Biodegradation of crude oil by soil microorganisms in the tropic

Constitutive expression of foreign glutamate dehydrogenase in Rhizobium etli inhibits bean plant nodulation (A. Mendoza, A. Leija, E. Martínez-Romero, G. Hernández, and J. Mora. Mol. Plant-Microbe Interact. 8:584-592, 1995). Here we report that this inhibition is overcome when controlling gdhA expression by NifA, thus delaying the GDH activity onset after nodule establishment. Expression of gdhA modifies the nitrogen partitioning inside the bacteroid, where newly synthesized ammonia is preferentially incorporated into the amino acid pool instead of being exported to the infected cells. As a consequence, the fixed nitrogen transport to the leaves, measured as the ureides content in xylem sap, is significantly reduced. Nitrogenase activity, although not nifHDK expression, is significantly reduced in bacteroids expressing gdhA, probably due to the utilization of energy and reducing power for nitrogen assimilation. Here we show that ammonia assimilation inside R. etli bacteroids is active, albeit at low levels, and when enhanced is deleterious to the symbiotic performance. This leads us to believe that further reduction of the basal nitrogen metabolism in the bacteroid might stimulate the nitrogenase activity and increase the nitrogen supply to the plant.     

Cellulolytic activity of aerobic soil actinomycetes

The cellulolytic activity of several aerobic soil actinomycetes against insoluble cellulose and soluble cellulose derivatives (CMC-carboxymethylcellulose) was studied. From the soil, 8 actinomycete strains were isolated after enrichment growth and purification on the same synthetic medium. The actinomycete strains were able to degrade insoluble cellulose, with the production of cellobiose and various oligosaccharide intermediates as degradation products, indicating the random attack of the cellulose chain. The actinomycete strains showed also a great activity against soluble cellulose (CMC). The viscosity of CMC solutions decreased rapidly and was followed by an increase in reducing compounds. The degree of substitution of CMC solutions had an effect on the degradation by the actinomycetes. The degree of polymerization did not affect the rate of hydrolysis, however.     

Breakdown of the herbicide pyramin by micro-organisms of the soil (author's transl)

The herbicide Pyramin, which is employed in the cultivation of beets to combat broad-leaf weeds, contains the herbicidal substance 5-amino-4-chloro-2-phenyl-3 (2H) pyridazinone, abbreviated pyrazone. The breakdown of pyrazone in the soil was investigated and it was found that this substance disappears relatively quickly and that the dephenylated heterocycle of pyrazone 5-amino-4-chloro-3 (2H) pyridazinone is obtained as transformation product. It was possible to isolate bacteria, which grow on pyrazone as the only carbon source, from soil samples originating from different parts of the world. Four compounds are excreted during the cultivation of pyrazone-degrading bacteria in a pyrazone mineral salt medium. With the aid of the structure of these metabolites and enzymatic tests, a scheme for the bacterial breakdown of pyrazone is proposed.     

Isolation of soil actinomycetes on selective media with novobiocin

The diurnal intraocular pressure was measured in 14 eyes of patients with glaucoma while they were using no medication and compared to the diurnal pressures while they were using pilocarpine drops. During the 48 hour control period, the pressures measured every 3 hours by the non-contact tonometer had a mean value of 26 mm. Hg and a mean maximum diurnal variation of 18.5 mm. Hg. During the pilocarpine treatment period, the mean pressure and maximum diurnal variation dropped to 17 and 8.5 mm. Hg, respectively. The greatest pressure-lowering effect occurred between 9 A.M. and 6 P.M.     

Advanced Oxidation of Diuron by Photo-Fenton Treatment as a Function of Operating Parameters

Advanced oxidation of diuron in aqueous solution by photo-Fenton treatment was investigated by batch experiments. Effects of operating parameters, namely, the concentrations of pesticide (diuron), hydrogen peroxide (H2O2), and ferrous ion [Fe (II)] on oxidation of diuron were investigated by using Box-Behnken statistical experiment design and the response surface methodology. Diuron oxidation by photo-Fenton treatment was evaluated by determining the total organic carbon (TOC), diuron, and adsorbable organic halogen (AOX) removals. Concentration ranges of the reagents resulting in the highest level of diuron oxidation were determined. Diuron removal increased with increasing H2O2 and Fe (II) concentrations, up to a certain level. H2O2 concentration had a more profound effect than diuron and Fe (II) on removal of diuron, TOC, and AOX from the aqueous solution. Complete (100%) disappearance of diuron was achieved after a 15?min reaction period. However, 85% of diuron was mineralized after 240?min, indicating a low level of intermediate formation. Optimal H2O2/Fe (II)/diuron ratio resulting in maximum diuron (100%), TOC (85%), and AOX (100%) removals was found to be 267/36/25?(mg?L?1).     

Biodegradation of atrazine by Agrobacterium radiobacter J14a and use of this strain in bioremediation of contaminated soil

We examined the ability of a soil bacterium, Agrobacterium radiobacter J14a, to degrade the herbicide atrazine under a variety of cultural conditions, and we used this bacterium to increase the biodegradation of atrazine in soils from agricultural chemical distribution sites. J14a cells grown in nitrogen-free medium with citrate and sucrose as carbon sources mineralized 94% of 50 microgram of [14C-U-ring]atrazine ml-1 in 72 h with a concurrent increase in the population size from 7.9 x 10(5) to 5.0 x 10(7) cells ml-1. Under these conditions cells mineralized the [ethyl-14C]atrazine and incorporated approximately 30% of the 14C into the J14a biomass. Cells grown in medium without additional carbon and nitrogen sources degraded atrazine, but the cell numbers did not increase. Metabolites produced by J14a during atrazine degradation include hydroxyatrazine, deethylatrazine, and deethyl-hydroxyatrazine. The addition of 10(5) J14a cells g-1 into soil with a low indigenous population of atrazine degraders treated with 50 and 200 microgram of atrazine g-1 soil resulted in two to five times higher mineralization than in the noninoculated soil. Sucrose addition did not result in significantly faster mineralization rates or shorten degradation lag times. However, J14a introduction (10(5) cells g-1) into another soil with a larger indigenous atrazine-mineralizing population reduced the atrazine degradation lag times below those in noninoculated treatments but did not generally increase total atrazine mineralization.     

Biodegradation of phenols by the alga Ochromonas danica

The eukaryotic alga Ochromonas danica, a nutritionally versatile, mixotrophic chrysophyte, grew on phenol as the sole carbon source in axenic culture and removed the phenol carbon from the growth medium. Respirometric studies confirmed that the enzymes involved in phenol catabolism were inducible and that the alga oxidized phenol; the amount of oxygen consumed per mole of oxidized substrate was approximately 65% of the theoretical value. [U-14C]phenol was completely mineralized, with 65% of the 14C label appearing as 14CO2, approximately 15% remaining in the aqueous medium, and the rest accounted for in the biomass. Analysis of the biomass showed that 14C label had been incorporated into the protein, nucleic acid, and lipid fractions; phenol carbon is thus unequivocally assimilated by the alga. Phenol-grown cultures of O. danica converted phenols to the corresponding catechols, which were further metabolized by the meta-cleavage pathway. This surprising result was rigorously confirmed by taking the working stock culture through a variety of procedures to check that it was axenic and repeating the experiments with algal extracts. This is, as far as is known, the first definitive identification of the meta-cleavage pathway for aromatic ring degradation in a eukaryotic alga, though its incidence in other eukaryotes has been (infrequently) suggested.     

Biodegradation of cellulose acetate by Neisseria sicca

Bacteria capable of assimilating cellulose acetate, strains SB and SC, were isolated from soil on a medium containing cellulose acetate as a carbon source, and identified as Neisseria sicca. Both strains degraded cellulose acetate membrane filters (degree of substitution, DS, mixture of 2.8 and 2.0) and textiles (DS, 2.34) in a medium containing cellulose acetate (DS, 2.34) or its oligomer, but were not able to degrade these materials in a medium containing cellobiose octaacetate. Biodegradation of cellulose acetate (DS, 1.81 and 2.34) on the basis of biochemical oxygen demand reached 51 and 40% in the culture of N. sicca SB and 60 and 45% in the culture of N. sicca SC within 20 days. A decrease in the acetyl content of degraded cellulose acetate films and powder was confirmed by infrared and nuclear magnetic resonance analyses. After 10-day cultivation of N. sicca SB and SC, the number-average molecular weight of residual cellulose acetate decreased by 9 and 5%, respectively. Activities of enzymes that released acetic acid and produced reducing sugars from cellulose acetate were mainly present in the culture supernatant. Reactivity of enzymes for cellulose acetate (DS, 1.81) was higher than that for cellulose acetate (DS, 2.34).     

Biodegradation of phenols by a eukaryotic alga

A series of dental outpatients in Brazil was anonymously screened for HIV antibodies in whole unstimulated saliva with an immunoglobulin G antibody-capture enzyme-linked immunosorbent assay. Salivary HIV antibodies were detected in 40 patients in the control group who were known to be HIV-seropositive but were not detected in any of a series of 40 known HIV-seronegative patients in the control group, confirming the very high sensitivity and specificity of the immunoglobulin G antibody-capture enzyme-linked immunosorbent assay. Only one patient from 84 consecutive dental outpatients of unknown HIV serostatus who were examined anonymously for HIV by immunoglobulin G antibody-capture enzyme linked immunosorbent assay showed HIV positivity (1.2% of the population).     

Survival, metabolic activity and conjugative interactions of indigenous and introduced streptomycete strains in soil microcosms

Exocytosis of cortical granules in mouse eggs is required to produce the zona pellucida block to polyspermy. In this study, we examined the role of microfilaments and microtubules in the regulation of cortical granule movement toward the cortex during oocyte maturation and anchoring of cortical granules in the cortex. Fluorescently labeled cortical granules, microfilaments, and microtubules were visualized using laser-scanning confocal microscopy. It was observed that cortical granules migrate to the periphery of the oocyte during oocyte maturation. This movement is blocked by the treatment of oocytes with cytochalasin D, an inhibitor of microfilament polymerization, but not with nocodazole or colchicine, inhibitors of microtubule polymerization. Cortical granules, once anchored at the cortex, remained in the cortex following treatment of metaphase II-arrested eggs with each of these inhibitors; i.e., there was neither inward movement nor precocious exocytosis. Finally, the single cortical granule-free domain that normally becomes localized over the metaphase II spindle was not observed when the chromosomes become scattered following microtubule disruption with nocodazole or colchicine. In these instances a cortical granule-free domain was observed over each individual chromosome, suggesting that the chromosome or chromosome-associated material, and not the spindle, dictates the localization of the cortical granule-free domain.     

Determination of cereal herbicide residues in environmental samples by gas chromatography

Gas chromatographic analysis of cereal herbicide residues in water, soil, plant and air is reviewed. Herbicides widely used in spring and winter cereals, i.e., phenoxyacids, benzonitriles, ureas, triazines, dinitroanilines, chloroacetamides and thiocarbamates, are considered. The main procedures used in the residue analysis, extraction, clean-up, derivatization and gas chromatographic determination are summarized and discussed.     

Levels of the herbicide glyphosate in well water

The prognostic significance of tumour cell proliferation was investigated in a series of 418 gastric carcinomas using the monoclonal antibody MIB-1. Owing to strong intratumoural heterogeneity of MIB-1 expression three different proliferation indices (PIs) were determined in all carcinomas: (1) PImax in areas of maximal tumour cell proliferation, (2) PIrand in areas randomly distributed over the whole tumour. (3) PIfront in areas exclusively located at the tumour invasion front. There was a strong intertumoral heterogeneity with PImax ranging from 4.9% to 92.2%, PIrand ranging from 3.4% to 81.4% and PIfront ranging from 4.2% to 87.1%. The mean values were 51.3% +/- 19.7 for PImax, 34.2% +/- 18.3 for PIrand and 37.2% +/- 19.5 for PIfront. Whereas no statistically significant correlation could be found between proliferative activity and the clinicopathological parameters depth of invasion, lymph node involvement or grade of tumour differentiation, there was a positive correlation between a high proliferation index at the tumour invasion front (PIfront) and the presence of blood or lymphatic vessel invasion. No significant correlation could be demonstrated between the different proliferation indices and survival, even when different subgroups of patients were analysed separately. The present results suggest that the immunohistochemical evaluation of the proliferation activity has no predictive value for the prognosis of gastric cancer patients or the identification of subgroups of patients who may be at higher risk.     

Biodegradation of a synthetic lubricant by Micrococcus roseus

A bacterium that was able to utilize Emkarate 1550 (E1550), a synthetic lubricant ester, as the sole source of carbon was isolated. The isolate was tentatively identified as Micrococcus roseus. The components of the E1550 ester, octanoate, decanoate, and 1,1,1-tris(hydroxymethyl)propane (TMP), were detected in the culture medium of cells growing on the ester. The TMP tertiary alcohol accumulated during growth and was not utilized by this isolate. The detection of the components of the ester in the supernatant of cultures indicated that one of the first steps in its degradation was cleavage of the ester bonds. Esterase activity was significantly enhanced in cells grown on E1550 compared with esterase activity measured in cells grown on acetate.     

Biodegradation of anthracene by soil fungi. Groupe pour l'Etude du Devenir des Xénobiotiques dans l'Environnement (GEDEXE)

A selection of 39 strains of micromycetes known as good degraders of polychlorinated aromatic compounds, mostly isolated from soil and belonging to various taxonomic groups, have been investigated for anthracene degradation. Toxicity and consumption assays, first evaluated on solid media, have not shown any toxicity of anthracene (1-100 mg.L-1) towards fungi. Degradation of anthracene (10 mg.L-1) was then investigated in a liquid synthetic medium for 4 days and evaluated by HPLC. Among the 39 strains tested, 19 degraded anthracene at 50% or more. Zygomycetes appeared to be the most efficient group (mean degradation : 81%) while Melanconiales were the least efficient (mean: 14%). Among 19 efficient strains, 8 had not yet been reported in the literature: Cryphonectria parasitica, Ceriporiopsis subvermispora, Oxysporus sp., Cladosporium herbarum, Drechslera spicifera, Verticillium lecanii, Fusarium moniliforme var. subglutinans and Rhizopus arrhizus.     

Biodegradation of metal-EDTA complexes by an enriched microbial population

A mixed culture utilizing EDTA as the sole carbon source was isolated from a mixed inoculum of water from the River Mersey (United Kingdom) and sludge from an industrial effluent treatment plant. Fourteen component organisms were isolated from the culture, including representatives of the genera Methylobacterium, Variovorax, Enterobacter, Aureobacterium, and Bacillus. The mixed culture biodegraded metal-EDTA complexes slowly; the biodegradability was in the order Fe > Cu > Co > Ni > Cd. By incorporation of inorganic phosphate into the medium as a precipitant ligand, heavy metals were removed in parallel to EDTA degradation. The mixed culture also utilized a number of possible EDTA degradation intermediates as carbon sources.     

High-Rate Biodegradation of Phenol by Aerobically Grown Microbial Granules

This study demonstrates that aerobic granules can be developed to achieve high phenol loading rates in a sequencing batch reactor. The reactor was started at a loading rate of 1.5 kg?phenol?m?3?d?1 with phenol-enriched activated sludge as inoculum. Granules first appeared on Day 9 after startup and quickly grew to become the dominant biomass in the reactor. The phenol loading was then adjusted stepwise to a final value of 2.5 kg?phenol?m?3?d?1. At this high loading, phenol was completely degraded and high biomass concentration was maintained in the reactor. The biomass continued to possess a good settling ability, with a sludge volume index of 60.5 mL?g?SS?1 (SS stands for suspended solids). Granules remained stable, without significant deterioration in granule structure and physiology, even at the maximum phenol loading rate tested. The applied selection pressure enabled the micro-organisms to aggregate into granules, and the compact structure of the aerobic granules served both to retain biomass and protect the microbial cells against the phenol toxicity. High specific phenol degradation rates exceeding 1 g?phenol?g?VSS?1?d?1 (VSS stands for volatile suspended solids) were sustained up to phenol concentrations of 500 mg?l?1, and significant rates continued to be achieved up to a phenol concentration of 1,900 mg?L?1. The phenol-degrading aerobic granules can be exploited to design compact high-rate aerobic granulation systems for the treatment of industrial wastewaters containing high concentrations of phenol and other inhibitory chemicals.     

蜂窝状微生物膜降解氨氮

实验利用新型悬浮载体对氨氮降解进行了研究.在悬浮载体上形成了蜂窝状的微生物薄膜结构,增加了微生物附着的比表面积,薄膜的形成有利于氧气的扩散和基质的转移,为硝化菌提供了有利的生存环境.实验在pH值为7.8~8.2,温度为24~29℃的条件下,当进水的氨氮质量浓度为40~78mg·L^-1时,经过3h的反应周期后,氨氮质量浓度下降到2mg·L^-1以下,COD从300mg·L^-1降低到50mg·L^-1以下;在反应周期为4h时,氨氮质量浓度从80~130mg·L^-1下降到3.5mg·L^-1以下,COD从350mg·L^-1降低到46mg·L^-1以下.结果表明,该悬浮载体上形成的生物膜结构有利于氨氮降解,反应器内实现了较好的COD和氨氮去除.     

Biodegradation of Nitroaromatics and RDX by Isolated Rhodococcus Opacus

Identification of bacteria that can utilize a wide range of nitroaromatic compounds will allow development of more effective biological treatment methods in industrial wastewater treatment processes and environmental remediation efforts. A new strain of Rhodococcus opacus capable of mineralizing or transforming nitroaromatic and nitramine compounds of importance was isolated. Specifically, the bacterium were found to utilize 2,4,6-trinitrophenol (TNP) as a sole carbon and nitrogen source and have a yield coefficient of 0.16 g cells-N/g TNP-N. The Edwards model was found to provide the best fit to the data and the estimated inhibited growth parameters μmax, KS, and KI were 0.58?h?1, 25, and 112?mg/L, respectively. It was found that the TNP-degraders could degrade 2,4-dinitrophenol as the sole carbon and nitrogen source and utilize 1,3,5-trinitrobenzene as the sole nitrogen source. Additionally, the results show that the isolates are able to cometabolize 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), 4-nitrophenol (4-NP), and 2,4- and 2,6-dinitrotoluene (2,4 and 2,6-DNT) to some extent when TNP is also present.     

Pollution of the agricultural lands of Bashkortostan by the herbicide 2,4-D and dioxins]

Market forces present the nursing profession with an urgency to prepare gerontological nurses to assume significant roles in the managed care industry. An understanding of the current managed care environment underscores the need for training. Nurses require a "managed care" skill-set encompassing a firm grasp of the organization, financing, delivery, and policy implications of managed care as well as advanced practice clinical skills and a sound business orientation. The importance of the consumer as a significant player in managed care is highlighted.