial fibrils) - OS outer sheath     

Growth,N2 fixation and photosynthesis in a cyanobacterium,Trichodesmium sp., under Fe stress

Trichodesmium sp., isolated from the Great Barrier Reef lagoon, was cultured in artificial seawater media containing a range of Fe concentration. Fe additions stimulated growth, N₂ fixation, cellular chlorophyll a content, light-saturated chlorophyll a-specific gross photosynthetic capacity (P_m ^chla) and the dark respiration rate (R_d ^chla). Cell yields only doubled for 9 nM Fe relative to zero added Fe, whereas N₂ fixation increased 11-fold considerably for 450 nM Fe. The results suggest that N₂ fixation of Trichodesmium is more sensitive to Fe limitation than are the cell yields.     

Characterization of a thermophilic sulfur oxidizing enrichment culture dominated by a Sulfolobus sp. obtained from an underground hot spring for use in extreme bioleaching conditions

A thermoacidophilic elemental sulfur and chalcopyrite oxidizing enrichment culture VS2 was obtained from hot spring run-off sediments of an underground mine. It contained only archaeal species, namely a Sulfolobus metallicus-related organism (96% similarity in partial 16S rRNA gene) and Thermoplasma acidophilum (98% similarity in partial 16S rRNA gene). The VS2 culture grew in a temperature range of 35–76°C. Sulfur oxidation by VS2 was optimal at 70°C, with the highest oxidation rate being 99 mg S⁰ l⁻¹ day⁻¹. At 50°C, the highest sulfur oxidation rate was 89 mg l⁻¹ day⁻¹ (in the presence of 5 g Cl⁻ l⁻¹). Sulfur oxidation was not significantly affected by 0.02–0.1 g l⁻¹ yeast extract or saline water (total salinity of 0.6 M) that simulated mine water at field application sites with availability of only saline water. Chloride ions at a concentration above 10 g l⁻¹ inhibited sulfur oxidation. Both granular and powdered forms of sulfur were bioavailable, but the oxidation rate of granular sulfur was less than 50% of the powdered form. Chalcopyrite concentrate oxidation (1% w/v) by the VS2 resulted in a 90% Cu yield in 30 days.     

The structure of a pyoverdine from Pseudomonas sp. CFML 96.188 and its relation to other pyoverdines with a cyclic C-terminus

From Pseudomonas sp. CFML 96.188 a pyoverdine was isolated and its primary structure was elucidated by spectroscopic methods and degradation reactions. This strain is of interest as it accepts the structurally different pyoverdines from several other Pseudomonas strains. They all have in common as a specific structural feature a C-terminal cyclic substructure, the importance of which for the recognition of a pyoverdine at the cell surface of a given strain will be discussed.     

Short communication: Methylparathion degradation by Pseudomonas sp. A3 immobilized in sodium alginate beads

An organophosphate-degrading soil isolate of Pseudomonas sp. A3, immobilized at 5% (wet wt/v) cell mass in 3% (w/v) sodium alginate beads, detoxified 99% of 1 mm methylparathion in 48 h. The beads were re-usable for five batches, the sixth batch only giving 73% methylparathion removal.     

Degradation of hydrocarbons and biosurfactant production by Pseudomonas sp. strain LP1

Pseudomonas sp. strain LP1, an organism isolated on the basis of its ability to grow on pyrene, was assayed for its degradative and biosurfactant production potentials when growing on crude, diesel and engine oils. The isolate exhibited specific growth rate and doubling time of 0.304 days⁻¹ and 2.28 days, respectively on crude oil (Escravos Light). The corresponding values on diesel were 0.233 days⁻¹ and 2.97 days, while on engine oil, were 0.122 days⁻¹ and 5.71 days. The organism did not show significant biosurfactant production towards crude oil and diesel, but readily produced biosurfactant on engine oil. The highest Emulsification index (E₂₄) value for the biosurfactant produced by LP1 on engine oil was 80.33 ± 1.20, on day 8 of incubation. Biosurfactant production was growth-associated. The surface-active compound which exhibited zero saline tolerance had its optimal activity at 50°C and pH 2.0.     

Mixotrophic and heterotrophic growth of Beggiatoa alba in continuous culture

Beggiatoa alba strain B18LD was grown in continuous culture under heterotrophic conditions on acetate or acetate and asparagine and under mixotrophic conditions on acetate plus either 1 mM sodium sulfide or 1 mM sodium thiosulfate. Considerable differences were observed between the yields and the cell compositions of heterotrophic and mixotrophic cultures at all dilution rates tested. The dry weight yield per gram acetate utilized was approximately three times higher in the acetate-sulfide mixotrophic culture than in the acetate heterotrophic culture, whereas the poly--hydroxybutyric acid and carbohydrate contents were much higher in the heterotrophic cultures. The high yields (0.52–0.75, corrected for the weight of the sulfur) obtained with the mixotrophic cultures imply that the acetate was utilized mainly for biosynthesis. Thus, the oxidation of sulfide supplied energy. The addition of catalase to the chemostat cultures increased yields slightly, but it was insufficient to explain the differences between the heterotrophic and the mixotrophic cultures.     

Biosurfactant production and hydrocarbon-degradation by halotolerant and thermotolerant Pseudomonas sp.

A hydrocarbon degrading and biosurfactant producing, strain DHT2, was isolated from oil-contaminated soil. The organism grew and produced biosurfactant when cultured in variety of substrates at salinities up to 6 g l⁻¹ and temperatures up to 45°C. It was capable of utilizing crude oil, fuels, alkanes and PAHs as carbon source across the wide range of temperature (30–45°C) and salinity (0–6%). Over the range evaluated, the salinity and temperature did not influence the degradation of hydrocarbon and biosurfactant productions. Isolate DHT2 was identified as Pseudomonas aeruginosa by analysis of 16S rRNA sequences (100% homology) and biochemical analysis. PCR and DNA hybridization studies revealed that enzymes involved in PAH metabolism were related to the naphthalene dioxygenase pathway. Observation of both tensio-active and emulsifying activities indicated that biosurfactants were produced by DHT2 during growth on both, water miscible and immiscible substrates, including PAH. The biosurfactants lowered the surface tension of medium from 54.9 to 30.2 dN/cm and formed a stable emulsion. The biosurfactant produced by the organism emulsified a range of hydrocarbons with hexadecane as best substrate and toluene was the poorest. These findings further indicate that the isolate could be useful for bioremediation and bio-refining application in petroleum industry.