bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cometabolic Degradation of Dibenzofuran by Biphenyl-Cultivated
Ralstonia
sp. Strain SBUG 290
Authors: Becher Dörte , Specht Michael , Hammer Elke , Francke Wittko , Schauer Frieder 
Published: July 2002

ABSTRACT

Cells of the gram-negative bacterium
Ralstonia
sp. strain SBUG 290 grown in the presence of biphenyl are able to cooxidize dibenzofuran which has been 1,2-hydroxylated. Meta cleavage of the 1,2-dihydroxydibenzofuran between carbon atoms 1 and 9b produced 2-hydroxy-4-(3′-oxo-3′
H
-benzofuran-2′-yliden)but-2-enoic acid, which was degraded completely via salicylic acid. The presence of these intermediates indicates a degradation mechanism for dibenzofuran via lateral dioxygenation by
Ralstonia
sp. strain SBUG 290.
Transition from Anaerobic to Aerobic Growth Conditions for the Sulfate-Reducing Bacterium
Desulfovibrio oxyclinae
Results in Flocculation
Authors: Sigalevich Pavel , Meshorer Eran , Helman Yael , Cohen Yehuda 
Published: July 2002

ABSTRACT

A chemostat culture of the sulfate-reducing bacterium
Desulfovibrio oxyclinae
isolated from the oxic layer of a hypersaline cyanobacterial mat was grown anaerobically and then subjected to gassing with 1% oxygen, both at a dilution rate of 0.05 h
−1
. The sulfate reduction rate under anaerobic conditions was 370 nmol of SO
4
2−
mg of protein
−1
min
−1
. At the onset of aerobic gassing, sulfate reduction decreased by 40%, although viable cell numbers did not decrease. After 42 h, the sulfate reduction rate returned to the level observed in the anaerobic culture. At this stage the growth yield increased by 180% compared to the anaerobic culture to 4.4 g of protein per mol of sulfate reduced. Protein content per cell increased at the same time by 40%. The oxygen consumption rate per milligram of protein measured in washed cell suspensions increased by 80%, and the thiosulfate reduction rate of the same samples increased by 29% with lactate as the electron donor. These findings indicated possible oxygen-dependent enhancement of growth. After 140 h of growth under oxygen flux, formation of cell aggregates 0.1 to 3 mm in diameter was observed. Micrometer-sized aggregates were found to form earlier, during the first hours of exposure to oxygen. The respiration rate of
D. oxyclinae
was sufficient to create anoxia inside clumps larger than 3 μm, while the levels of dissolved oxygen in the growth vessel were 0.7 ± 0.5 μM. Aggregation of sulfate-reducing bacteria was observed within a
Microcoleus chthonoplastes
-dominated layer of a cyanobacterial mat under daily exposure to oxygen concentrations of up to 900 μM.
Desulfonema
-like sulfate-reducing bacteria were also common in this environment along with other nonaggregated sulfate-reducing bacteria. Two-dimensional mapping of sulfate reduction showed heterogeneity of sulfate reduction activity in this oxic zone.
Rapid Detection and Quantification of Members of the Archaeal Community by Quantitative PCR Using Fluorogenic Probes
Authors: Takai Ken , Horikoshi Koki 
Published: July 2002

ABSTRACT
We describe a rapid, reproducible, and sensitive method for detection and quantification of archaea in naturally occurring microbial communities. A domain-specific PCR primer set and a domain-specific fluorogenic probe having strong and weak selectivity, respectively, for archaeal rRNA genes (rDNAs) were designed. A universal PCR primer set and a universal fluorogenic probe for both bacterial and archaeal rDNAs were also designed. Using these primers and probes, we demonstrated that detection and quantification of archaeal rDNAs in controlled microbial rDNA assemblages can be successfully achieved. The system which we designed was also able to detect and quantify archaeal rDNAs in DNA samples obtained not only from environments in which thermophilic archaea are abundant but also from environments in which methanogenic archaea are abundant. Our findings indicate that this method is applicable to culture-independent molecular analysis of microbial communities in various environments.
Nutritional Requirements and Nitrogen-Dependent Regulation of Proteinase Activity of
Lactobacillus helveticus
CRL 1062
Authors: Hebert Elvira M. , Raya Raul R. , De Giori Graciela S. 
Published: July 2002

ABSTRACT

The nutritional requirements of
Lactobacillus helveticus
CRL 1062 were determined with a simplified chemically defined medium (SCDM) and compared with those of
L. helveticus
CRL 974 (ATCC 15009). Both strains were found to be prototrophic for alanine, glycine, asparagine, glutamine, and cysteine. In addition, CRL 1062 also showed prototrophy for lysine and serine. The microorganisms also required riboflavin, calcium pantothenate, pyridoxal, nicotinic acid, and uracil for growth in liquid SCDM. The growth rate and the synthesis of their cell membrane-bound serine proteinases, but not of their intracellular leucyl-aminopeptidases, were influenced by the peptide content of the medium. The highest proteinase levels were found during cell growth in basal SCDM, while the synthesis of this enzyme was inhibited in SCDM supplemented with Casitone, Casamino Acids, or β-casein. Low-molecular-mass peptides (<3,000 Da), extracted from Casitone, and the dipeptide leucylproline (final concentration, 5 mM) play important roles in the medium-dependent regulation of proteinase activity. The addition of the dipeptide leucylproline (5 mM) to SCDM reduced proteinase activity by 25%.
Bacterial Activity in the Rhizosphere Analyzed at the Single-Cell Level by Monitoring Ribosome Contents and Synthesis Rates
Authors: Ramos Cayo , Mølbak Lars , Molin Søren 
Published: July 2002

ABSTRACT

The growth activity of
Pseudomonas putida
cells colonizing the rhizosphere of barley seedlings was estimated at the single-cell level by monitoring ribosomal contents and synthesis rates. Ribosomal synthesis was monitored by using a system comprising a fusion of the ribosomal
Escherichia coli rrnB
P1 promoter to a gene encoding an unstable variant of the green fluorescent protein (Gfp). Gfp expression in a
P. putida
strain carrying this system inserted into the chromosome was strongly dependent on the growth phase and growth rate of the strain, and cells growing exponentially at rates of ≥0.17 h
−1
emitted growth rate-dependent green fluorescence detectable at the single-cell level. The single-cell ribosomal contents were very heterogeneous, as determined by quantitative hybridization with fluorescently labeled rRNA probes in
P. putida
cells extracted from the rhizosphere of 1-day-old barley seedlings grown under sterile conditions. After this, cells extracted from the root system had ribosomal contents similar to those found in starved cells. There was a significant decrease in the ribosomal content of
P. putida
cells when bacteria were introduced into nonsterile bulk or rhizosphere soil, and the Gfp monitoring system was not induced in cells extracted from either of the two soil systems. The monitoring system used permitted nondestructive in situ detection of fast-growing bacterial microcolonies on the sloughing root sheath cells of 1- and 2-day-old barley seedlings grown under sterile conditions, which demonstrated that it may be possible to use the unstable Gfp marker for studies of transient gene expression in plant-microbe systems.
Distribution of
Nitrosomonas europaea
and
Paracoccus denitrificans
Immobilized in Tubular Polymeric Gel for Nitrogen Removal
Authors: Uemoto Hiroaki , Saiki Hiroshi 
Published: July 2002

ABSTRACT

To improve the cooperative removal of nitrogen by
Nitrosomonas europaea
and
Paracoccus denitrificans
, we controlled their distribution in a tubular gel. When ethanol was supplied inside the tubular gel as an electron donor, their distributions overlapped in the external region of the gel. By changing the electron donor from ethanol to gaseous hydrogen, the distribution of
P. denitrificans
shifted to the inside of the tube and was separated from that of
N. europaea
. The separation resulted in an increase of the oxidation rate of ammonia by 25%.
Cloning and Sequencing of an Alkaline Protease Gene from
Bacillus lentus
and Amplification of the Gene on the
B. lentus
Chromosome by an Improved Technique
Authors: Jørgensen Per Linå , Tangney Martin , Pedersen Poul Erik , Hastrup Sven , Diderichsen Børge , Jørgensen Steen T. 
Published: July 2002

ABSTRACT
A gene encoding an alkaline protease was cloned from an alkalophilic bacillus, and its nucleotide sequence was determined. The cloned gene was used to increase the copy number of the protease gene on the chromosome by an improved gene amplification technique.
Atypical Polyphosphate Accumulation by the Denitrifying Bacterium
Paracoccus denitrificans
Authors: Barak Yoram , van Rijn Jaap 
Published: July 2002

ABSTRACT

Polyphosphate accumulation by
Paracoccus denitrificans
was examined under aerobic, anoxic, and anaerobic conditions. Polyphosphate synthesis by this denitrifier took place with either oxygen or nitrate as the electron acceptor and in the presence of an external carbon source. Cells were capable of poly-β-hydroxybutyrate (PHB) synthesis, but no polyphosphate was produced when PHB-rich cells were incubated under anoxic conditions in the absence of an external carbon source. By comparison of these findings to those with polyphosphate-accumulating organisms thought to be responsible for phosphate removal in activated sludge systems, it is concluded that
P. denitrificans
is capable of combined phosphate and nitrate removal without the need for alternating anaerobic/aerobic or anaerobic/anoxic switches. Studies on additional denitrifying isolates from a denitrifying fluidized bed reactor suggested that polyphosphate accumulation is widespread among denitrifiers.
Involvement of Acyl Coenzyme A Oxidase Isozymes in Biotransformation of Methyl Ricinoleate into γ-Decalactone by
Yarrowia lipolytica
Authors: Waché Yves , Laroche Céline , Bergmark Karin , Møller-Andersen Charlotte , Aguedo Mario , Le Dall Marie-Thérèse , Wang Huijie , Nicaud Jean-Marc , Belin Jean-Marc 
Published: July 2002

ABSTRACT

We reported previously on the function of acyl coenzyme A (acyl-CoA) oxidase isozymes in the yeast
Yarrowia lipolytica
by investigating strains disrupted in one or several acyl-CoA oxidase-encoding genes (
POX1
through
POX5
) (H. Wang et al., J. Bacteriol. 181:5140–5148, 1999). Here, these mutants were studied for lactone production. Monodisrupted strains produced similar levels of lactone as the wild-type strain (50 mg/liter) except for Δ
pox3
, which produced 220 mg of γ-decalactone per liter after 24 h. The Δ
pox2 Δpox3
double-disrupted strain, although slightly affected in growth, produced about 150 mg of lactone per liter, indicating that Aox2p was not essential for the biotransformation. The Δ
pox2 Δpox3 Δpox5
triple-disrupted strain produced and consumed lactone very slowly. On the contrary, the Δ
pox2 Δpox3 Δpox4 Δpox5
multidisrupted strain did not grow or biotransform methyl ricinoleate into γ-decalactone, demonstrating that Aox4p is essential for the biotransformation.
Influence of
Acanthamoeba castellanii
on Intracellular Growth of Different
Legionella
Species in Human Monocytes
Authors: Neumeister B. , Reiff G. , Faigle M. , Dietz K. , Northoff H. , Lang F. 
Published: July 2002

ABSTRACT

Previous studies using a murine model of coinhalation of
Legionella pneumophila
and
Hartmannella vermiformis
have shown a significantly enhanced intrapulmonary growth of
L. pneumophila
in comparison to inhalation of legionellae alone (J. Brieland, M. McClain, L. Heath, C. Chrisp, G. Huffnagle, M. LeGendre, M. Hurley, J. Fantone, and C. Engleberg, Infect. Immun. 64:2449–2456, 1996). In this study, we introduce an in vitro coculture model of legionellae, Mono Mac 6 cells (MM6) and
Acanthamoeba castellanii
, using a cell culture chamber system which separates both cell types by a microporous polycarbonate membrane impervious to bacteria, amoebae, and human cells. Whereas
L. pneumophila
has shown a maximal 4-log-unit multiplication within MM6, which could not be further increased by coculture with
Acanthamoeba castellanii
, significantly enhanced replication of
L. gormanii
,
L. micdadei
,
L. steigerwaltii
,
L. longbeachae
, and
L. dumoffii
was seen after coculture with amoebae. This effect was seen only with uninfected amoebae, not with
Legionella
-infected amoebae. The supporting effect for intracellular multiplication in MM6 could be reproduced in part by addition of a cell-free coculture supernatant obtained from a coincubation experiment with uninfected
A. castellanii
and
Legionella
-infected MM6, suggesting that amoeba-derived effector molecules are involved in this phenomenon. This coculture model allows investigations of molecular and biochemical mechanisms which are responsible for the enhancement of intracellular multiplication of legionellae in monocytic cells after interaction with amoebae.
Natural Assemblages of Marine Proteobacteria and Members of the
Cytophaga-Flavobacter
Cluster Consuming Low- and High-Molecular-Weight Dissolved Organic Matter
Authors: Cottrell Matthew T. , Kirchman David L. 
Published: July 2002

ABSTRACT

We used a method that combines microautoradiography with hybridization of fluorescent rRNA-targeted oligonucleotide probes to whole cells (MICRO-FISH) to test the hypothesis that the relative contributions of various phylogenetic groups to the utilization of dissolved organic matter (DOM) depend solely on their relative abundance in the bacterial community. We found that utilization of even simple low-molecular-weight DOM components by bacteria differed across the major phylogenetic groups and often did not correlate with the relative abundance of these bacterial groups in estuarine and coastal environments. The
Cytophaga-Flavobacter
cluster was overrepresented in the portion of the assemblage consuming chitin,
N
-acetylglucosamine, and protein but was generally underrepresented in the assemblage consuming amino acids. The amino acid-consuming assemblage was usually dominated by the α subclass of the class
Proteobacteria
, although the representation of α-proteobacteria in the protein-consuming assemblages was about that expected from their relative abundance in the entire bacterial community. In our experiments, no phylogenetic group dominated the consumption of all DOM, suggesting that the participation of a diverse assemblage of bacteria is essential for the complete degradation of complex DOM in the oceans. These results also suggest that the role of aerobic heterotrophic bacteria in carbon cycling would be more accurately described by using three groups instead of the single bacterial compartment currently used in biogeochemical models.
Chlorine, Chloramine, Chlorine Dioxide, and Ozone Susceptibility of
Mycobacterium avium
Authors: Taylor Robert H. , Falkinham Joseph O. , Norton Cheryl D. , LeChevallier Mark W. 
Published: July 2002

ABSTRACT

Environmental and patient isolates of
Mycobacterium avium
were resistant to chlorine, monochloramine, chlorine dioxide, and ozone. For chlorine, the product of the disinfectant concentration (in parts per million) and the time (in minutes) to 99.9% inactivation for five
M. avium
strains ranged from 51 to 204. Chlorine susceptibility of cells was the same in washed cultures containing aggregates and in reduced aggregate fractions lacking aggregates. Cells of the more slowly growing strains were more resistant to chlorine than were cells of the more rapidly growing strains. Water-grown cells were 10-fold more resistant than medium-grown cells. Disinfectant resistance may be one factor promoting the persistence of
M. avium
in drinking water.
Anaerobic-Aerobic Process for Microbial Degradation of Tetrabromobisphenol A
Authors: Ronen Zeev , Abeliovich Aharon 
Published: July 2002

ABSTRACT
Tetrabromobisphenol A (TBBPA) is a flame retardant that is used as an additive during manufacturing of plastic polymers and electronic circuit boards. Little is known about the fate of this compound in the environment. In the current study we investigated biodegradation of TBBPA, as well as 2,4,6-tribromophenol (TBP), in slurry of anaerobic sediment from a wet ephemeral desert stream bed contaminated with chemical industry waste. Anaerobic incubation of the sediment with TBBPA and peptone-tryptone-glucose-yeast extract medium resulted in a 80% decrease in the TBBPA concentration and accumulation of a single metabolite. This metabolite was identified by gas chromatography-mass spectrometry (GC-MS) as nonbrominated bisphenol A (BPA). On the other hand, TBP was reductively dehalogenated to phenol, which was further metabolized under anaerobic conditions. BPA persisted in the anaerobic slurry but was degraded aerobically. A gram-negative bacterium (strain WH1) was isolated from the contaminated soil, and under aerobic conditions this organism could use BPA as a sole carbon and energy source. During degradation of BPA two metabolites were detected in the culture medium, and these metabolites were identified by GC-MS and high-performance liquid chromatography as 4-hydroxybenzoic acid and 4-hydroxyacetophenone. Both of those compounds were utilized by WH1 as carbon and energy sources. Our findings demonstrate that it may be possible to use a sequential anaerobic-aerobic process to completely degrade TBBPA in contaminated soils.
Comparative Survival Rates of Human-Derived Probiotic
Lactobacillus paracasei
and
L. salivarius
Strains during Heat Treatment and Spray Drying
Authors: Gardiner G. E. , O'Sullivan E. , Kelly J. , Auty M. A. E. , Fitzgerald G. F. , Collins J. K. , Ross R. P. , Stanton C. 
Published: July 2002

ABSTRACT

Spray drying of skim milk was evaluated as a means of preserving
Lactobacillus paracasei
NFBC 338 and
Lactobacillus salivarius
UCC 118, which are human-derived strains with probiotic potential. Our initial experiments revealed that NFBC 338 is considerably more heat resistant in 20% (wt/vol) skim milk than UCC 118 is; the comparable decimal reduction times were 11.1 and 1.1 min, respectively, at 59°C. An air outlet temperature of 80 to 85°C was optimal for spray drying; these conditions resulted in powders with moisture contents of 4.1 to 4.2% and viable counts of 3.2 × 10
9
CFU/g for NFBC 338 and 5.2 × 10
7
CFU/g for UCC 118. Thus,
L. paracasei
NFBC 338 survived better than
L. salivarius
UCC 118 during spray drying; similar results were obtained when we used confocal scanning laser microscopy and LIVE/DEAD
Bac
Light viability staining. In addition, confocal scanning laser microscopy revealed that the probiotic lactobacilli were located primarily in the powder particles. Although both spray-dried cultures appeared to be stressed, as shown by increased sensitivity to NaCl, bacteriocin production by UCC 118 was not affected by the process, nor was the activity of the bacteriocin peptide. The level of survival of NFBC 338 remained constant at ∼1 × 10
9
CFU/g during 2 months of powder storage at 4°C, while a decline in the level of survival of approximately 1 log (from 7.2 × 10
7
to 9.5 × 10
6
CFU/g) was observed for UCC 118 stored under the same conditions. However, survival of both
Lactobacillus
strains during powder storage was inversely related to the storage temperature. Our data demonstrate that spray drying may be a cost-effective way to produce large quantities of some probiotic cultures.
Methods for Intense Aeration, Growth, Storage, and Replication of Bacterial Strains in Microtiter Plates
Authors: Duetz Wouter A. , Rüedi Lorenz , Hermann Robert , O'Connor Kevin , Büchs Jochen , Witholt Bernard 
Published: July 2002

ABSTRACT

Miniaturized growth systems for heterogeneous culture collections are not only attractive in reducing demands for incubation space and medium but also in making the parallel handling of large numbers of strains more practicable. We report here on the optimization of oxygen transfer rates in deep-well microtiter plates and the development of a replication system allowing the simultaneous and reproducible sampling of 96 frozen glycerol stock cultures while the remaining culture volume remains frozen. Oxygen transfer rates were derived from growth curves of
Pseudomonas putida
and from rates of oxygen disappearance due to the cobalt-catalyzed oxidation of sulfite. Maximum oxygen transfer rates (38 mmol liter
−1
h
−1
, corresponding to a mass transfer coefficient of 188 h
−1
) were measured during orbital shaking at 300 rpm at a shaking diameter of 5 cm and a culture volume of 0.5 ml. A shaking diameter of 2.5 cm resulted in threefold-lower values. These high oxygen transfer rates allowed
P. putida
to reach a cell density of approximately 9 g (dry weight) liter
−1
during growth on a glucose mineral medium at culture volumes of up to 1 ml. The growth-and-replication system was evaluated for a culture collection consisting of aerobic strains, mainly from the genera
Pseudomonas
,
Rhodococcus
, and
Alcaligenes
, using mineral media and rich media. Cross-contamination and excessive evaporation during vigorous aeration were adequately prevented by the use of a sandwich cover of spongy silicone and cotton wool on top of the microtiter plates.
Relationship between Membrane Damage and Cell Death in Pressure-Treated
Escherichia coli
Cells: Differences between Exponential- and Stationary-Phase Cells and Variation among Strains
Authors: Pagán Rafael , Mackey Bernard 
Published: July 2002

ABSTRACT

The relationship between membrane damage and loss of viability following pressure treatment was examined in
Escherichia coli
strains C9490, H1071, and NCTC 8003. These strains showed high, medium, and low resistance to pressure, respectively, in stationary phase but similar resistance to pressure in exponential phase. Loss of membrane integrity was measured as loss of osmotic responsiveness or as increased uptake of the fluorescent dye propidium iodide. In exponential-phase cells, loss of viability was correlated with a permanent loss of membrane integrity in all strains, whereas in stationary-phase cells, a more complicated picture emerged in which cell membranes became leaky during pressure treatment but resealed to a greater or lesser extent following decompression. Strain H1071 displayed a very unusual pressure response in stationary phase in which survival decreased to a minimum at 300 MPa but then increased at 400 to 500 MPa before decreasing again. Membranes were unable to reseal after treatment at 300 MPa but could do so after treatment at higher pressures. Membrane damage in this strain was thus typical of exponential-phase cells under low-pressure conditions but of stationary-phase cells under higher-pressure conditions. Heat shock treatment of strain H1071 cells increased pressure resistance under low-pressure conditions and also allowed membrane damage to reseal. Growth in the presence of IPTG (isopropyl-β-
d
-thiogalactopyranoside) increased resistance under high-pressure conditions. The mechanisms of inactivation may thus differ at high and low pressures. These studies support the view that membrane damage is an important event in the inactivation of bacteria by high pressure, but the nature of membrane damage and its relation to cell death may differ between species and phases of growth.
Extremely Halophilic
Bacteria
in Crystallizer Ponds from Solar Salterns
Authors: Antón Josefa , Rosselló-Mora Ramón , Rodríguez-Valera Francisco , Amann Rudolf 
Published: July 2002

ABSTRACT

It is generally assumed that hypersaline environments with sodium chloride concentrations close to saturation are dominated by halophilic members of the domain
Archaea
, while
Bacteria
are not considered to be relevant in this kind of environment. Here, we report the high abundance and growth of a new group of hitherto-uncultured
Bacteria
in crystallizer ponds (salinity, from 30 to 37%) from multipond solar salterns. In the present study, these
Bacteria
constituted from 5 to 25% of the total prokaryotic community and were affiliated with the
Cytophaga-Flavobacterium-Bacteroides
phylum. Growth was demonstrated in saturated NaCl. A provisional classification of this new bacterial group as “
Candidatus
Salinibacter gen. nov.” is proposed. The perception that
Archaea
are the only ecologically relevant prokaryotes in hypersaline aquatic environments should be revised.