Transformation of p-nitrochlorobenzene by Escherichia coli

Microorganisms that have not been adapted to p-nitrochlorobenzene (p-NCB) are capable of transforming this compound. Washed cell of Escherichia coli, the resting culture and the homogenate of disintegrated cells transform p-NCB into p-chloroaniline (p-CA). The growing culture of E. coli (Eh = -210 mV) reduces the nitro group of p-NCB. If E. coli cells are separated from the cultural broth under strictly anaerobic conditions, the redox potential rises abruptly (Eh = -110 mV); the filtrate does not transform p-NCB into p-Ca. The rate at which E. coli reduces the nitro group of p-NCB depends on the redox potential of the medium. It is likely that any microorganism is capable of reducing p-NCB at a low value of the redox potential.     

Effect of various sources of organic carbon and high nitrite and nitrate concentrations on the selection of denitrifying bacteria. II. Continuous cultures in packed bed reactors

The effect of different organic compounds, nitrites and nitrates at the concentration of 1,000 mg N/l on the quantitative and strain-specific selection of denitrifying bacteria was determined in anaerobic packed bed reactors. Both the source of carbon and nitrogen form influenced strain specificity and the frequency of occurrence of denitrifying bacteria. The frequency of denitrifying bacteria within packed bed reactor ranged in different media from 11% (glucose and nitrates) to 100% (methanol and ethanol with nitrates). A single species selection was observed in the presence of nitrites within packed bed reactor: Pseudomonas aeruginosa in medium with acetate. Pseudomonas stutzeri in medium with ethanol, Pseudomonas mendocina in medium with methanol and Pseudomonas fluorescens in medium with glucose. When nitrates were present in packed bed reactor, the dominating bacteria were: P. stutzeri in medium with acetate, P. fluorescens in medium with ethanol, Paracoccus denitrificans in medium with methanol and Alcaligenes faecalis in medium with glucose.     

Enzymatic nitration of phytophenolics: evidence for peroxynitrite-independent nitration of plant secondary metabolites

Peroxynitrite (ONOO(-)), a reactive nitrogen species, is capable of nitrating tyrosine residue of proteins. Here we show in vitro evidence that plant phenolic compounds can also be nitrated by an ONOO(-)-independent mechanism. In the presence of NaNO(2), H(2)O(2), and horseradish peroxidase (HRP), monophenolic p-coumaric acid (p-CA, 4-hydroxycinnamic acid) was nitrated to form 4-hydroxy-3-nitrocinnamic acid. The reaction was completely inhibited by KCN, an inhibitor for HRP. The antioxidant ascorbate suppressed p-CA nitration and its suppression time depended strongly on ascorbate concentration. We conclude that nitrogen dioxide radical (NO(2)(radical)), but not ONOO(-), produced by a guaiacol peroxidase is the intermediate for phytophenolic nitration.     

Effect of nitrates on biotransformation of phosphogypsum and phenol uptake in cultures of autochthonous sludge microflora from petroleum refining wastewaters

The effect of nitrates on the biotransformation of phosphogypsum at 30 degrees C in stationary cultures of anaerobic, heterogeneous microflora growing in medium with phenol (250-1,000 mg/L) as sole carbon source was studied. The microorganisms used in this study were isolated from sludge in biological petroleum-refining wastewater treatment plant. Phosphogypsum (a waste product in the chemical industry that contains approximately 95% CaSO4) was added in amount of 5 g/L, the source of nitrates was KNO3 in concentration equivalent to that of phenol (250-1,000 mg N-NO3/L). The presence of nitrates in heterogeneous cultures has an inhibitory effect on the process of phosphogypsum biotransformation and stimulates the uptake of phenol. We have found that in cultures in medium containing phenol, phosphogypsum and nitrates at least three physiological groups of microorganisms were present. These were phenol-biodegrading microorganisms not requiring an external electron acceptor, sulfate-reducing bacteria biodegrading phenol or intermediate products of its breakdown and denitrifying bacteria not utilising phenol as a carbon source. On solid medium these bacteria together formed heterogeneous single colonies. In spite of repeated attempts we were unable to isolate pure strains and the only result of these measures was loss of denitrification ability in medium with phenol.     

Changes in the Nitrocellulose Molecule Induced by Sulfate-Reducing Bacteria Desulfovibrio desulfuricans 1388. The Enzymes Participating in This Process

The appearance of unsubstituted glucopyranose residues in nitrocellulose (NC) induced by Desulfovibrio desulfuricans was established by (13)C-NMR spectroscopy. After contact with bacterial cells, the degree of substitution by nitro groups in NC decreased from 2.59 to 2.40. The bacteria possess intra- and extracellular nitroesterase activities, which are responsible for denitration of the polymer. The presence of NC in the growth medium influences the extracellular nitroesterase activity. It is shown that inhibition of enzymatic activity in the presence of NC is caused by appearance of nitrates in the culture medium. Nitrate and nitrite reductases of dissimilatory type reduce nitrates. The data suggest consideration of bacteria belonging to the Desulfovibrio genus as the initial agent in utilization of an unnatural polymer--nitrocellulose--in a microbial consortium.     

血清和胸水中CA125在结核性和癌性胸水中的表达及临床意义

目的:探讨血清和胸水中CA125在结核性和癌性胸水中的表达及鉴别诊断意义。方法:抽选我院确诊的结核性胸水病人85例(结核组)和癌性胸水病人71例(癌症组),检测两组患者血清和胸水中CA125表达,并以胸水/血清中CA125比值10(p-CA125/s-CA12510)为临界值,观察其对癌性胸水的鉴别特异度、灵敏度及准确性。结果:癌症组胸水中CA125表达及p-CA125/s-CA125比值均显著高于结核组(P0.05);但血清中两组CA125表达比较差异无显著性(P0.05);两组胸水中,以35U/ml为临界值,两组患者阳性率92.9%(79/85)、100%(71/71)比较差异无显著性(X2=7.0718,P=0.0078)。癌症组中p-CA125/sCA125比值10的比率(84.5%VS 17.6%)明显高于结核组(X2=66.6244,P=0.0000);并以其为诊断癌性胸水的临界值,鉴别诊断特异度、灵敏度及准确性分别为82.3%、84.5%、83.3%。结论:血清和胸水中CA125表达对于鉴别结核性或者是癌性胸水的临床意义不大,但是p-CA125/s-CA125比值对于鉴别结核性和癌性胸水具有一定临床价值。     

La diamine oxydase dans les jeunes plantes de Glycine max

Diamine oxidase activity against putrescine and agmatine is investigated in young decotylized Glycine max plants growing, in the light, under sterile conditions on a liquid medium in the presence of ammonium chloride or nitrates. Optimal conditions for the enzyme activity are determined. Both amines are oxidised more slowly in plants cultivated on ammonium chloride than in plants grown on nitrates.     

Ultrastructure of bacteroid-containing tissue of Pisum sativum L. peas having various regulatory mechanisms of nodulation

The infected root nodule cells of Pisum sativum cvs. Torsdag, Rondo and its supernodulating mutant nod3 have been investigated by transmission electron microscopy and morphometrically. Torsdag and nod3 developed effective nodules, when grown with or without nitrates in the growth medium. The nodules developed by Rondo were ineffective in the presence of nitrates, and otherwise effective. An obvious similarity in the fine structure of bacteroid tissue of root nodules has been observed in Torgsdag (Nod5) and the supernodulating mutant nod3, both forms being nitrate-tolerant, but nodulation being controlled by different genetic systems. The statistical processing results showed significant differences in the respective morphometric parameters of nodule cells between the plants grown according to either scheme: with and without nitrates. Combined nitrogen is likely to affect the ratio of symbionts in the infected nodule cells of cultivars with nitrate-tolerant nodulation.     

Stimulation of nitrate reductase activity of the salt-tolerant yeast Rhodotorula glutinis by tungsten in the presence of molybdenum

Tungsten in the presence of molybdenum stimulates nitrate reductase activity and growth of the salt-tolerant yeast Rhodotorula glutinis on medium with nitrates. Tungsten is not incorporated in proteins possessing nitrate reductase activity. A significant increase in molybdenum cofactor in cells grown on medium with equimolar amounts of molybdenum and tungsten may relate to the stimulatory action of tungsten.     

Biotransformation of phosphogypsum in media containing different forms of nitrogen

Studies on the biotransformation of phosphogypsum (a waste product formed in the course of the production of phosphorous fertilizers) with the use of sulfate reducing bacteria (SRB) demonstrated that it is a good source of sulfates and biogenic elements for these bacteria, though the addition of organic carbon and nitrogen is necessary. The aim of this study was to investigate the form of nitrogen and C:N ratio in the medium on the growth of SRB community in cultures containing phosphogypsum. Batch community cultures of sulfate reducing bacteria were maintained in medium with phosphogypsum (5.0 g/l), different concentrations of sodium lactate (1.6 - 9.4 g/l) and different forms (NH4CI, CO(NH2)2, KNO3) and concentrations (0 - 250 mg/l) of nitrogen. The growth of SRB was studied in the C:N ratio of from 2:1 to 300:1. It was found that: 1 - the best source of nitrogen for SRB is urea, followed by ammonium, the worst were nitrates; 2 - the bacteria were also able to grow in medium without nitrogen but their activity was then by approximately 15% lower than in optimal growth conditions; 3 - in medium with KNO3 inhibition of sulfate reduction by approx. 50% was observed; 4 - the highest reduction of nitrates (removal of nitrate) in media with phosphogypsum and nitrates was at limiting concentrations of sodium lactate. This is probably caused by the selection under these conditions (low concentration of hydrogen sulfide) of denitrifying bacteria or sulfate reducing bacteria capable of using nitrates as an electron acceptor.     

Characterization of two new aromatic amino acid lyases from actinomycetes for highly efficient production of p-coumaric acid

Bioprocess and Biosystems Engineering - p-Coumaric acid (p-CA) is a bioactive natural product and an important industrial material for pharmaceuticals and nutraceuticals. It can be synthesized from...     

Inorganic phosphate stimulates the toxic effects of Tl+ in rat liver mitochondria

We studied action of inorganic phosphate (P(i)) on toxic effects of Tl+ in isolated rat liver mitochondria. This is a convenient model to study the toxicity of heavy metals. P(i) markedly retarded contraction of energized mitochondria swollen in the TlNO3 medium and even stronger stimulated swelling and state 4 of succinate-energized mitochondria in the TlNO3 medium. A valinomycin-induced decrease of K+-diffusion potential was also accelerated by Tl+ in the presence of P(i). The mitochondrial permeability transition pore in the medium containing Ca2+, TlNO3, and nitrates of univalent cations was distinctly stimulated by P(i). However, P(i) did not affect both the Tl+-stimulated swelling of nonenergized mitochondria in the TlNO3 medium and swelling of energized mitochondria in the Tl acetate medium. Respiration stimulated by 2,4-dinitrophenol and monoamine oxidase activity of energized mitochondria were not affected by Tl+ regardless of the presence of P(i). We suggested that stimulation by P(i) of toxic action of Tl+ in mitochondria and cells could be due to even greater enhancement of uncoupling of mitochondria as shown by an additional increase of swelling and state 4, and in the greater probability of opening of MPTP in the presence of P(i) and Ca2+.     

Devenir de la putrescine-1,4-14C chez Glycine max

Fate of Putrescine-1,4-¹⁴C in Glycine max Putrescine-1,4-¹⁴C was supplied to young decotylized Glycine max (L.) Merr. cv. Chippewa plants growing under aseptic conditions on a liquid medium with nitrogen supplied either as ammonium chloride or nitrates. Whatever the source of nitrogen the diamine was quickly transformed to γ-aminobutyric acid, succinic acid and malic acid; only a very minor part was utilized for the synthesis of polyamines. In the presence of ammonium chloride the putrescine catabolism may be slower than in the presence of nitrates. The results are explained by a weak isotopic dilution or by a diamine oxidase activity lower in “ammonium” plants than in “nitrate” plants; the two causes might co-exist. The possibility of a diamine compartmentation has to be considered.     

Kinetics of uptake of phosphates and nitrates by marine multicellular algae <Emphasis Type="Italic">Gelidium latifolium</Emphasis> (Grev.) Born. et Thur.

We studied nonstationary kinetics of the uptake of phosphates and nitrates by the red marine algae Gelidium latifolium (Grev.) Born et Thur. and calculated constants of the Michaelis-Menten equation for these elements. In the area of 0–3 μM, the kinetics of phosphate consumption had the following coefficients: maximum rate of uptake 0.8 μmol/(g h), constant of half-saturation 1.745 μM. For nitrate nitrogen at 0–30 μM, an adaptive strategy of uptake kinetics was noted with change of the equation parameters with time: after 1 h, the maximum rate of uptake was 5.1 μmol/(g h) and constant of half-saturation 19 μM, while within 2 h, the maximum rate of uptake significantly increased. This could be related to the synthesis of nitrate reductase. Coupled with the uptake of nitrates, nonstationary kinetics of the release of nitrates in the surrounding medium had a one-peak pattern: the maximum concentration of nitrites in the medium and the time of its achievement increased with the initial concentration of nitrates. The maximum concentration of nitrites was 6 to 14% of the initial concentration in the medium.     

Denitrification of high concentrations of nitrites and nitrates in synthetic medium with different sources of organic carbon. III. Methanol

The denitrification of nitrites and nitrates (1000 mg N/l) in medium containing methanol as a source of organic carbon was studied. Continuous cultures of mixed population of autochtonic microflora from bottom sludge of nitrogenous wastewater reservoir were set up in a chemostat-type column and packed bed reactor. The efficiency of denitrification of nitrates in packed bed reactor was 506.7 mg N/l/h whereas denitrification of nitrites was from 8.7 to 16.0 mg N/l/h depending on the granulation of the filing material. In the latter case 83% nitrogen was removed from the medium. One of the factors causing low efficiency of denitrification of nitrites is excessive alkalization of the medium in the bed. The use of a three-step bed with adjusted pH resulted in complete denitrification of nitrites with efficiency 60 mg N/l/h. The bacteria inside the bed were dominated by Paracoccus denitrificans and by Pseudomonas aeruginosa when nitrates were present. The sensitivity of P. denitrificans to high concentrations of nitrites seems to be the second factor contributing to low efficiency of denitrification with methanol as organic substrate.     

Seasonal variation of nitrogenous compounds in the xylem sap of Citrus

Samples of tracheal sap of Citrus sinensis (L.) Osbeck cv. Washington Navel were taken from field trees throughout the year and the nitrogen composition of the sap was determined. The nitrogenous fraction of the sap was composed mainly of free amino acids (92–97% of total nitrogen) and nitrates throughout the year. Proline was the most abundant amino acid during almost the entire cycle, and its concentration was especially high during the autumn and winter period. Nevertheless, a significant part (40–60%) of the total organic nitrogen was transported as arginine. Total nitrogen as well as amino acids and nitrates were maximal at spring flush. At spring flush and summer flush there was also a diversification of α-amino nitrogen among different amino acids. During the spring flush, nitrates, asparagine and γ-aminobutyric acid in the xylem sap seemed to have a radicular origin, whereas glutamic acid and arginine were released from the surrounding parenchyma. The results suggest a metabolic transformation in the wood parenchyma of nitrogenous compounds coming from the roots (including reduction of nitrates) and a turnover of different nitrogen metabolites between the xylem and surrounding cells.     

Kinetic and analytical study of the photo-induced degradation of monuron by nitrates and nitrites under irradiation or in the dark

The photo-induced transformation of monuron (3-(4-chlorophenyl)-1,1 dimethylurea) was investigated in an aqueous solution containing nitrates and nitrites at 310 nm and 365 nm, respectively. In both NO(3)(-) and NO(2)(-) conditions, the degradation of monuron followed pseudo-first order kinetics. The intermediate products were identified by GC-MS, and the nitration, hydroxylation and coupling reactions were determined. In addition, the oxidation of the N-terminus group, the substitution of chlorine by ˙OH and the nitration by ˙NO(2) radical onto the phenyl ring were observed. The photo-induced transformation of monuron was studied under variable conditions of pH, inducer concentration, substrate concentration, humic acids, oxygen content and salts used as hydroxyl radical scavengers. The photodegradation rates were strongly influenced by all the above parameters. The degradation of monuron was also studied in the dark and in the presence of NO(2)(-) as well as in an aqueous solution with the addition of hydrogen peroxide.     

Fertilisation de communautés phytoplanctoniques. ii. cas d'un milieu eutrophe: upwelling des côtes du sahara espagnol

Experiments with nutrient enrichment of phytoplankton communities have been carried out on surface waters from the upwelling area off Cap Blanc — Cap Corveiro (Spanish Sahara).None of the control flasks showed phytoplankton development despite the large quantities of nutrient available: this may be due to the presence of an inhibitor in the upwelling waters. On the other hand, most of the enrichments stimulated the autotrophic production. On average, the best growth rates were obtained when a full medium minus Fe-EDTA was added; marked phytoplankton development also took place when a medium without vitamins, or silicates, or phosphates, was added. Lack of metallic compounds (other than iron) and nitrates limit the algal growth.The maximum amounts of chlorophyll a (25–30 mg/m³) are close to the maxima usually observed in this area. The productivity rate (biomass produced/nutrients used) is very high.     

A comparison of growth rate of algae as influenced by variation in nitrogen nutrition inChlorella pyrenoidosa andScenedesmus obliquus

Algae were cultivated in nutrient solutions containing nitrates or ammonium salts as the nitrogen source. We measured the culture density in the case of autotrophic and mixotrophic cultivation at different pH values, in the presence of nitrate also at different concentrations and in the absence of molybdenum. The dry weight and amount of nitrogen in the cells under these conditions were determined. According to results obtained we conclude thatChlorella, in contrast toScenedesmus, prefers ammonia as the nitrogen source in the first growth period, later both prefer nitrogen from nitrates. Nitrogen from ammonium salts has a positive effect only during short-time cultivation. If glucose was used as a mixotrophic energy source (or perhaps H-donor), the unsuitability of ammonia as a nitrogen source was more marked. We suppose that the lower growth intensity of older cultures (i.e., after seven days) in ammonia medium is the result of the use of endogenous energy sources. Both algae have adaptive systems making it possible to use nitrate nitrogen even in the absence of molybdate.     

Enzyme activity of the formate hydrogenlyase complex in Citrobacter freundii

Citrobacter freundii 62 can grow in the absence of oxygen in media containing glucose, peptone, fumarate or malate. When the medium contained fumarate or malate, the culture could grow under anaerobic conditions only in the presence of molecular hydrogen, formate or nitrate. The highest activity of formatehydrogenlyase and hydrogenase was found when C. freundii grew in a medium with glucose and formate. The activity was lower in media with other organic substrates, particularly, in the absence of formate or H2. The activity of hydrogenase was very low in cells grown under aerobic conditions or in the presence of nitrates while the activity of formatehydrogenlyase was not found at all for all practical purposes. The activity of formate dehydrogenase assessed in the presence of methylene blue was rather high irrespective of the conditions under which the culture was grown. However, when the activity of formate dehydrogenase was determined in the presence of benzyl viologen, it was high only in cells grown in the medium with glucose and formate.