The effect of 2, 4-dinitrophenol on the growth of Bordetella pertussis in chick tracheal organ culture.

Among various metabolic inhibitors tested, only 2, 4-dinitrophenol inhibited the growth of Bordetella pertussis in chick tracheal organ culture at concentrations nontoxic both for bacterial organisms and for ciliary motility of the tracheal fragments. Although this effect of 2, 4-dinitrophenol was reversible in its early stage, longer treatment with this inhibitor resulted in an irreversible inhibition of bacterial growth due to secondary damage of the tracheal fragments. From these observations, it was postulated that the energy required for bacterial growth might be derived from cellular metabolism sensitive to inhibition with 2, 4-dinitrophenol.     

Effect of xenobiotics on inorganic nitrogen assimilation by the phototrophic bacteriumRhodobacter capsulatus E1F1

In the presence of nitroaromatic and haloaromatic derivatives,Rhodobacter capsulatus E1F1 growth was affected in different degrees depending on the nitrogen source used. Phototrophic growth on glutamate or ammonium was not inhibited by 2,4-dinitrophenol (2,4-DNP), 4-nitrophenol (4-NP), 2-amino-4-nitrophenol (2,4-ANP), 4-aminophenol (4-AP), or 4-chlorophenol (4-CIP), whereas 2,4-dinitrophenol and 4-chlorophenol partially inhibited bacterial growth in nitrate, nitrite, and dinitrogen. On the other hand, although photosynthetic nitrate uptake was significantly inhibited by 2,4-dinitrophenol, 4-chlorophenol inhibited it to a lesser extent. Nitrogen fixation was severely inactivated in vivo by 2,4-dinitrophenol, but nitrate reductase activity was activated in vivo by 2,4-dinitrophenol, 4-nitrophenol, and 4-chlorophenol. Similar effects were found in cells growing with nitrate and 2,4-dinitrophenol under dark and aerobiosis conditions. None of the enzymatic activities related to inorganic nitrogen assimilation were affected by xenobiotics in vitro.     

Effects of DNP on the cell surface properties of marine bacteria and its implication for adhesion to surfaces

Abstract

The effect of 2, 4-dinitrophenol (DNP) on the extracelluar polysaccharides (EPS), cell surface charge, and the hydrophobicity of six marine bacterial cultures was studied, and its influence on attachment of these bacteria to glass and polystyrene was evaluated. DNP treatment did not influence cell surface charge and EPS production, but had a significant effect on hydrophobicity of both hydrophilic (p = 0.05) and hydrophobic (p = 0.01) cultures. Significant reduction in the attachment of all the six cultures to glass (p = 0.02) and polystyrene (p = 0.03) was observed after DNP treatment. Moreover, hydrophobicity but not the cell surface charge or EPS production influenced bacterial cell attachment to glass and polystyrene. From this study, it was evident that DNP treatment influenced bacterial cell surface hydrophobicity, which in turn, reduced bacterial adhesion to surfaces.     

Extranuclear mutant ofSchizophyllum commune

A mutant of the hymenomyceteSchizophyllum commune was isolated which, owing to an extranuclear mutation, did not utilize acetate as the sole carbon source for growth. The growth of the mutant on glucose minimal medium was completely inhibited by sodium azide but was resistant to the effect of 2,4-dinitrophenol or oligomycin. Its endogenous respiration was cyanide-sensitive and was stimulated by 2,4-dinitrophenol to a considerably smaller degree than that of the wild-type strain. The experimental results obtained with this mutant suggest a defect in aerobic phosphorylation.     

Cloning of the immunity repressor determinant of bacteriophage P2 in the pBR322 plasmid

Summary Through in vitro recombination of DNA restriction fragments, we have constructed a plasmid, which expresses in vivo the immunity repressor gene (C) of bacteriophage P2. A bacterial strain carrying such a plasmid showed a high level of P2 specific immunity. It was lysogenized normally by an infecting P2. but the frequency of spontaneous phage production was reduced about 10⁴ fold as compared to a normal P2 lysogen. Satellite phage P4, known to derepress P2 lysogens, was unable to derepress the plasmid-carrying lysogenic strain so to allow growth of coinfecting P2. Phage P4 multiplied on the plasmid-carrying. P2-lysogenic strain, but due to a prolonged latent period failed to form plaques on this strain.     

Biodegradation of the pesticide 4,6-dinitro-ortho-cresol by microorganisms in batch cultures and in fixed-bed column reactors

A mixed culture of microorganisms able to utilize 4,6-dinitro-ortho-cresol (DNOC) as the sole source of carbon, nitrogen and energy was isolated from soil contaminated with pesticides and from activated sludge. DNOC was decomposed aerobically in batch cultures as well as in fixed-bed column reactors. Between 65% and 84% of the substrate nitrogen was released as nitrate into the medium, and 61% of the carbon from uniformly ¹⁴C-labelled DNOC was recovered as ¹⁴CO₂. The mixed microbial culture also decomposed 4-nitrophenol and 2,4-dinitrophenol but not 2,3-dinitrophenol, 2,6-dinitrophenol, 2,4-dinitrotoluene, 2,4-dinitrobenzoic acid or 2-sec-butyl-4,6-dinitrophenol (Dinoseb). Maximal degradation rates for DNOC by the bacterial biofilm immobilized on glass beads in fixed-bed column reactors were 30 mmol day⁻¹ (l reactor volume)⁻¹, leaving an effluent concentration of less than 5 μg l⁻¹ DNOC in the outflowing medium. The apparent K _s value of the immobilized mixed culture for DNOC was 17 μM. Degradation was inhibited at DNOC concentrations above 30 μM and it ceased at 340 μM, possibly because of the uncoupling action of the nitroaromatic compound on the cellular energy-transducing mechanism. Received: 27 March 1997 / Received revision: 5 June 1997 / Accepted: 7 June 1997     

Effect of 2-deoxy-D-glucose on the Respiration of Tropical Anthracnose Fungi

This study begins an investigation of the chemical activities of one of the most destructive groups of spoilage organisms of tropical foods, the anthracnose fungi. The present paper treats of an introductory investigation on carbohydrate metabolism. Two fungi isolated from rotted banana tissue, Gloeosporium musarum and Colletotrichum gloeosporioides, were grown in the presence of 2-deoxy-D-glucose, a metabolic blocking agent, in shake culture. The mycelia produced were studied in the Warburg respirometer in the presence of glucose, 2-deoxyglucose, and 2,4-dinitrophenol. Gloeosporium musarum was found to be incapable of growth in the presence of 2-deoxyglucose as the sole carbon source, but did grow when glucose was added. Colletotrichum gloeosporioides grew normally, but at a slower rate on 2-deoxyglucose than on glucose. Glucose grown G. musarum and C. gloeosporioides both exhibited respiratory inhibition in the presence of 2-deoxyglucose, whereas 2-deoxyglucose adapted C. gloeosporioides did not. The uncoupling agent 2, 4-dinitrophenol induced respiratory stimulation except in the presence of 2-deoxyglucose in glucose grown C. gloeosporioides where it caused a drop in oxygen uptake.     

The regulation of growth hormone secretion from the isolated rat anterior pituitary in vitro. The role of adenosine 3′:5′-cyclic monophosphate

1. The release of growth hormone from isolated fragments of rat anterior pituitary tissue incubated in vitro was studied by employing a double-antibody radioimmunoassay. 2. In the absence of added stimuli, two phases of hormone release could be distinguished, an early phase of 2h duration and a subsequent late phase. In the early phase, hormone release was rapid but could be significantly decreased by calcium depletion and by 2,4-dinitrophenol whereas the rate of release in the late phase was uninfluenced by these incubation conditions. These results have been interpreted as indicating the existence of a secretory component in the early phase of release. 3. In subsequent experiments, the effects of various agents on the rate of hormone output during the late phase of incubation were investigated. Hormone release was increased by theophylline and by dibutyryl cyclic AMP (N(6)-2'-O-dibutyryl-adenosine 3':5'-cyclic monophosphate), the response to both of these agents being related to the concentration of the stimulant employed. 4. The stimulation of growth hormone output by theophylline was significantly decreased by calcium deprivation and by 2,4-dinitrophenol. The response to dibutyryl cyclic AMP was diminished by 2,4-dinitrophenol, iodoacetate and 2-deoxyglucose but not by malonate or colchicine. 5. Arginine, beta-hydroxybutyrate, albumin-bound palmitate and variation in the glucose concentration of the incubation medium over a wide range were without any statistically significant effect on the rate of hormone release from either control pituitary fragments or those subject to secretory stimulation by dibutyryl cyclic AMP. 6. It is suggested that the regulation of growth hormone secretion is mediated by cyclic AMP (adenosine 3':5'-cyclic monophosphate). The secretion observed in response to cyclic AMP requires the presence of ionized calcium and a source of metabolic energy but is independent of pituitary protein synthesis de novo. The integrity of the glycolytic pathway of glucose metabolism appears to be essential for cyclic AMP-stimulated growth hormone secretion to occur.     

Photoinactivation of the detoxifying enzyme nitrophenol reductase from Rhodobacter capsulatus

The phototrophic bacterium Rhodobacter capsulatus E1F1 detoxifies 2,4-dinitrophenol by inducing an NAD(P)H-dependent iron flavoprotein that reduces this compound to the less toxic end product 2-amino-4-nitrophenol. This nitrophenol reductase was stable in crude extracts containing carotenes, but it became rapidly inactivated when purified protein was exposed to intense white light or moderate blue light intensities, especially in the presence of exogenous flavins. Red light irradiation had no effect on nitrophenol reductase activity. Photoinactivation of the enzyme was irreversible and increased under anoxic conditions. This photoinactivation was prevented by reductants such as NAD(P)H and EDTA and by the excited flavin quencher iodide. Addition of superoxide dismutase, catalase, tryptophan or histidine did not affect photoinactivation of nitrophenol reductase, thus excluding these reactive dioxygen species as the inactivating agent. Substantial protection by 2,4-dinitrophenol also took place when the enzyme was irradiated at a wavelength coinciding with one of the absorption peaks of this compound (365nm). These results suggest that the lability of nitrophenol reductase was due to the absorption of blue light by the flavin prosthetic group, thus producing an excited flavin that might irreversibly oxidize some functional group(s) necessary for enzyme catalysis. Nitrophenol reductase may be preserved in vivo from blue light photoinactivation by the high content of carotenes and excess of reducing equivalents in phototrophic growing cells.Abbreviations 2,4-DNP 2,4-dinitrophenol - ANP 2-amino-4-nitrophenol - EDTA ethylenediamine tetraacetic acid - MES 2-(N-Morpholino) ethanesulfonic acid - NPR nitrophenol reductase     

Chlorophenol and nitrophenol metabolism by Sphingomonas sp UG30

Sphingomonas sp UG30 is a pentachlorophenol (PCP)-degrading bacterial strain capable of degrading several nitrophenolic compounds, including p-nitrophenol (PNP), 2,4-dinitrophenol (2,4-DNP), p-nitrocatechol and 4,6-dinitro-o-cresol (DNOC). The ability to degrade both chlorophenolic and nitrophenolic compounds is probably not restricted to UG30, but may also be possessed by other pentachlorophenol-degrading Sphingomonas spp. The interesting question arises as to whether there is any point of convergence between the initial pathways of PCP and nitrophenol degradation in these microorganisms. There is some experimental evidence that PCP-4-monooxygenase is involved in metabolism of both p-nitrophenol and 2,4-dinitrophenol. Further studies are needed to confirm this and to examine the role(s) of other PCP-degrading enzymes in nitrophenol metabolism by this microorganism. In this paper, we review some of the taxonomic, biochemical, physiological and ecological properties of Sphingomonas sp UG30 with respect to biodegradation of PCP and nitrophenolic compounds. Received 19 April 1999/ Accepted in revised form 21 August 1999     

Metabolism of nitrophenols by bacteria isolated from parathion-amended flooded soil

Two bacterial isolates from parathion-amended flooded soil, Pseudomonas sp. and Bacillus sp., were examined for their ability to decompose nitrophenols. Uniformly labelled ¹⁴C-p-nitrophenol was metabolized by both bacteria, ¹⁴CO₂ and nitrite being end products. A substantial portion (23% for Pseudomonas sp. and 80% for Bacillus sp.) of radioactivity applied as p-nitrophenol was accounted for as ¹⁴CO₂ at the end of a 72-h period; 8 to 16% remained in the water phase after solvent extraction. Pseudomonas sp. produced nitrite also from 2,4-dinitrophenol, but only after a lag, and not from o- and m-nitrophenols. Interestingly, m-nitrophenol, known for its resistance to biodegradation because of meta substitution, was decomposed by Bacillus sp., resulting in the formation of nitrite and phenol; o-nitrophenol and 2,4-dinitrophenol resisted degradation by this bacterium.     

Nutrient enrichment promotes survival and dispersal of drifting fragments in an invasive tropical macroalga

The effect of nutrient availability on growth, survival, and photosynthetic performance of drifting fragments of the invasive red alga Hypnea musciformis was studied in Maui (Hawaii), where this species smothers native reef communities and forms localized blooms. H. musciformis does not sexually reproduce in Hawaii and drifting fragments represent the only pathway by which H. musciformis can disperse and invade new areas. Growth rates decreased with age and approached zero when fragments aged 32 days. Increased nutrient availability did not result in increased relative growth rates during this period. In contrast to growth, photosynthetic performance remained unaffected through time and showed no clear relationship with nutrient availability. Increased nutrient availability increased fragment survival and fragments survived for >2 months in the high nutrient treatment (3.0 μmolPO₄ + 30.0 μmolNH₄). This indicates that increased nutrient availability increases the dispersal potential of H. musciformis. Low growth rates of drifting Hypnea fragments increased recruitment success since attachment success of this epiphytic species decreased with increasing fragment size. H. musciformis thus uses resources for survival and maintenance rather than growth, resulting in long competency periods and optimal recruitment, which likely contribute to its success as an invader of Hawaiian reef communities.     

Antiviral activity of Lactobacillus brevis towards herpes simplex virus type 2: role of cell wall associated components

The aim of this research was to study the mechanisms of Lactobacillus brevis antiviral activity towards HSV-2 and to identify the bacterial components responsible for the inhibiting effect. Bacterial extract and cell walls were prepared by lysozyme digestion of L. brevis cells untreated or treated with LiCl to remove S-layer proteins. Bacterial extract and cell wall fragments showed a dose dependent inhibitory effect on HSV-2 multiplication. In order to characterize the inhibitory activity of L. brevis, the bacterial extract was subjected to different physical and chemical treatments. The inhibitory activity was resistant to high temperature and proteases digestion and appeared to be associated with compounds with a molecular weight higher than 10 kDa. DNA, RNA and lipids isolated from bacterial cells were devoid of inhibitory effect. The antiviral activity of both bacterial extract and cell wall fragments obtained from L. brevis cells after the S-layer removal was significantly reduced compared to untreated cells suggesting that the inhibitory activity is likely due to a heat-resistant non-protein cell surface bacterial component.     

Catabolism of 2,6-dinitrophenol by Alcaligenes eutrophus JMP 134 and JMP 222

Both Alcaligenes eutrophus JMP 134 and its plasmid-free derivative Alcaligenes eutrophus JMP 222 utilize 2,6-dinitrophenol as sole source of carbon, energy, and nitrogen. In the presence of ammonia resting cells of these strains release two mol of nitrite per mol of 2,6-dinitrophenol. Alcaligenes eutrophus JMP 222-1D, a mutant of strain JMP 222 obtained by transposon (Tn5) mutagenesis, is able to use 2,6-dinitrophenol as nitrogen source but not as source of carbon and energy. Resting cells of this mutant liberate only one mol of nitrite per mol of 2,6-dinitrophenol. A single metabolite was detected by high-pressure liquid chromatography and identified as 2-hydroxy-5-nitropenta-2,4-dienoic acid from the mass spectrum, the ¹H-, and ¹³C-NMR spectra. Strain JMP 222-1S, a spontaneous mutant of strain JMP 222-1D, accumulates 4-nitropyrogallol which was identified as the initial metabolite of 2,6-dinitrophenol degradation.Non-standard abbreviations 2,4-D 2,4-dichlorophenoxyacetic acid - 2,6-DNP 2,6-dinitrophenol - HNMA 2-hydroxy-5-nitromuconic acid - HNPA 2-hydroxy-5-nitropenta-2,4-dienoic acid - NB nutrient broth - NMR nuclear magnetic resonance - NPG 4-nitropyrogallol - O.D. optical density - t_R retention time - UV/Vis ultraviolet/visible     

A whole-organ perfusion model of bordetella pertussis adherence to mouse tracheal epithelium

Summary A whole-organ perfusion system was used to culture tracheas from adult Swiss mice and test this system's adaptability for use in adherence assays for virulentBordetella pertussis. Culture medium and bacterial suspensions flowed readily through the tracheal lumen, ciliary activity was maintained throughout the culture period, and scanning electron microscopy revealed retention of normal surface morphology. The number of adherent colony-forming units (cfu) per trachea was determined for all threeBordetella species every 30 min over a 3.5-h incubation period and the resultant adherence patterns were reproducible. Adherent cfu were dependent on the concentration of microorganisms in the infecting inoculum.Bordetella pertussis did not demonstrate a preferential adherence to either the dorsal or ventral surface of the tracheal epithelium nor did it demonstrate a preference for adherence to the laryngeal or bronchial end of the trachea. Static growth conditions did alter the adherence pattern ofB. pertussis from that observed when the organism was grown with constant agitation. This work was presented in part at the 1984 annual meeting of the American Society for Microbiology, St. Louis, MO.     

Effects of the biocontrol agent Bacillus amyloliquefaciens SN16‐1 on the rhizosphere bacterial community and growth of tomato

Fusarium oxysporum is a common soil‐borne pathogen that causes serious economic losses in tomato crops worldwide. The purpose of this study was to evaluate the influence of the bio‐control agents Bacillus amyloliquefaciens SN16‐1 and Pseudomonas fluorescens SN15‐2 and the pathogen Fusarium oxysporum f.sp. lycopersici (FOL) inoculation on tomato rhizosphere bacterial communities and growth, as measured by terminal restriction fragment length polymorphism (T‐RFLP). Treatment with SN16‐1 and SN15‐2 had a transient influence on indigenous bacterial communities, withSN16‐1 showing great potential for controlling FOL. The corresponding genera of terminal restriction fragments (T‐RFs) that were significantly altered after 10 days were obtained using Ribosomal Database Project (RDP) database comparison. Genera that produce antibiotics and promote plant growth were activated by SN16‐1 and FOL treatments, indicating that SN16‐1 responds quickly to FOL invasion. Moreover, the bioremediation activity characteristic of certain genera and the levels of enzymes that degrade pathogen cell walls were decreased while bacterial nutrient cycling and plant growth promotion were enhanced with FOL treatment. In conclusion, we found that SN16‐1 possesses the capacity to control tomato wilt, acts synergistically with soil microbes and does not have a persistent effect on the rhizosphere bacterial communities of tomato.     

Discrimination between Atlantic and Pacific Subspecies of Northern Bluefin Tuna (Thunnus thynnus) by Magnetic-Capture Hybridization Using Bacterial Magnetic Particles

The previously developed magnetic-capture hybridization technique employing bacterial magnetic particles was applied to discriminate between Atlantic and Pacific subspecies of the northern bluefin tuna (Thunnus thynnus) using specific DNA sequences. Nucleotide sequences of a 925-bp fragment (ATCO) flanking the mitochondrial ATPase and cytochrome oxidase subunit III genes in these two subspecies were compared. Two regions having single-nucleotide and three-nucleotide differences between the subspecies were adopted to design DNA probes (NR1, 21-mer; NR2, 29-mer), and two internal primer sets were designed to amplify DNA fragments containing these regions. The DNA probes were immobilized on bacterial magnetic particles via streptavidin-biotin conjugation and subjected to magnetic-capture hybridization with the digoxigenin-labeled fragments amplified using the internal primers. The luminescence intensities of DNA on bacterial magnetic particles obtained by hybridization between the probes and the complementary fragments were higher than those obtained by hybridization with noncomplementary fragments. These data suggest that this system employing DNA on bacterial magnetic particles may be useful for discrimination of these two subspecies by recognizing a single-nucleotide difference. Received January 17, 2000; accepted January 28, 2000.     

Coral reef restoration in the Eastern Tropical Pacific: feasibility of the coral nursery approach

Due to the worldwide degradation of coral reefs, the active restoration of these ecosystems has received considerable attention in recent decades. This study investigated (1) the feasibility of using coral nurseries for restoration projects, (2) the minimum size required for a Pocillopora damicornis (Pocilloporidae) coral fragment to survive and grow in a nursery, and (3) the optimal transplant size of a fragment when transplanted to a degraded reef at Gorgona Island (Colombian Pacific). For this investigation, 230 fragments were transplanted directly to El Remanso reef, and another 150 fragments were maintained in in situ nurseries. Every 2 months, the length, weight, and survival of the fragments were recorded. After growing for 134 days in the nurseries, the 52 surviving fragments were transplanted to El Remanso reef, and after 5 months, the same variables were measured. Among the nursery‐reared fragments, the largest (4 to <8 cm) had the highest survival and growth rates, whereas among the directly transplanted fragments, the smallest fragments (<2 cm) had the highest survival and growth rates. However, the nursery‐reared fragments acquired greater structural complexity (arborescent morphology), and they were all alive 156 days after transplantation and presented a maximum linear growth rate of over 2 cm, which was higher than that of the directly transplanted fragments. Apparently, the arborescent morphology acquired during the nursery period provides advantages to the colonies that favor greater success when transplanted. Therefore, nursery‐reared fragments of P. damicornis between 2 and 4 cm are the most appropriate for use in restoration projects.     

Adhering ability of <Emphasis Type="Italic">Stenotrophomonas maltophilia</Emphasis> is dependent on growth conditions

The growth conditions are known to influence the bacterial adhesion to different kinds of surfaces. In the present study the adhering ability of S. maltophilia, on growth in nutrient rich media (Tryptic Soy Broth (TSB)) and minimal media (Luria Bertani (LB)) was checked by viable cell count and spectrophotometric method. TSB grown S. maltophilia showed higher adhesion compared to bacteria grown in LB broth, to both biotic and abiotic surfaces. However, when bacteria were grown in LB broth supplemented with different concentrations of glucose, under aerobic conditions, the bacteria grown at lower glucose concentration (2 gm/l) showed maximumadhesion to abiotic surfaces (polystyrene microliter plate) compared to biotic surfaces (mouse trachea, mouse tracheal mucus and HEp-2 cells line). Maximum adhesion to biotic surfaces was seen with cells grown at 4 gm/l of glucose concentration. On the contrary if the cell was grown under microaerophilic conditions maximum adhesion to abiotic and biotic surfaces was achieved with bacteria grown at 1 gm/l and 2 gm/l of glucose concentration respectively. A negative correlation was observed between glucose concentrations and pH of media, the latter declined faster under microaerophilic conditions as compared to aerobic condition.     

Aromatic plants in nests of the blue tit <Emphasis Type="Italic">Cyanistes caeruleus</Emphasis> protect chicks from bacteria

Several bird species add fresh fragments of plants which are rich in volatile secondary compounds to their nests. It has been suggested, although never tested, that birds use fresh plants to limit the growth of nest microorganisms. On Corsica, blue tits (Cyanistes caeruleus) incorporate fresh fragments of aromatic plants into their nests. These plants do not reduce infestation by nest ectoparasites, but have been shown to improve growth and condition of chicks at fledging. To understand the mechanisms underlying such benefits, we experimentally tested the effects of these plants on the bacteria living on blue tits. Aromatic plants significantly affected the structure of bacterial communities, in particular reducing bacterial richness on nestlings. In addition, in this population where there is a strong association between bacterial density and infestation by blood-sucking Protocalliphora blow fly larvae, these plants reduced bacterial density on the most infested chicks. Aromatic plants had no significant effect on the bacteria living on adult blue tits. This study provides the first evidence that fresh plants brought to the nests by adult birds limit bacterial richness and density on their chicks.