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PubMed1976

Effects of frontal polar cortical ablation and cycloheximide on ethanol tolerance in rats.

Thirty adult male Wister rats were pretrained to criterion on the moving belt test, and then made tolerant to ethanol by daily administration of increasing doses over a period of 3 weeks. After a one-month recovery period, they were divided into 3 groups, subjected to bilateral frontal polar cortical ablations, sham-operation and no operation respectively. After postoperative recovery, the cycle of ethanol treatment and testing was repeated. Only the lesioned group failed to reacquire tolerance. A pilot experiment showed that occipital cortical ablations also prevented tolerance. In a second experiment 32 rats, which had similarly undergone and then recovered from an initial period of ethanol tolerance, were divided into 4 groups which received daily treatment with sucrose plus cycloheximide (0.3 mg/kg), sucrose plus saline, ethanol plus cycloheximide, and ethanol plus saline respectively. Only the ethanol plus saline group re-acquired tolerance. Tt is concluded that frontal polar cortical lesions and cycloheximide can both block the development of tolerance to ethanol in animals previously shown to be capable of developing such tolerance.

Animals↗

PubMed2004

Expression of the Nicotiana protein kinase (NPK1) enhanced drought tolerance in transgenic maize.

Drought is one of the most important abiotic stresses affecting the productivity of maize. Previous studies have shown that expression of a mitogen-activated protein kinase kinase kinase (MAPKKK) gene activated an oxidative signal cascade and led to the tolerance of freezing, heat, and salinity stress in transgenic tobacco. To analyse the role of activation of oxidative stress signalling in improving drought tolerance in major crops, a tobacco MAPKKK (NPK1) was expressed constitutively in maize. Results show that NPK1 expression enhanced drought tolerance in transgenic maize. Under drought conditions, transgenic maize plants maintained significantly higher photosynthesis rates than did the non-transgenic control, suggesting that NPK1 induced a mechanism that protected photosynthesis machinery from dehydration damage. In addition, drought-stressed transgenic plants produced kernels with weights similar to those under well-watered conditions, while kernel weights of drought-stressed non-transgenic control plants were significantly reduced when compared with their non-stressed counterparts.

Disasters↗

PubMed2003

Tolerability and cardiovascular complications of outpatient diagnostic minihysteroscopy compared with conventional hysteroscopy.

STUDY OBJECTIVE: To assess acceptability and cardiovascular complications of hysteroscopy performed with minihysteroscopes compared with those performed with conventional hysteroscopes. DESIGN: Prospective, randomized clinical trial (Canadian Task Force classification I). SETTING: Academic research center. PATIENTS: One hundred women with abnormal uterine bleeding. INTERVENTIONS: Hysteroscopy with a 3.5-mm minihysteroscope or conventional 5-mm endoscope with no anesthesia. MEASUREMENTS AND MAIN RESULTS: Duration of examinations, pain, and occurrence of vasovagal reactions were recorded. Pain was assessed by visual analog scale ranging from zero to 20 before (pain expectancy) and at the end of the procedure. Occurrence of vasovagal reactions was assessed by monitoring blood pressure and pulse rate at 1-minute intervals during the procedure. A heart rate of less than 60/minute or a reduction greater than 20% compared with baseline was considered a vasovagal reaction; similarly, a reduction in blood pressure exceeding baseline value by 20% was considered a result of vagal stimulation. Mean duration was shorter for minihysteroscopy than for conventional hysteroscopy. The mean (SD) level of pain experienced during minihysteroscopy also was significantly lower (0.76 +/- 0.65 vs 1.46 +/- 0.86, 95% CI-1.0-0.4, p <0.0001). The number of instrumentally recorded (1 vs 11 cases) and clinical vasovagal reactions (0 vs 6 cases) was also significantly lower in the minihysteroscopy group than in the conventional hysteroscopy group (p <0.002 and <0.02, respectively). CONCLUSION: New-generation minihysteroscopes make hysteroscopy easier and less painful, and carry a lower risk of vasovagal reactions than hysteroscopy performed with conventional instruments. In our experience, minihysteroscopy with vaginoscopic approach and saline distention is well tolerated, effective, and a true outpatient procedure.

Ambulatory Care↗

PubMed2001

Modeling the current-voltage characteristics of charophyte membranes. II. The effect of salinity on membranes of Lamprothamnium papulosum.

Lamprothamnium is a salt-tolerant charophyte that inhabits a broad range of saline environments. The electrical characteristics of Lamprothamnium cell membranes were modeled in environments of different salinity: full seawater (SW), 0.5 SW, 0.4 SW, and 0.2 SW. The cells were voltage-clamped to obtain the I/V (current-voltage) and G/V (conductance-voltage) profiles of the cell membranes. Cells growing at the different salinities exhibited one of three types of I/V profiles (states): pump-, background- and K(+)-states. This study concentrates on the pump- and background-states. Curved (pump-dominated) I/V characteristics were found in cells with resting membrane PDs (potential differences) of -219 +/- 12 mV (in 0.2 SW: 6 cells, 16 profiles), -161 +/- 12 mV (in 0.4 SW: 6 cells, 7 profiles), -151 +/- 12 mV (in 0.5 SW: 6 cells, 12 profiles) and -137 +/- 12 mV (in full SW: 8 cells, 13 profiles). The linear I/V characteristics of the background-state were found in cells with resting PDs of -107 +/- 12 mV (in 0.4 SW: 7 cells, 12 profiles), -108 +/- 12 mV (in 0.5 SW: 7 cells, 10 profiles) and -104 +/- 12 mV (in full SW: 3 cells, 5 profiles). The resting conductance (G) of the cells progressively increased with salinity, from 0.5 S x m(-2) (in 0.2 SW) to 22.0 S x m(-2) (in full SW). The pump peak conductance only rose from 2 S x m(-2) (0.2 SW) to 5 S x m(-2) (full SW), accounting for the increasingly depolarized resting PD observed in cells in more saline media. Upon exposure to hypertonic medium, both the pump and an inward K+ rectifier were stimulated. The modeling of the I/V profiles identified the inward K+ rectifier as an early electrical response to hypertonic challenge.

Cell Membrane↗

PubMed2006

Expression analysis of barley (Hordeum vulgare L.) during salinity stress.

Barley (Hordeum vulgare L.) is a salt-tolerant crop species with considerable economic importance in salinity-affected arid and semiarid regions of the world. In this work, barley cultivar Morex was used for transcriptional profiling during salinity stress using a microarray containing approximately 22,750 probe sets. The experiment was designed to target the early responses of genes to a salinity stress at seedling stage. We found a comparable number of probe sets up-regulated and down-regulated in response to salinity. The differentially expressed genes were broadly characterized using gene ontology and through expression-based hierarchical clustering to identify interesting features in the data. A prominent feature of the response to salinity was the induction of genes involved in jasmonic acid biosynthesis and genes known to respond to jasmonic acid treatment. A large number of abiotic stress (heat, drought, and low temperature) related genes were also found to be responsive to salinity stress. Our results also indicate osmoprotection to be an early response of barley under salinity stress. Additionally, we compared the results of our studies with two other reports characterizing gene expression of barley under salinity stress and found very few genes in common.

Cyclopentanes↗

PubMed1999

Salt-sensitivity classification in normotensive adults.

The objectives of this study were to assess the reliability, sensitivity and specificity of salt-sensitivity classification in normotensive adults and to determine the predictive power of four clinical indices for salt-sensitivity. A total of 66 healthy, normotensive, free-living adults were administered 11-day salt-sensitivity diagnostic dietary salt challenges on two occasions to permit assessment of classification test-retest reliability. An oral glucose tolerance test, an acute saline loading test, gustatory testing and determination of salivary flow and sodium concentration were carried out to assess (by correlation analysis) their predictive power for salt-sensitivity. Following these procedures, 21 participants followed a reduced-sodium diet for 4 months, during which blood pressure was monitored monthly to allow evaluation of salt-sensitivity classification sensitivity and specificity. Regression was used to develop a predictive model for salt-sensitivity. Salt-sensitivity classification was not highly reliable (kappa-value=0.38), sensitive (0.73) or specific (0.60). No single index was highly predictive of classification status, but a model composed of five indices accounted for 92% of the variance in blood pressure response to acute salt challenge. The dietary salt challenge procedure used here for salt-sensitivity classification of normotensive adults had low test-retest reliability. While a battery of easily measured attributes may facilitate rapid salt-sensitivity classification, such a diagnosis provides only limited insight regarding blood pressure responsiveness to chronic dietary salt restriction in normotensive adults.

Adult↗

PubMed1991

Selenium accumulation and selenium tolerance of salt grass from soils with elevated concentrations of Se and salinity.

Biomass production, selenium accumulation, and the role of the bioextraction of selenium by salt grass (Distichlis spicata L.) in soils with elevated concentrations of Se and salinity at Kesterson, California, were studied. Salt grass contributed more than 80% vegetative coverage and 90% dry weight in the grassland communities where the soil Se concentrations were 100 times (1000 to 3000 micrograms kg-1) higher than the Se concentrations found in soils of the control sites. No evidence for evolution of Se tolerance was found in the salt grass populations. The successful colonization of salt grass in the soil with elevated Se and salinity is attributable to the presence of high concentrations of soil sulfate. Salt grass accumulated less Se than other salt-tolerant plant species existing in the same area, and no predation of animals and insects on salt grass has been noticed. Salt grass can transpire substantial amounts of volatile Se through its plant tissue. Under field conditions, a 1-m2 salt grass plot may produce 180 micrograms volatile selenium per day. However, no reduction of soil Se concentration in the salt grass habitat was detected over a period of 1 year. A long-term monitoring of Se status is needed in order to make predictions of the effectiveness of efforts to clean up Se-contaminated soils through the use of native plant species.

Chlorides↗

PubMed2026

Phenotypic and phylogenomic characterization of Lactococcus garvieae isolates from rainbow trout (Oncorhynchus mykiss) in Türkiye.

Lactococcosis is an important bacterial disease of farmed fish and causes substantial economic losses in rainbow trout (Oncorhynchus mykiss) aquaculture. In this study, Lactococcus garvieae isolates recovered from rainbow trout farms in Türkiye were characterized using phenotypic, molecular, and phylogenomic methods. Among 32 presumptive Lactococcus isolates recovered from 127 dead rainbow trout, four were confirmed as L. garvieae and exhibited identical biochemical characteristics, Pulsed Field Gel Electrophoresis (PFGE) profiles, and broad growth tolerance across different pH, salinity, and temperature conditions. All isolates were presumptively classified as resistant to ciprofloxacin and florfenicol, while remaining susceptible to tetracycline and penicillin. Based on the AMR profiles, strain LG2, which exhibited the most susceptible antimicrobial profile among the isolates, was selected for whole-genome sequencing (WGS). WGS of the representative isolate LG2 generated a single 2,214,687-bp chromosomal contig with 38.5% GC content and 99.0% BUSCO completeness. In silico PCR assigned LG2 to serotype I, and the genome contained an intact capsule-associated cps/kps locus. The chromosomal lsa(D) determinant and an mdt(A)-like efflux-associated gene were detected, whereas no plasmid replicons or acquired quinolone or florfenicol resistance genes were identified, indicating discordance between the phenotypic and genomic AMR results. Taxonomic verification of 236 publicly available Lactococcus assemblies yielded 41 verified public L. garvieae genomes, which, together with LG2, formed a 42-genome within-species dataset. LG2 was most closely related to the Turkish isolate OS-37, sharing 99.96% ANI and differing by three core SNPs; both belonged to ST109, whereas the other Turkish isolates belonged to ST139. cgMLST identified a conserved genomic backbone, while pan-genome analysis identified 5,655 gene clusters and an open pan-genome characterized by a large cloud-gene fraction. These findings demonstrate the importance of species verification in Lactococcus population genomics and reveal substantial accessory-genome diversity within L. garvieae. The genomic features of LG2 provide a basis for future pathogenicity and immunogenicity studies, although experimental validation is required. Overall, these findings highlight the importance of local genomic surveillance for understanding L. garvieae population structure and provide a genomic framework for future region-specific vaccine research.

Animals↗

PubMed1994

Effects of chronic treatment with triazolam on operant responding in rats.

The aims of the present study were to investigate the effect of the benzodiazepine antagonist, flumazenil, on operant responding in rats treated chronically with the short-acting hypnotic triazolam and to study the consequence of chronic triazolam treatment on the time course of effects of triazolam and zolpidem. Zolpidem is an imidazopyridine with a pharmacological and behavioral profile that differs from that of the benzodiazepine hypnotics. Rats were treated with saline or triazolam (1 or 3 mg/kg) twice daily for 5 days and were tested daily 1, 3, 5.5 or 7.5 h after injection. In addition, on the 5th day of chronic treatment all rats were injected with flumazenil (10 mg/kg) 10 min before session. The time course of effects of triazolam and zolpidem was determined after cessation of repeated saline or triazolam treatment. Tolerance to the depressant effect of 1 mg/kg of triazolam developed during long-term administration. Flumazenil decreased operant responding in rats pretreated with triazolam. The effect was statistically significant when rats had received 1 mg/kg of triazolam 3 h before the session or 3 mg/kg of triazolam 3, 5.5 or 7.5 h before the session. After cessation of chronic treatment, rats pretreated chronically with 3 mg/kg of triazolam displayed decreased sensitivity to triazolam and to 10 mg/kg but not 3 mg/kg of zolpidem. The present results indicate that chronic treatment with triazolam induces tolerance to the rate-decreasing effect of the drug and dependence as measured by flumazenil-induced disruption of operant responding. The limited degree of cross-tolerance between zolpidem and triazolam may suggest that their pharmacological mechanisms of action are distinct.

Animals↗

PubMedDate not supplied

Antinociceptive cross-tolerance between [D-Arg2]-dermorphin tetrapeptide analogs and morphine.

Cross-tolerance between [D-Arg2]-dermorphin tetrapeptide analogs and morphine with respect to antinociception was examined in the present set of experiments. Systemic administration of H-Tyr-D-Arg-Phe-Gly-NH2 (TDAPG-NH2), H-Tyr-D-Arg-Phe-beta-Ala-OH (TDAPA) or morphine over a period of 5 days produced the development of tolerance. In the cross-tolerance study, antinociception after subcutaneous (SC), intracerebroventricular (ICV) and intrathecal (IT) administrations of TDAPG-NH2 and TDAPA in morphine-tolerant mice was not significantly different from their respective effects in saline-pretreated control mice. A marked tolerance to SC- and ICV-administered morphine was seen in mice made tolerant to TDAPG-NH2 and TDAPA. However, IT administration of morphine produced no significant decrement in the antinociceptive activity in mice made tolerant to TDAPG-NH2 and TDAPA. These data indicate that [D-Arg2]-dermorphin tetrapeptide analogs can produce significant antinociception in morphine-tolerant mice.

Amino Acid Sequence↗

PubMed1995

The effect of continuous morphine analgesia on chronic thermal hyperalgesia due to sciatic constriction injury in rats.

We employed hindfoot withdrawal latencies to radiant heat to assess the analgesic effect of prolonged morphine infusion on thermal hyperalgesia induced by chronic constriction injury (CCI) of the rat sciatic nerve. All CCI rats developed thermal hyperalgesia while sham-operated animals did not. Continuous systemic infusion of morphine dose-dependently reversed the thermal hyperalgesia in the CCI rats. In contrast, thermal hyperalgesia persisted in saline-treated CCI rats. Tolerance to morphine's analgesic effect did not develop over a period of seven days of morphine infusion, which is considered long-term for animal models. These data suggest that morphine acts rapidly and effectively to reduce behavioral signs of hyperalgesia in rats with sciatic CCI, without the concomitant development of tolerance. Scheduled administration of morphine might be an appropriate treatment regimen for relief of neuropathic pain, and the infrequent use of opioids in equivalent human clinical pain syndromes due to fear of opioid unresponsiveness and tolerance might need to be re-evaluated.

Analgesia↗

PubMed2001

Utility and limitations of biochemical parameters in the evaluation of hyponatremia in the elderly.

We evaluated in 110 consecutive elderly hyponatremic patients the value of traditional clinical and biochemical data and the place of a test infusion of 2 liters isotonic saline over 24 hours, in establishing the etiology of the hyponatremia. The causes of hyponatremia were as follows: 31% SIADH patients, 23% patients with hyponatremia due to diuretics, 18% potomania patients, 15% salt depleted patients, 5% salt depleted SIADH patients, 5% patients with a salt loosing syndrome and 3% patients with hyponatremia of unknown origin. Several salt depleted (SD) and SIADH patients could be confounded. Usually, adults with SIADH show plasma uric acid values <4 mg/dL. In our elderly population, 41% of SD patients presented plasma uric acid <4 mg/dL, while 27% of SIADH patients showed plasma uric acid >4 mg/dL. Eighty-two percent of SD patients appeared to have plasma urea levels >30 mg/dL, but this was also the case in 21% of SIADH patients. Twenty-nine of the SD patients presented a urinary sodium >30 mEq/L, but all had fractional sodium excretion (FENa) lower than 0.5%. However, in SIADH, 42% of the patients presented also FENa <0.5%. Fractional excretion of urea (FE urea) below 50% was encountered in 82% of SD patients and FE urea above 50% in only 52% of the SIADH patients. Plasma renin and aldosterone values were poorly discriminative. A test infusion with 2 liters isotonic saline over 24 hours allowed a correct classification of all the patients. In about 2/3 of the population, administration of isotonic saline could be considered as useful (SD, most diuretic patients, potomania patients, salt loosing syndrome patients and some SD SIADH patients). A plasma sodium (PNa) increase of at least 5 mEq/L 24 hours after saline infusion has been suggested as highly suggestive of SD. Nevertheless, 29% of our SD patients did not increase their PNa level by 5 mEq/L or more, while 30% of our SIADH patients did. PNa improved after 2 liters isotonic saline over 24 hours in 90 patients (85%) as opposed to 12 others (9 SIADH and 3 diuretic patients), decreasing their plasma sodium. The isotonic saline infusion test, only allows a reliable classification of hyponatremia, as far as both PNa and sodium excretion were taken into account. In the SIADH group, 6 patients (5%) presented initially manifest solute depletion and retained the 2 liters isotonic saline before developping inappropriate natriuresis. Six patients showed a transient salt loosing syndrome with high fractional potassium excretion (FEK) and high calciuria, which differentiates them from thiazide patients presenting also high FEK, but low calciuria. These patients were also polyuric at admission. The saline infusion was well tolerated in all but 2 patients, developing mild pulmonary congestion at the end of the test infusion.

Aged↗

PubMed2004

The hyperthermophilic origin of life revisited.

We revisit the case for the hyperthermophilic scenario for the origin of life and the last common ancestor. Evidence includes studies of phylogenetic trees, rRNA, G and C content, hyperthermophilic proteins, correlations between maximal temperature tolerances and genetic distances, saline stabilization of DNA/RNA, and the inferred climatic temperatures of the early Earth. Although some doubts remain, the case for hot biogenesis and the last common ancestor has gotten stronger.

Archaea↗

PubMed2005

A MAPK gene from Dead Sea fungus confers stress tolerance to lithium salt and freezing-thawing: Prospects for saline agriculture.

The Dead Sea is one of the most saline lakes on earth ( approximately 340 g/liter salinity) and is approximately 10 times saltier than the oceans. Eurotium herbariorum, a common fungal species, was isolated from its water. EhHOG gene, encoding a mitogen-activated protein kinase (MAPK) that plays an essential role in the osmoregulatory pathway in yeast and many other eukaryotes, was isolated from E. herbariorum. The deduced amino acid sequences of EhHOG indicated high similarity with homologous genes from Aspergillus nidulans, Saccharomyces cerevisiae, and Schizosaccharomyces pombe and contained a TGY motif for phosphorylation by MAPK kinase. When EhHOG was expressed in S. cerevisiae hog1Delta mutant, the growth and aberrant morphology of hog1Delta mutant was restored under high osmotic stress condition. Moreover, intracellular glycerol content in the transformant increased to a much higher level than that in the mutant during salt-stress situations. hog1Delta mutant complemented by EhHOG outperformed the wild type or had higher genetic fitness under high Li(+) and freezing-thawing conditions. The present study revealed the putative presence of a high-osmolarity glycerol response (HOG) pathway in E. herbariorum and the significance of EhHOG in osmotic regulation, heat stress, freeze stress, and oxidative stress. The Dead Sea is becoming increasingly more saline while the fungi living in it evolutionarily adapt to its high-saline environment, particularly with the extraordinarily high Li(+) concentration. The Dead Sea is potentially an excellent model for studies of evolution under extreme environments and is an important gene pool for future agricultural genetic engineering prospects.

Agriculture↗

PubMed2004

Reconciling geography and genealogy: phylogeography of giant freshwater prawns from the Lake Carpentaria region.

There is convincing geological evidence for the historical existence of an ancient lake on the Australian-New Guinea continental shelf during the late Pleistocene. Lake Carpentaria was a vast fresh- to brackishwater lake that would presumably have provided habitat for, and facilitated gene flow among, aquatic taxa that tolerate low to moderate salinities in this region. Moreover, it has been argued that the outflow of Papua New Guinea's Fly River was diverted westward into Lake Carpentaria during this period, although this hypothesis is controversial. We predicted that these events, if a true history, would have promoted gene flow and population growth via range-expansion events in the giant freshwater prawn (Macrobrachium rosenbergii) and restricted gene flow subsequently by way of a vicariant event as sea levels rose during the late Pleistocene, and a marine environment replaced Lake Carpentaria. We tested these hypotheses using phylogeographical and phylogenetic analyses of mitochondrial DNA variation in M. rosenbergii populations sampled from the Lake Carpentaria region. Our results support the hypothesis that Lake Carpentaria facilitated gene flow among populations of M. rosenbergii that are today isolated, but contest claims of a westward diversion of the Fly River. We inferred the timing of initial expansion in the 'Lake Carpentaria lineage' and found the timing of this event to be broadly concordant with geological dating of the formation of Lake Carpentaria. Reconciling geological and molecular data, as presented here, provides a powerful framework for investigating the influence of historical earth history events on the distribution of biological (i.e. molecular) diversity.

Animals↗

PubMed1979

Seasonal and geographic distribution of luminous bacteria in the eastern mediterranean sea and the gulf of elat.

Luminous bacteria in the Mediterranean Sea and the Gulf of Aqaba-Elat have different distribution patterns. In the Mediterranean Sea, Beneckea harveyi is present all year round, with different subtypes alternating in summer and winter; Photobacterium fischeri was only present during the winter. In the Gulf of Elat, P. leiognathi is present throughout the water column in similar densities during the entire year. This constancy in distribution is presumably due to the near-constancy in water temperature. In summer, Photobacterium leiognathi is replaced by B. harveyi in coastal surface waters. In the hypersaline Bardawil lagoon, only B. harveyi types are present. P. fischeri, a major component of the Mediterranean Sea winter communities, is absent from the lagoon. Luminous Beneckea strains show a great diversity in properties, e.g. temperature range for growth, sensitivity to infection by phages, sensitivity to attack by Bdellovibrio strains, and differences in tolerance to high-salinity shock. Therefore, subdivision of the taxonomic cluster of B. harveyi into subtypes is indicated. The composition of the luminous bacteria communities may serve as indicators of different marine water bodies. The symbiotic luminous bacteria of the light organ of the common Gulf of Elat fish, Photoblepharon palbebratus steinitzi, is different from any of the types described.

Journal Article↗

PubMed1986

Bacterial physiological diversity in the rhizosphere of range plants in response to retorted shale stress.

Bacterial populations were isolated from the soil-root interface and root-free regions of Agropyron smithii Rydb. and Atriplex canescens (Pursh) Nutt. grown in soil, retorted shale, or soil over shale. Bacteria isolated from retorted shale exhibited a wider range of tolerance to alkalinity and salinity and decreased growth on amino acid substrates compared with bacteria from soil and soil-over-shale environments. Exoenzyme production was only slightly affected by growth medium treatment. Viable bacterial populations were higher in the rhizosphere and rhizoplane of plants grown in retorted shale than in plants grown in soil or soil over shale. In addition, a greater number of physiological groups of rhizosphere bacteria was observed in retorted shale compared with soil alone. Two patterns of community similarity were observed in comparisons of bacteria from soil over shale with those from soil and retorted-shale environments. Root-associated populations from soil over shale had a higher proportion of physiological groups in common with those from the soil control than with those from the retorted-shale treatment. However, in non-rhizosphere populations, bacterial groups from soil over shale more closely resembled the physiological groups from retorted shale.

Journal Article↗

PubMed2004

Bacterium-based NO2- biosensor for environmental applications.

A sensitive NO2- biosensor that is based on bacterial reduction of NO2- to N2O and subsequent detection of the N2O by a built-in electrochemical N2O sensor was developed. Four different denitrifying organisms lacking NO3- reductase activity were assessed for use in the biosensor. The relevant physiological aspects examined included denitrifying characteristics, growth rate, NO2- tolerance, and temperature and salinity effects on the growth rate. Two organisms were successfully used in the biosensor. The preferred organism was Stenotrophomonas nitritireducens, which is an organism with a denitrifying pathway deficient in both NO3- and N2O reductases. Alternatively Alcaligenes faecalis could be used when acetylene was added to inhibit its N2O reductase. The macroscale biosensors constructed exhibited a linear NO2- response at concentrations up to 1 to 2 mM. The detection limit was around 1 microM NO2-, and the 90% response time was 0.5 to 3 min. The sensor signal was specific for NO2-, and interference was observed only with NH2OH, NO, N2O, and H2S. The sensor signal was affected by changes in temperature and salinity, and calibration had to be performed in a system with a temperature and an ionic strength comparable to those of the medium analyzed. A broad range of water bodies could be analyzed with the biosensor, including freshwater systems, marine systems, and oxic-anoxic wastewaters. The NO2- biosensor was successfully used for long-term online monitoring in wastewater. Microscale versions of the NO2- biosensor were constructed and used to measure NO2- profiles in marine sediment.

Alcaligenes faecalis↗