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1.
A new amperometric enzyme-linked immunoassay for specific enumeration of Nitrobacter has been developed. This assay uses an electrode made of glassy carbon, on which the immunological reaction is carried out.
The method is based on a competitive immunoassay principle, utilising monoclonal primary antibody and alkaline-phosphatase-labelled
secondary antibody. The enzyme substrate 5-bromo-4-chloro-3-indolyl phosphate generates an electroactive product which is
amperometrically detected. The effects of different parameters on the performance of the sensor have been studied. Quantitative
detection of Nitrobacter using the immunosensor has been compared to a previously developed enzyme-linked immunosorbent assay showing compatible results.
In addition, the overall assay time can be shortened with this new sensor. A detection limit of approximately 3 × 106
Nitrobacter cells/ml was obtained.
Received: 27 May 1998 / Received revision: 28 August 1998 / Accepted: 28 August 1998 相似文献
2.
Dimitry Y. Sorokin Gerard Muyzer Thorsten Brinkhoff J. Gijs Kuenen M. S. M. Jetten 《Archives of microbiology》1998,170(5):345-352
Five strains of lithotrophic, nitrite-oxidizing bacteria (AN1-AN5) were isolated from sediments of three soda lakes (Kunkur
Steppe, Siberia; Crater Lake and Lake Nakuru, Kenya) and from a soda soil (Kunkur Steppe, Siberia) after enrichment at pH
10 with nitrite as sole electron source. Morphologically, the isolates resembled representatives of the genus Nitrobacter. However, they differed from recognized species of this genus by the presence of an additional S-layer in their cell wall
and by their unique capacity to grow and oxidize nitrite under highly alkaline conditions. The influence of pH on growth of
one of the strains (AN1) was investigated in detail by using nitrite-limited continuous cultivation. Under such conditions,
strain AN1 was able to grow at a broad pH range from 6.5 to 10.2, with an optimum at 9.5. Cells grown at pH higher than 9
exhibited a clear shift in the optimal operation of the nitrite-oxidizing system towards the alkaline pH region with respect
to both reaction rates and the affinity. Cells grown at neutral pH values behaved more like neutrophilic Nitrobacter species. These data demonstrated the remarkable potential of the new nitrite-oxidizing bacteria for adaptation to varying
alkaline conditions. The 16S rRNA gene sequences of isolates AN1, AN2, and AN4 showed high similarity (≥ 99.8%) to each other,
and to sequences of Nitrobacter strain R6 and of Nitrobacter winogradskyi. However, the DNA-DNA homology in hybridization studies was too low to consider these isolates as new strains. Therefore,
the new isolates from the alkaline habitats are described as a new species of the genus Nitrobacter, N. alkalicus, on the basis of their substantial morphological, physiological, and genetic differences from the recognized neutrophilic
representatives of this genus.
Received: 3 April 1998 / Accepted: 2 July 1998 相似文献
3.
Abstract
Nitrification in freshwater, a key process in the nitrogen cycle, is now well known to take place predominantly on suspended
particles and in sediment. Nitrobacter is the most commonly isolated nitrite oxidizing bacteria from water environments. Three methods for counting nitrite oxidizing
communities (especially Nitrobacter) in sediment were investigated: MPN-Griess, fluorescent antibodies (immunofluorescence), and a more recent molecular method
coupling specific DNA amplification by PCR and statistical MPN quantification. After preliminary adjustments of the MPN-PCR
technique, the detection level and the yield of each method were determined by inoculating a sediment with a pure Nitrobacter culture. The best recovery yield was obtained with the immunofluorescence technique (21.3%) and the lowest detection level
was reached with the MPN-Griess method (103
Nitrobacter/g dry weight sediment). The MPN-PCR method resulted in the lowest recovery yields and needs further adaptation to become
a reliable and precise tool for investigations of nitrifying bacteria in sediment.
Received: 6 July 1998; Accepted: 17 December 1998 相似文献
4.
Bacterial physiological responses to toluene exposure were investigated in five reference pseudomonad strains that express
different toluene degradation pathways: Pseudomonas putida mt-2, Pseudomonas putida F1, Burkholderia cepacia G4, Burkholderia pickettii PKO1, and Pseudomonas mendocina KR1. The intact phospholipids of these archetypes, grown with and without toluene, were characterized using liquid chromatography/electrospray
ionization/mass spectrometry. All strains showed significant changes in phospholipid content and composition as an adaptive
response to toluene exposure, as well as considerable diversity in response mechanisms. For example, the phospholipid content
of toluene-grown PKO1, F1, and KR1 were 10.9–34.7% of that found in succinate-grown strains, while the phospholipid content
of mt-2 and G4 increased by 56% and 94%, respectively, when grown on toluene. In addition, PKO1, F1, and mt-2 responded to
the presence of toluene by synthesizing more phosphatidylglycerol, whereas G4 and KR1 synthesized phospholipids with polyunsaturated
fatty acids (C18:2) on one or both of the sn-2 positions. These changes in phospholipid composition and concentration probably reflect the sensitivity and degree of tolerance
of these strains to toluene, and suggest that different mechanisms are utilized by dissimilar bacteria to maintain optimal
lipid ordering in the presence of such environmental pollutants.
Received: 13 October 1999 / Received revision: 16 February 2000 / Accepted: 25 February 2000 相似文献
5.
Thirty-seven rhizobium strains, isolated from root nodules of Astragalus cicer (L.) (cicer milkvetch) deriving from different geographic regions, were compared with the representative strains of the known
rhizobial species and genera by numerical analysis of phenotypic characteristics. Our results indicated that Astragalus cicer rhizobia were related to the bacteria of Mesorhizobium species and formed two major phena. One phenon, localized on Mesorhizobium loti branch, contained strains from Poland. Another cluster, placed in the vicinity of M. tianshanense, M. mediterraneum, M. ciceri, and M. huakuii, comprised cicer milkvetch nodule isolates from Canada, Ukraine, and one strain from Poland. The relationship of Astragalus cicer microsymbionts to bacteria of the Mesorhizobium species was also supported by phage typing.
Received: 10 February 2000 / Accepted: 8 March 2000 相似文献
6.
Behavior of Variable V3 Region from 16S rDNA of Lactic Acid Bacteria in Denaturing Gradient Gel Electrophoresis 总被引:5,自引:0,他引:5
Separation of amplified V3 region from 16S rDNA by denaturing gradient gel electrophoresis (DGGE) was tested as a tool for
differentiation of lactic acid bacteria commonly isolated from food. Variable V3 regions of 21 reference strains and 34 wild
strains referred to species belonging to the genera Pediococcus, Enterococcus, Lactococcus, Lactobacillus, Leuconostoc, Weissella, and Streptococcus were analyzed. DGGE profiles obtained were species-specific for most of the cultures tested. Moreover, it was possible to
group the remaining LAB reference strains according to the migration of their 16S V3 region in the denaturing gel. The results
are discussed with reference to their potential in the analysis of LAB communities in food, besides shedding light on taxonomic
aspects.
Received: 2 August 2000 / Accepted: 5 September 2000 相似文献
7.
A wireless immunosensor for the detection of Mycoplasma genitalium was fabricated by immobilizing polyclonal antibody onto the surface of a magnetostrictive strip. In response to a time-varying magnetic field, the immunosensor longitudinally vibrates at a resonance frequency, emitting magnetic flux that can be remotely detected by a pickup coil. No physical connections between the immunosensor and the detection system are required, facilitating wireless aseptic operation. The binding of M. genitalium to the immunosensor surface resulted in a decrease in the resonance frequency of the immunosensor. When solutions with varying concentrations of the bacteria were tested, the shift of the resonance frequency was proportional to the concentration of M. genitalium. Under the optimized conditions, the linear range for the determination of M. genitalium was 2.0 × 103 to 2.9 × 104 color change units (ccu)/ml with a detection limit of 3.4 × 102 ccu/ml. The immunosensor was successfully applied to real samples containing M. genitalium with results similar to those previously obtained by the color change unit method. 相似文献
8.
Wang F Liu Y Wang J Zhang Y Yang H 《Journal of industrial microbiology & biotechnology》2012,39(4):595-604
The effects of growth type, including attached growth, suspended growth, and combined growth, on the characteristics of communities
of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were studied in three lab-scale Anaerobic/Anoxicm-Oxicn (AmOn) systems. These systems amplified activated sludge, biofilms, and a mixture of activated sludge and biofilm (AS-BF).
Identical inocula were adopted to analyze the selective effects of mixed growth patterns on nitrifying bacteria. Fluctuations
in the concentration of nitrifying bacteria over the 120 days of system operation were analyzed, as was the composition of
nitrifying bacterial community in the stabilized stage. Analysis was conducted using polymerase chain reaction-denaturing
gradient gel electrophoresis (PCR-DGGE) and real-time PCR. According to the DGGE patterns, the primary AOB lineages were Nitrosomonas europaea (six sequences), Nitrosomonas oligotropha (two sequences), and Nitrosospira (one sequence). The primary subclass of NOB community was Nitrospira, in which all identified sequences belonged to Nitrospira moscoviensis (14 sequences). Nitrobacter consisted of two lineages, namely Nitrobacter
vulgaris (three sequences) and Nitrobacter alkalicus (two sequences). Under identical operating conditions, the composition of nitrifying bacterial communities in the AS-BF system
demonstrated significant differences from those in the activated sludge system and those in the biofilm system. Major varieties
included several new, dominant bacterial sequences in the AS-BF system, such as N. europaea and Nitrosospira and a higher concentration of AOB relative to the activated sludge system. However, no similar differences were discovered
for the concentration of the NOB population. A kinetic study of nitrification demonstrated a higher maximum specific growth
rate of mixed sludge and a lower half-saturation constant of mixed biofilm, indicating that the AS-BF system maintained relatively
good nitrifying ability. 相似文献
9.
To study the ecology of chemoautotrophic nitrifying bacteria (Nitrobacter), the immunofluorescence technique has been used. Fluorescent antibodies againstNitrobacter winogradskyi andNitrobacter agilis, the two known serotypes, have not labeled strains isolated from soils of the Lyon region (pH 8.1 and pH 4.7). The pure-culture isolates appeared to belong to the same genus, but to be serologically different from the reference strains. These results led us to question the diversity of strains ofNitrobacter in soils. 相似文献
10.
Low-substrate regulated microaerophilic behavior (LSRMB) was observed in 10–54% of the bacteria isolated from several fresh-water
lakes or ponds, subsurface soils, activated sludge, and Antarctic dry valley soils. Five Pseudomonas and two Bacillus type species showed LSRMB. A subsurface Pseudomonas jessenii strain was used as a model to show the metabolic interaction between substrate and oxygen concentrations, cell band movement,
and the appearance of unique stress lipids and proteins. When the oxygen in the P. jessenii culture medium was increased from 11% to 100% saturation under atmospheric condition, the concentration of 17:0 cyclopropane
fatty acid, a stress indicator, increased five-fold, and four unique proteins were also detected. This stress response occurred
only in low-substrate media. It is our hypothesis that LSRMB is a common but under-appreciated trait of many aquatic and soil
bacteria.
Received: 8 December 1999 / Accepted: 9 February 2000 相似文献
11.
The taxonomic positions of Nostoc and Anabaena strains are currently disputed. We selected three Nostoc and Anabaena strains, using the classic criteria of morphology and life cycle. DNA sequences of a part of the nifH gene were determined from these strains and aligned with homologous sequences from 10 other Nostoc/Anabaena strains in the public databases. Phylogenetic reconstructions were carried out to test the consistency of the taxonomic placement
of these strains. The phylogenetic trees do not separate these strains into distinct groups. Our results are in agreement
with other molecular-based phylogenies that also fail to differentiate the Nostoc-Anabaena groups. The data suggest that the currently recognized genera Nostoc and Anabaena may in fact belong within a single, broadly defined genus.
Received: 14 February 2000 / Accepted: 21 March 2000 相似文献
12.
Streptococcus thermophilus is used extensively for industrial fermentation of dairy products. Some strains of S. thermophilus are known to carry plasmids, and many of these plasmids are suspected of encoding low-molecular-weight heat stress proteins
(Hsps) that may aid in survival under stressful conditions. In order to confirm the presence and examine the similarity of
these low-molecular-weight Hsps, genes were identified and sequenced encoding Hsps on plasmids pER16 (4.5 kb), pER35 (10 kb),
and pER36 (3.7 kb) from three different strains of S. thermophilus. The plasmid replication proteins were also sequenced to examine their relatedness. Amino acid sequence comparisons of the
Hsps and of the replication proteins revealed a high degree of identity suggesting a common origin. Heat stress proteins enhance
the viability of bacteria in extreme environments, and the presence of an Hsp encoded on a plasmid may enhance survival of
S. thermophilus under harsh production conditions.
Received: 8 February 2000 / Accepted: 8 March 2000 相似文献
13.
A Neef R Witzenberger P Kämpfer 《Journal of industrial microbiology & biotechnology》1999,23(4-5):261-267
The increasing significance of members of the genus Sphingomonas in biotechnological applications has led to an increased interest in the diversity, abundance and ecophysiological potential
of this group of Gram-negative bacteria. This general focus provides a challenge to improve means for identification of sphingomonads;
eg molecular genetic methods for rapid and specific detection could facilitate screening of new isolates. Here, fluorescently
labeled oligonucleotide probes targeted against 16S rRNA were used to typify strains previously assigned to the genus. All
46 sphingomonads tested including type strains of 21 Sphingomonasspecies could be detected with a probe originally designed for the genus and all but one with a probe designed for the alpha-4
subgroup of the Proteobacteria. The two probes are suitable for direct detection of sphingomonads in pure and mixed cultures
as well as in environmental samples of unknown composition. The probes were used to identify sphingomonads in situ in activated sludge samples. Sphingomonads were rather abundant accounting for about 5–10% of the total cells in municipal
sludges. Distinct patterns in aggregation of the cells suggest that these organisms could be involved in the formation process
of sludge flocs.
Received 27 May 1999/ Accepted in revised form 22 August 1999 相似文献
14.
Microbial community structures in conventional activated sludge system and membrane bioreactor (MBR)
The microbial community structures of a conventional activated sludge and MBR systems treating the municipal wastewater were
studied using Fluorescent in-situ Hybridization (FISH) analysis to identify differences in both systems. The oligonucleotide probes specific for overall bacteria,
including α-, β-, and γ-subclasses of Proteobacteria, ammonia-oxidizing bacteria (Nitrosomonas), and nitrite-oxidizing bacteria (Nitrobacter) were used to compare the microbial community structure of both systems. A trend of less hybridization with bacteria-specific
probe EUB338 was observed in MBR systems operated under aerobic condition, compared to conventional activated sludge system.
The less hybridization trend with the probes could be associated with low ribosomal RNA (rRNA) content in the biomass, which
suggests that the biomass in the MBR system was not in a physiological state characteristic for growth due to low substrate
per unit biomass 相似文献
15.
Effects of ENU dosage on mouse strains 总被引:15,自引:0,他引:15
Monica J. Justice Don A. Carpenter Jack Favor Angelika Neuhauser-Klaus Martin Hrabé de Angelis Dian Soewarto Amy Moser Sabine Cordes Darla Miller Verne Chapman John S. Weber Eugene M. Rinchik Patricia R. Hunsicker William L. Russell Vernon C. Bode 《Mammalian genome》2000,11(7):484-488
The germline supermutagen, N-ethyl-N-nitrosourea (ENU), has a variety of effects on mice. ENU is a toxin and carcinogen as well as a mutagen, and strains differ
in their susceptibility to its effects. Therefore, it is necessary to determine an appropriate mutagenic, non-toxic dose of
ENU for strains that are to be used in experiments. In order to provide some guidance, we have compiled data from a number
of laboratories that have exposed male mice from inbred and non-inbred strains or their F1 hybrids to ENU. The results show that most F1 hybrid animals tolerate ENU well, but that inbred strains of mice vary in their longevity and in their ability to recover
fertility after treatment with ENU.
Received: 11 February 2000 / Accepted: 11 February 2000 相似文献
16.
Comparison of partial 16S rRNA gene sequences obtained from activated sludge bacteria 总被引:4,自引:0,他引:4
E. J. Vainio A. Moilanen T. T. Koivula D. H. Bamford J. Hantula 《Applied microbiology and biotechnology》1997,48(1):73-79
The cultivated and uncultivated bacterial communities of an activated sludge plant were studied. Two samples were taken and
a total of 516 bacterial isolates were classified into groups using their whole-cell protein patterns. The distribution of
bacteria into protein-pattern groups differed significantly between the two samples, suggesting variation in culturable bacterial
flora. Partial 16S rRNA gene sequences were determined for representatives of the commonest protein-pattern groups. Most of
the sequences obtained were previously unknown, but relatively closely related to known sequences of organisms belonging to
the α, β or γ subclasses of the proteobacteria, the first two subclasses being predominant. This classification of bacteria
isolated on a diluted nutrient-rich medium differed from recent culture-dependent studies using nutrient-rich media. The uncultivated
bacterial community was studied by analyzing ten partial 16S rRNA gene sequences cloned directly from activated sludge. None
of the cloned sequences was identical to those determined for culturable organisms; or to those in the GenBank database. They
were, however, related to the α or β subclasses of the proteobacteria, or to the gram-positive bacteria with a high G+C DNA
content.
Received: 4 November 1996 / Received revision: 24 February 1997 / Accepted: 28 February 1997 相似文献
17.
Abstract
The species composition of ammonia-oxidizing bacteria in aquatic environments was investigated using PCR primers for 16S rRNA
genes to amplify specific subsets of the total ammonia-oxidizer population. The specificity of the amplification reactions
was determined using total genomic DNA from known nitrifying strains and non-nitrifying strains identified as having similar
rDNA sequences. Specificity of amplification was determined both for direct amplification, using the nitrifier specific primers,
and with nested amplification, in which the nitrifier primers were used to reamplify a fragment obtained from direct amplification
with Eubacterial universal primers. The present level of specificity allows the distinction between Nitrosomonas europaea, Nitrosomonas sp. (marine) and the other known ammonia-oxidizers in the beta subclass of the Proteobacteria. Using total DNA extracted from natural samples, we used direct amplification to determine presence/absence of different species
groups. Species composition was found to differ among depths in vertical profiles of lake samples and among samples and enrichments
from various other aquatic environments. Nested PCR yielded several more positive reactions, which implies that nitrifier
DNA was present in most samples, but often at very low levels.
Received: 25 September 1995; Revised: 15 January 1996; Accepted: 20 February 1996 相似文献
18.
Abstract
Fluorescence-labeled antibodies and oligonucleotides were used simultaneously for the in situ identification of bacteria in
mixed cultures, as well as in the rhizosphere of inoculated plants. Counterstaining was performed with 4′-6-diamidino-2-phenylindole
(DAPI), and scanning confocal laser microscopy or epifluoresence microscopy with a charge-coupled device (CCD) camera were
used for detection of individual cells. This strategy gave insight into the relative abundance of an inoculated strain, enabled
the exact localization of single cells, and allowed the estimation of the metabolic activity of the bacteria in a complex
specimen. Using a strain-specific monoclonal antibody for Azospirillum brasilense Wa3, we could identify this particular strain in root samples of inoculated wheat plantlets. Strain Wa3, as well as other
bacteria colonizing the rhizosphere, were stained simultaneously with rRNA-targeted, fluorescence-labeled oligonucleotide
probes. In a co-inoculation experiment with A. brasilense strains Sp7 and Wa3, it was demonstrated by in situ identification and quantitative chemoluminescence ELISA that strain Sp7
outcompeted strain Wa3. The combined application of fluorescently labeled antibodies and oligonucleotides should be generally
applicable for monitoring specific bacterial strains, within the background of the same species, in relation to the total
microbiota.
Received: 18 March 1996; Accepted: 22 March 1996 相似文献
19.
Bhattacharya PR 《Current microbiology》2000,41(3):187-191
Hypertoxic mutant strains of Bacillus thuringiensis var. israelensis were isolated by mutagenesis of the parent strain. The correlation, if any, between hyper-production of insecticidal crystal
protein (δ-endotoxin) by hypertoxic mutant strains of Bacillus thuringiensis var. israelensis and sporulation-specific biochemical functions was studied. No increase in sporulation-specific biochemical markers was observed
in the hypertoxic mutant strains. Asporogenous mutants of hypertoxic mutant strains blocked at different stages of sporulation
were isolated, and larvicidal activity was studied. The hypertoxic parent strains and the sporulation-deficient, hypertoxic
mutant strains showed almost identical larvicidal activity. Therefore, the increased production of toxin is not related to
sporulation-specific biochemical changes.
Received: 14 February 2000 / Accepted: 21 March 2000 相似文献
20.
M. K. Sharma A. K. Goel L. Singh V. K. Rao 《World journal of microbiology & biotechnology》2006,22(11):1155-1159
Environmental surveillance for the presence of Vibrio cholerae O1 is of utmost importance for the effective public health protection of cholera. In the present study, an amperometric immunosensor was developed for detection of Vibrio cholerae in environmental samples by using disposable screen-printed electrodes (SPEs). For this purpose, the experiments done include fabrication of SPEs by using carbon ink, electrochemical characterization of electrodes, optimization of dilutions of antibodies and immobilization of antibody. V. cholerae O1 bacteria were spiked in various environmental water samples in known number. The seeded samples were filtered through a 0.22 μm membrane, and the filters enriched in alkaline peptone water for 6 h and then used directly for detection of V. cholerae using the immunosensor. The immunosensor could detect as few as 8 c.f.u./ml in hand-pump water (ground water) and seawater, and 80 c.f.u./ml in sewer water and tap water. The total time taken in this detection assay was 55 min. Thus, the proposed method is simple and can be used for environmental monitoring of V.␣cholerae. 相似文献