bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biotransformation and Bioconcentration of Steroid Estrogens by
Chlorella vulgaris
Authors: Lai K. M. , Scrimshaw M. D. , Lester J. N. 
Published: February 2003

ABSTRACT

The biotransformation and bioconcentration of natural and synthetic steroid estrogens by
Chlorella vulgaris
were investigated by using batch-shaking experiments with incubation for 48 h in the light or dark. Estradiol and estrone were interconvertible in both light and dark conditions; however, this biotransformation showed a preference for estrone. In the light, 50% estradiol was further metabolized to an unknown product. Apart from biotransformation, estrone, as well as hydroxyestrone, estriol, and ethinylestradiol, was relatively stable in the algal culture, whereas estradiol valerate was hydrolyzed to estradiol and then to estrone within 3 h of incubation. All of the tested estrogens exhibited a degree of partitioning to
C. vulgaris
; however, the concentrations of estriol, hydroxyestrone, ethinylestradiol, and estradiol valerate were always below the quantification limits. For estradiol and estrone, the partitioning of these estrogens in the algal extracts to the filtrates was <6% of the total amount present. The average concentration factor for estrone was ca. 27; however, the concentration factor for estradiol was not reported since no equilibrium was reached between the aqueous solution and that within the cells due to continuing biotransformation.
Highly Different Levels of Natural Transformation Are Associated with Genomic Subgroups within a Local Population of
Pseudomonas stutzeri
from Soil
Authors: Sikorski Johannes , Teschner Nicole , Wackernagel Wilfried 
Published: February 2003

ABSTRACT

A highly sensitive and specific PCR-based method of monitoring 16S rRNA genes of
Pseudomonas stutzeri
was developed for searching
P. stutzeri
DNA in environmental samples. This monitoring was combined with a reliable and sensitive method for isolating
P. stutzeri
colony formers from soil and sediment, depending on their utilization of ethylene glycol, starch, and maltose. With these techniques,
P. stutzeri
populations (
n
= 2 to 170) were obtained from five of six sites giving positive PCR signals (including three marine sediment and two soil samples). The phylogenetic positions of isolates from the five sites, based on their 16S ribosomal DNA sequences, indicated that the environmental isolates were affiliated with different genomovars of
P. stutzeri
. Using the broad-host-range plasmid pNS1 with kanamycin and gentamicin resistance determinants as the transforming DNA, naturally transformable strains were identified among the isolates from all sites. For one population from soil, the genetic relationship of the 120 members was determined by randomly amplified polymorphic DNA-PCR with three PCR primers. Among the population members which are taxonomically closely related as determined by 16S sequence comparisons of group representatives, a rather high genetic diversity and a characteristic clustering into subgroups were found. Remarkably, within the population, nontransformability and different levels of transformability (a frequency between about 10
−9
and 10
−4
per cell) were often associated with distinct genetic subgroups. It is concluded that transformability is widespread among environmental
P. stutzeri
strains and that its specific level is a heritable trait that may vary strongly within a local population.
Enzymatic Manganese(II) Oxidation by Metabolically Dormant Spores of Diverse
Bacillus
Species
Authors: Francis Chris A. , Tebo Bradley M. 
Published: February 2003

ABSTRACT

Bacterial spores are renowned for their longevity, ubiquity, and resistance to environmental insults, but virtually nothing is known regarding whether these metabolically dormant structures impact their surrounding chemical environments. In the present study, a number of spore-forming bacteria that produce dormant spores which enzymatically oxidize soluble Mn(II) to insoluble Mn(IV) oxides were isolated from coastal marine sediments. The highly charged and reactive surfaces of biogenic metal oxides dramatically influence the oxidation and sorption of both trace metals and organics in the environment. Prior to this study, the only known Mn(II)-oxidizing sporeformer was the marine
Bacillus
sp. strain SG-1, an extensively studied bacterium in which Mn(II) oxidation is believed to be catalyzed by a multicopper oxidase, MnxG. Phylogenetic analysis based on 16S rRNA and
mnxG
sequences obtained from 15 different Mn(II)-oxidizing sporeformers (including SG-1) revealed extensive diversity within the genus
Bacillus
, with organisms falling into several distinct clusters and lineages. In addition, active Mn(II)-oxidizing proteins of various sizes, as observed in sodium dodecyl sulfate-polyacrylamide electrophoresis gels, were recovered from the outer layers of purified dormant spores of the isolates. These are the first active Mn(II)-oxidizing enzymes identified in spores or gram-positive bacteria. Although extremely resistant to denaturation, the activities of these enzymes were inhibited by azide and
o
-phenanthroline, consistent with the involvement of multicopper oxidases. Overall, these studies suggest that the commonly held view that bacterial spores are merely inactive structures in the environment should be revised.
Transcriptional and Proteomic Analysis of a Ferric Uptake Regulator (Fur) Mutant of
Shewanella oneidensis
: Possible Involvement of Fur in Energy Metabolism, Transcriptional Regulation, and Oxidative Stress
Authors: Thompson Dorothea K. , Beliaev Alexander S. , Giometti Carol S. , Tollaksen Sandra L. , Khare Tripti , Lies Douglas P. , Nealson Kenneth H. , Lim Hanjo , Yates John , Brandt Craig C. , Tiedje James M. , Zhou Jizhong 
Published: February 2003

ABSTRACT

The iron-directed, coordinate regulation of genes depends on the
fur
(ferric uptake regulator) gene product, which acts as an iron-responsive, transcriptional repressor protein. To investigate the biological function of a
fur
homolog in the dissimilatory metal-reducing bacterium
Shewanella oneidensis
MR-1, a
fur
knockout strain (FUR1) was generated by suicide plasmid integration into this gene and characterized using phenotype assays, DNA microarrays containing 691 arrayed genes, and two-dimensional polyacrylamide gel electrophoresis. Physiological studies indicated that FUR1 was similar to the wild-type strain when they were compared for anaerobic growth and reduction of various electron acceptors. Transcription profiling, however, revealed that genes with predicted functions in electron transport, energy metabolism, transcriptional regulation, and oxidative stress protection were either repressed (
ccoNQ
,
etrA
, cytochrome
b
and
c
maturation-encoding genes,
qor
,
yiaY
,
sodB
,
rpoH
,
phoB
, and
chvI
) or induced (
yggW
,
pdhC
,
prpC
,
aceE
,
fdhD
, and
ppc
) in the
fur
mutant. Disruption of
fur
also resulted in derepression of genes (
hxuC
,
alcC
,
fhuA
,
hemR
,
irgA
, and
ompW
) putatively involved in iron uptake. This agreed with the finding that the
fur
mutant produced threefold-higher levels of siderophore than the wild-type strain under conditions of sufficient iron. Analysis of a subset of the FUR1 proteome (i.e., primarily soluble cytoplasmic and periplasmic proteins) indicated that 11 major protein species reproducibly showed significant (
P
< 0.05) differences in abundance relative to the wild type. Protein identification using mass spectrometry indicated that the expression of two of these proteins (SodB and AlcC) correlated with the microarray data. These results suggest a possible regulatory role of
S. oneidensis
MR-1 Fur in energy metabolism that extends the traditional model of Fur as a negative regulator of iron acquisition systems.
Characterization and Description of
Anaeromyxobacter dehalogenans
gen. nov., sp. nov., an Aryl-Halorespiring Facultative Anaerobic Myxobacterium
Authors: Sanford Robert A. , Cole James R. , Tiedje James M. 
Published: February 2003

ABSTRACT

Five strains were isolated which form a physiologically and phylogenetically coherent group of chlororespiring microorganisms and represent the first taxon in the
Myxobacteria
capable of anaerobic growth. The strains were enriched and isolated from various soils and sediments based on their ability to grow using acetate as an electron donor and 2-chlorophenol (2-CPh) as an electron acceptor. They are slender gram-negative rods with a bright red pigmentation that exhibit gliding motility and form spore-like structures. These unique chlororespiring myxobacteria also grow with 2,6-dichlorophenol, 2,5-dichlorophenol, 2-bromophenol, nitrate, fumarate, and oxygen as terminal electron acceptors, with optimal growth occurring at low concentrations (<1 mM) of electron acceptor. 2-CPh is reduced by all strains as an electron acceptor in preference to nitrate, which is reduced to ammonium. Acetate, H
2
, succinate, pyruvate, formate, and lactate were used as electron donors. None of the strains grew by fermentation. The 16S ribosomal DNA (rDNA) sequences of the five strains form a coherent cluster deeply branching within the family
Myxococcaceae
within the class
Myxobacteria
and are mostly closely associated with the
Myxococcus
subgroup. With the exception of anaerobic growth and lack of a characteristic fruiting body, these strains closely resemble previously characterized myxobacteria and therefore should be considered part of the
Myxococcus
subgroup. The anaerobic growth and 9.0% difference in 16S rDNA sequence from those of other myxobacterial genera are sufficient to place these strains in a new genus and species designated
Anaeromyxobacter dehalogenans
. The type strain is 2CP-1 (ATCC BAA-258).
Assessment of Fluorochromes for Two-Photon Laser Scanning Microscopy of Biofilms
Authors: Neu Thomas R. , Kuhlicke Ute , Lawrence John R. 
Published: February 2003

ABSTRACTA major limitation for the use of two-proton laser scanning microscopy (2P-LSM) in biofilm and other studies is the lack of a thorough understanding of the excitation-emission responses of potential fluorochromes. In order to use 2P-LSM, the utility of various fluorochromes and probes specific for a range of biofilm constituents must be evaluated. The fluorochromes tested in this study included classical nucleic acid-specific stains, such as acridine orange (AO) and 4",6"-diamidino-2-phenylindole (DAPI), as well as recently developed stains. In addition, stains specific for biofilm extracellular polymeric substances (EPS matrix components) were tested. Two-photon excitation with a Ti/Sapphire laser was carried out at wavelengths from 760 to 900 nm in 10-nm steps. It was found that autofluorescence of phototrophic organisms (cyanobacteria and green algae) resulted in strong signals for the entire excitation range. In addition, the coenzyme F420-related autofluorescence of methanogenic bacteria could be used to obtain images of dense aggregates (excitation wavelength, 780 nm). The intensities of the emission signals for the nucleic acid-specific fluorochromes varied. For example, the intensities were similar for excitation wavelengths ranging from 780 to 900 nm for AO but were higher for a narrower range, 780 to 810 nm, for DAPI. In selective excitation, fading, multiple staining, and combined single-photon-two-photon studies, the recently developed nucleic acid-specific fluorochromes proved to be more suitable regardless of whether they are intended for living or fixed samples. Probes specific for proteins and glycoconjugates allowed two-photon imaging of polymeric biofilm constituents. Selective excitation-emission was observed for Calcofluor White M2R (780 to 800 nm) and SyproOrange (880 to 900 nm). In addition, fluor-conjugated concanavalin A lectins were examined and provided acceptable two-photon emission signals at wavelengths ranging from 780 to 800 nm. Finally, CellTracker, a fluorochrome suitable for long-term labeling of microbial eucaryote cells, was found to give strong emission at wavelengths ranging from 770 to 810 nm. If fluorochromes have the same two-photon excitation cross section, they are suitable for multiple staining and multichannel recording. Generally, if an appropriate excitation wavelength and fluorochrome were used, it was possible to obtain more highly resolved images for thick biofilm samples with two-photon laser microscopy than with conventional single-photon laser microscopy. Due to its potential for higher resolution in light-scattering tissue-like material, such as biofilms, and extremely localized excitation, 2P-LSM is a valuable addition to conventional confocal laser scanning microscopy with single-photon excitation. However, further development of the method and basic research are necessary to take full advantage of nonlinear excitation in studies of interfacial microbial ecology.
Production and Targeting of theBrucella abortusAntigen L7/L12 inLactococcus lactis: a First Step towards Food-Grade Live Vaccines against Brucellosis
Authors: Ribeiro Luciana A. , Azevedo Vasco , Le Loir Yves , Oliveira Sergio C. , Dieye Yakhya , Piard Jean-Christophe , Gruss Alexandra , Langella Philippe 
Published: February 2003

ABSTRACTBrucella abortusis a facultative intracellular gram-negative bacterial pathogen that infects humans and animals by entry mainly through the digestive tract.B. abortuscauses abortion in pregnant cattle and undulant fever in humans. The immunogenicB. abortusribosomal protein L7/L12 is a promising candidate antigen for the development of oral live vaccines against brucellosis, using food-grade lactic acid bacteria (LAB) as a carrier. TheL7/L12gene was expressed inLactococcus lactis, the model LAB, under the nisin-inducible promoter. Using different signals, L7/L12 was produced in cytoplasmic, cell-wall-anchored, and secreted forms. Cytoplasmic production of L7/L12 gave a low yield, estimated at 0.5 mg/liter. Interestingly, a secretable form of this normally cytoplasmic protein via fusion with a signal peptide resulted in increased yield of L7/L12 to 3 mg/liter; secretion efficiency (SE) was 35%. A fusion between the mature moiety of the staphylococcal nuclease (Nuc) and L7/L12 further increased yield to 8 mg/liter. Fusion with a synthetic propeptide (LEISSTCDA) previously described as an enhancer for heterologous protein secretion inL. lactis(Y. Le Loir, A. Gruss, S. D. Ehrlich, and P. Langella, J. Bacteriol. 180:1895-1903, 1998) raised the yield to 8 mg/liter and SE to 50%. A surface-anchored L7/L12 form inL. lactiswas obtained by fusing the cell wall anchor ofStreptococcus pyogenesM6 protein to the C-terminal end of L7/L12. The fusions described allow the production and targeting of L7/L12 in three different locations inL. lactis. This is the first example of aB. abortusantigen produced in a food-grade bacterium and opens new perspectives for alternative vaccine strategies against brucellosis.
Production of Human Papillomavirus Type 16 E7 Protein in
Lactococcus lactis
Authors: Bermúdez-Humarán L. G. , Langella P. , Miyoshi A. , Gruss A. , Guerra R. Tamez , Montes de Oca-Luna R. , Le Loir Y. 
Published: February 2003

ABSTRACT

The E7 protein of human papillomavirus type 16 was produced in
Lactococcus lactis.
Secretion allowed higher production yields than cytoplasmic production. In stationary phase, amounts of cytoplasmic E7 were reduced, while amounts of secreted E7 increased, suggesting a phase-dependent intracellular proteolysis. Fusion of E7 to the staphylococcal nuclease, a stable protein, resulted in a highly stable cytoplasmic protein. This work provides new candidates for development of viral screening systems and for oral vaccine against cervical cancer.
Heavy Metal Resistance Patterns of
Frankia
Strains
Authors: Richards Joel W. , Krumholz Glenn D. , Chval Matthew S. , Tisa Louis S. 
Published: February 2003

ABSTRACT

The sensitivity of 12
Frankia
strains to heavy metals was determined by a growth inhibition assay. In general, all of the strains were sensitive to low concentrations (<0.5 mM) of Ag
1+
, AsO
2
1−
, Cd
2+
, SbO
2
1−
, and Ni
2+
, but most of the strains were less sensitive to Pb
2+
(6 to 8 mM), CrO
4
2−
(1.0 to 1.75 mM), AsO
4
3−
(>50 mM), and SeO
2
2−
(1.5 to 3.5 mM). While most strains were sensitive to 0.1 mM Cu
2+
, four strains were resistant to elevated levels of Cu
2+
(2 to 5 mM and concentrations as high as 20 mM). The mechanism of SeO
2
2−
resistance seems to involve reduction of the selenite oxyanion to insoluble elemental selenium, whereas Pb
2+
resistance and Cu
2+
resistance may involve sequestration or binding mechanisms. Indications of the resistance mechanisms for the other heavy metals were not as clear.
Natural Communities of Novel Archaea and Bacteria with a String-of-Pearls-Like Morphology: Molecular Analysis of the Bacterial Partners
Authors: Moissl Christine , Rudolph Christian , Huber Robert 
Published: February 2003

ABSTRACT

A recently discovered bacterial/archaeal association, growing in a string-of-pearls-like structure, thrives in the cold (∼10°C) sulfidic marsh water of the Sippenauer Moor near Regensburg, Bavaria, Germany. It forms characteristic, macroscopically visible globules, the pearls, containing microcolonies of novel euryarchaeota, which are surrounded by mainly filamentous bacteria (C. Rudolph, G. Wanner, and R. Huber, Appl. Environ. Microbiol. 67:2336-2344, 2001). Single pearls in series are connected by white threads. Here we report the first detailed molecular investigations of the taxonomic affiliation of the bacteria contributing to the strings of pearls. Phylogenetic analysis showed the dominance of a single phylotype (clone sipK4) within single pearls most closely related to
Thiothrix unzii
. The presence of
Thiothrix
sipK4 as a major constituent of single pearls and of the pearl-connecting white threads was verified by fluorescence in situ hybridization.
Streptococcus thermophilus
Is Able To Produce a β-Galactosidase Active during Its Transit in the Digestive Tract of Germ-Free Mice
Authors: Drouault Sophie , Anba Jamila , Corthier Gérard 
Published: February 2003

ABSTRACT

This work presents data on the application of a bacterial luciferase used to monitor gene expression of
Streptococcus thermophilus
in the digestive tract. The main result is that the bacterium was able to produce an active β-galactosidase in the digestive tract, although it did not multiply during its transit. This production was enhanced when lactose (the inducer) was added to the diet.
Genetic and Immunochemical Characterization of Thiocyanate-Degrading Bacteria in Lake Water
Authors: Yamasaki Manabu , Matsushita Yasuhiko , Namura Motonobu , Nyunoya Hiroshi , Katayama Yoko 
Published: February 2003

ABSTRACT

Natural aquatic and soil samples were screened for the presence of thiocyanate-degrading bacteria. Using thiocyanate supplementation, we established an enrichment culture containing such bacteria from lake water. The dominant bacteria had the
scnC-LS5
gene encoding thiocyanate hydrolase, which was closely related to the enzyme found previously in
Thiobacillus thioparus
THI115 isolated from activated sludge.
Two Forms of NAD-Dependent
d
-Mandelate Dehydrogenase in
Enterococcus faecalis
IAM 10071
Authors: Tamura Yusuke , Ohkubo Atsuko , Iwai Saho , Wada Yoichiro , Shinoda Takeshi , Arai Kazuhito , Mineki Shigeru , Iida Mitsugi , Taguchi Hayao 
Published: February 2003

ABSTRACT

Two forms of NAD-dependent
d
-mandelate dehydrogenase (
d
-ManDHs) were purified from
Enterococcus faecalis
IAM 10071. While these two enzymes consistently exhibited high activity toward large 2-ketoacid substrates that were branched at the C3 or C4 position, they gave distinctly different

K
m

and
V
max
values for these substrates and had distinct molecular weights by gel electrophoresis and gel filtration.
Rapid Two-Step Procedure for Large-Scale Purification of Pediocin-Like Bacteriocins and Other Cationic Antimicrobial Peptides from Complex Culture Medium
Authors: Uteng Marianne , Hauge Håvard Hildeng , Brondz Ilia , Nissen-Meyer Jon , Fimland Gunnar 
Published: February 2003

ABSTRACT
A rapid and simple two-step procedure suitable for both small- and large-scale purification of pediocin-like bacteriocins and other cationic peptides has been developed. In the first step, the bacterial culture was applied directly on a cation-exchange column (1-ml cation exchanger per 100-ml cell culture). Bacteria and anionic compounds passed through the column, and cationic bacteriocins were subsequently eluted with 1 M NaCl. In the second step, the bacteriocin fraction was applied on a low-pressure, reverse-phase column and the bacteriocins were detected as major optical density peaks upon elution with propanol. More than 80% of the activity that was initially in the culture supernatant was recovered in both purification steps, and the final bacteriocin preparation was more than 90% pure as judged by analytical reverse-phase chromatography and capillary electrophoresis.
Coexistence of Two Distinct Copies of Naphthalene Degradation Genes in
Pseudomonas
Strains Isolated from the Western Mediterranean Region
Authors: Ferrero Marcela , Llobet-Brossa Enrique , Lalucat Jorge , García-Valdés Elena , Rosselló-Mora Ramón , Bosch Rafael 
Published: February 2003

ABSTRACT

We analyzed the occurrence of the naphthalene degradation upper-pathway (
nah
) genes in the western Mediterranean region. The amplification, restriction, and sequence analysis of internal fragments for several
nah
genes (
nahAc
,
nahB
,
nahC
, and
nahE
) from naphthalene-degrading strains isolated from this geographical area proved the coexistence of two distinct sets of
nah
genes.
Microbial Growth Inside Insulated External Walls as an Indoor Air Biocontamination Source
Authors: Pessi Anna-Mari , Suonketo Jommi , Pentti Matti , Kurkilahti Mika , Peltola Kaija , Rantio-Lehtimäki Auli 
Published: February 2003

ABSTRACT
The association between moisture-related microbial growth (mesophilic fungi and bacteria) within insulated exterior walls and microbial concentrations in the indoor air was studied. The studied apartment buildings with precast concrete external walls were situated in a subarctic zone. Actinomycetes in the insulation layer were found to have increased concentrations in the indoor air. The moisture content of the indoor air significantly affected all measurable airborne concentrations.
Chemotaxis of
Ralstonia eutropha
JMP134(pJP4) to the Herbicide 2,4-Dichlorophenoxyacetate
Authors: Hawkins Andrew C. , Harwood Caroline S. 
Published: February 2003

ABSTRACT

Ralstonia eutropha
JMP134(pJP4) and several other species of motile bacteria can degrade the herbicide 2,4-dichlorophenoxyacetate (2,4-D), but it was not known if bacteria could sense and swim towards 2,4-D by the process of chemotaxis. Wild-type
R. eutropha
cells were chemotactically attracted to 2,4-D in swarm plate assays and qualitative capillary assays. The chemotactic response was induced by growth with 2,4-D and depended on the presence of the catabolic plasmid pJP4, which harbors the
tfd
genes for 2,4-D degradation. The
tfd
cluster also encodes a permease for 2,4-D named TfdK. A
tfdK
mutant was not chemotactic to 2,4-D, even though it grew at wild-type rates on 2,4-D.
Isolation and Characterization of Bacteriophages from Fermenting Sauerkraut
Authors: Yoon S. S. , Barrangou-Poueys R. , Breidt F. , Klaenhammer T. R. , Fleming H. P. 
Published: February 2003

ABSTRACT

This paper presents the first report of bacteriophage isolated from commercial vegetable fermentations. Nine phages were isolated from two 90-ton commercial sauerkraut fermentations. These phages were active against fermentation isolates and selected
Leuconostoc mesenteroides
and
Lactobacillus plantarum
strains, including a starter culture. Phages were characterized as members of the
Siphoviridae
and
Myoviridae
families. All
Leuconostoc
phages reported previously, primarily of dairy origin, belonged to the
Siphoviridae
family.