bluuebunny/crossref_metadata_2025_split huggingface dataset:
Monolayer Adsorption of a “Bald” Mutant of the Highly Adhesive and Hydrophobic Bacterium
Acinetobacter
sp. Strain Tol 5 to a Hydrocarbon Surface
Authors: Hori Katsutoshi , Watanabe Hisami , Ishii Shun'ichi , Tanji Yasunori , Unno Hajime 
Published: March 2008

ABSTRACT

The affinity of microbial cells for hydrophobic interfaces is important because it directly affects the efficiency of various bioprocesses, including green biotechnologies. The toluene-degrading bacterium
Acinetobacter
sp. strain Tol 5 has filamentous appendages and a hydrophobic cell surface, shows high adhesiveness to solid surfaces, and self-agglutinates. A “bald” mutant of this bacterium, strain T1, lacks the filamentous appendages and has decreased adhesiveness but retains a hydrophobic cell surface. We investigated the interaction between T1 cells and an organic solvent dispersed in an aqueous matrix. During a microbial-adhesion-to-hydrocarbon (MATH) test, which is frequently used to measure cell surface hydrophobicity, T1 cells adhered to hexadecane droplet surfaces in a monolayer, whereas wild-type cells aggregated on the droplet surfaces. The adsorbed T1 cells on the hexadecane surfaces hindered the coalescence of the droplets formed by vortexing, stabilizing the emulsion phase. Following the replacement of the aqueous phase with fresh pure water after the MATH test, a proportion of the T1 cells that had adsorbed to the hydrocarbon surface detached during further vortexing, suggesting a reversible adsorption of T1 cells. The final ratio of the adhering cells to the total cells in the detachment test coincided with that in the MATH test. The adhesion of T1 cells to the hydrocarbon surface conformed to the Langmuir adsorption isotherm, which describes reversible monolayer adsorption. Reversible monolayer adsorption should be useful for green technologies employing two-liquid-phase partitioning systems and for bioremediation because it allows effective reaction and transport of hydrophobic substrates at oil-water interfaces.
1-Aminocyclopropane-1-Carboxylate Deaminase Enhances
Agrobacterium tumefaciens
-Mediated Gene Transfer into Plant Cells
Authors: Nonaka Satoko , Sugawara Masayuki , Minamisawa Kiwamu , Yuhashi Ken-ichi , Ezura Hiroshi 
Published: March 2008

ABSTRACT

Agrobacterium
-mediated gene transfer is widely used for plant molecular genetics, and efficient techniques are required. Recent studies show that ethylene inhibits the gene transfer. To suppress ethylene evolution, we introduced 1-aminocyclopropane-1-carboxylate (ACC) deaminase into
Agrobacterium tumefaciens
. The ACC deaminase enhanced
A. tumefaciens
-mediated gene transfer into plants.
Removal of Odors from Swine Wastewater by Using Microbial Fuel Cells
Authors: Kim Jung Rae , Dec Jerzy , Bruns Mary Ann , Logan Bruce E. 
Published: March 2008

ABSTRACT

A single-chamber microbial fuel cell (MFC) was used to reduce 10 chemicals associated with odors by 99.76% (from 422 ± 23 μg/ml) and three volatile organic acids (acetate, butyrate, and propionate) by >99%. The MFC produced a maximum of 228 mW/m
2
and removed 84% of the organic matter in 260 h. MFCs were therefore effective at both treatment and electricity generation.
Requirement of a Plasmid-Encoded Catalase for Survival ofRhizobium etliCFN42 in a Polyphenol-Rich Environment
Authors: García-de los Santos Alejandro , López Erika , Cubillas Ciro A. , Noel K. Dale , Brom Susana , Romero David 
Published: March 2008

ABSTRACTNitrogen-fixing bacteria collectively called rhizobia are adapted to live in polyphenol-rich environments. The mechanisms that allow these bacteria to overcome toxic concentrations of plant polyphenols have not been clearly elucidated. We used a crude extract of polyphenols released from the seed coat of the black bean to simulate a polyphenol-rich environment and analyze the response of the bean-nodulating strainRhizobium etliCFN42. Our results showed that the viability of the wild type as well as that of derivative strains cured of plasmids p42a, p42b, p42c, and p42d or lacking 200 kb of plasmid p42e was not affected in this environment. In contrast, survival of the mutant lacking plasmid p42f was severely diminished. Complementation analysis revealed that thekatGgene located on this plasmid, encoding the only catalase present in this bacterium, restored full resistance to testa polyphenols. Our results indicate that oxidation of polyphenols due to interaction with bacterial cells results in the production of a high quantity of H2O2, whose removal by thekatG-encoded catalase plays a key role for cell survival in a polyphenol-rich environment.
Multiphasic Approach Reveals Genetic Diversity of Environmental and Patient Isolates of
Mycobacterium mucogenicum
and
Mycobacterium phocaicum
Associated with an Outbreak of Bacteremias at a Texas Hospital
Authors: Cooksey Robert C. , Jhung Michael A. , Yakrus Mitchell A. , Butler W. Ray , Adékambi Toidi , Morlock Glenn P. , Williams Margaret , Shams Alicia M. , Jensen Bette J. , Morey Roger E. , Charles Nadege , Toney Sean R. , Jost Kenneth C. , Dunbar Denise F. , Bennett Vickie , Kuan Marcella , Srinivasan Arjun 
Published: March 2008

ABSTRACT

Between March and May 2006, a Texas hospital identified five
Mycobacterium mucogenicum
bloodstream infections among hospitalized oncology patients using fluorescence high-performance liquid chromatography analysis of mycolic acids. Isolates from blood cultures were compared to 16 isolates from environmental sites or water associated with this ward. These isolates were further characterized by
hsp65
, 16S rRNA, and
rpoB
gene sequencing,
hsp65
PCR restriction analysis, and molecular typing methods, including repetitive element PCR, random amplified polymorphic DNA PCR, and pulsed-field gel electrophoresis (PFGE) of large restriction fragments. Three of five patient isolates were confirmed as
M. mucogenicum
and were in a single cluster as determined by all identification and typing methods. The remaining two patient isolates were identified as different strains of
Mycobacterium phocaicum
by
rpoB
sequence analysis. One of these matched an environmental isolate from a swab of a hand shower in the patient's room, while none of the clinical isolates of
M. mucogenicum
matched environmental strains. Among the other 15 environmental isolates, 11 were identified as
M. mucogenicum
and 4 as
M. phocaicum
strains, all of which were unrelated by typing methods. Although the 16S rRNA gene sequences matched for all 14
M. mucogenicum
isolates, there were two each of the
hsp65
and
rpoB
sequevars, seven PCR typing patterns, and 12 PFGE patterns. Among the seven
M. phocaicum
isolates were three 16S rRNA sequevars, two
hsp65
sequevars, two
rpoB
sequevars, six PCR typing patterns, and six PFGE patterns. This outbreak represents the first case of catheter-associated bacteremia caused by
M. phocaicum
and the first report of clinical isolates from a U.S. hospital. The investigation highlights important differences in the available typing methods for mycobacteria and demonstrates the genetic diversity of these organisms even within narrow confines of time and space.
Cloning and Heterologous Production of Hiracin JM79, a Sec-Dependent Bacteriocin Produced by
Enterococcus hirae
DCH5, in Lactic Acid Bacteria and
Pichia pastoris
Authors: Sánchez Jorge , Borrero Juan , Gómez-Sala Beatriz , Basanta Antonio , Herranz Carmen , Cintas Luis M. , Hernández Pablo E. 
Published: March 2008

ABSTRACT

Hiracin JM79 (HirJM79), a Sec-dependent bacteriocin produced by
Enterococcus hirae
DCH5, was cloned and produced in
Lactococcus lactis
,
Lactobacillus sakei
,
Enterococcus faecium
,
Enterococcus faecalis
, and
Pichia pastoris
. For heterologous production of HirJM79 in lactic acid bacteria (LAB), the HirJM79 structural gene (
hirJM79
), with or without the HirJM79 immunity gene (
hiriJM79
), was cloned into the plasmid pMG36c under the control of the constitutive promoter P
32
and into the plasmid pNZ8048 under the control of the inducible P
NisA
promoter. For the production of HirJM79 in
P. pastoris
, the gene encoding the mature HirJM79 protein was cloned into the pPICZαA expression vector. The recombinant plasmids permitted the production of biologically active HirJM79 in the supernatants of
L. lactis
IL1403,
L. lactis
NZ9000,
L. sakei
Lb790,
E. faecalis
JH2-2, and
P. pastoris
X-33, the coproduction of HirJM79 and nisin A in
L. lactis
DPC5598, and the coproduction of HirJM79 and enterocin P in
E. faecium
L50/14-2. All recombinant LAB produced larger quantities of HirJM79 than
E. hirae
DCH5, although the antimicrobial activities of most transformants were lower than that predicted from their production of HirJM79. The synthesis, processing, and secretion of HirJM79 proceed efficiently in recombinant LAB strains and
P. pastoris
.
Effects of Carbon Dioxide on Neurotoxin Gene Expression in NonproteolyticClostridium botulinumType E
Authors: Artin Ingrid , Carter Andrew T. , Holst Elisabet , Lövenklev Maria , Mason David R. , Peck Michael W. , Rådström Peter 
Published: March 2008

ABSTRACTCarbon dioxide is an antimicrobial gas commonly used in modified atmosphere packaging. In the present study, the effects of carbon dioxide on the growth of and neurotoxin production by nonproteolyticClostridium botulinumtype E were studied during the growth cycle. Quantitative reverse transcription-PCR and an enzyme-linked immunosorbent assay were used to quantify expression of the type E botulinum neurotoxin gene (cntE) and the formation of type E neurotoxin. The expression levels ofcntEwere similar in two strains, with relative expression peaking in the transition between exponential phase and stationary phase. In stationary phase,cntEmRNA expression declined rapidly. ThecntEmRNA half-life was calculated to be approximately 9 minutes. Neurotoxin formation occurred in late exponential phase and stationary phase. High carbon dioxide concentrations delayed growth by increasing the lag time and decreasing the maximum growth rate. The effects of carbon dioxide concentration on relative neurotoxin gene expression and neurotoxin formation were significant. Expression ofcntEmRNA and the formation of extracellular neurotoxin were twofold higher with a headspace carbon dioxide concentration of 70% (vol/vol) compared to 10% (vol/vol). This finding sheds a new, cautionary light on the potential risks of botulism associated with the use of modified atmosphere packaging.
Multiple Pathways for Triacylglycerol Biosynthesis in
Streptomyces coelicolor
Authors: Arabolaza Ana , Rodriguez Eduardo , Altabe Silvia , Alvarez Hector , Gramajo Hugo 
Published: March 2008

ABSTRACT

The terminal reaction in triacylglyceride (TAG) biosynthesis is the esterification of diacylglycerol (DAG) with a fatty acid molecule. To study this reaction in
Streptomyces coelicolor
, we analyzed three candidate genes (sco0958, sco1280, and sco0123) whose products significantly resemble the recently identified wax ester synthase/acyl-coenzyme A (CoA):DAG acyltransferase (DGAT) from
Acinetobacter baylyi
. The deletion of either sco0123 or sco1280 resulted in no detectable decrease in TAG accumulation. In contrast, the deletion of sco0958 produced a dramatic reduction in neutral lipid production, whereas the overexpression of this gene yielded a significant increase in de novo TAG biosynthesis. In vitro activity assays showed that Sco0958 mediates the esterification of DAG using long-chain acyl-CoAs (C
14
to C
18
) as acyl donors. The

K
m

and
V
max
values of this enzyme for myristoyl-CoA were 45 μM and 822 nmol mg
−1
min
−1
, respectively. Significantly, the triple mutant strain was not completely devoid of storage lipids, indicating the existence of alternative TAG-biosynthetic routes. We present strong evidence demonstrating that the residual production of TAG in this mutant strain is mediated, at least in part, by an acyl-CoA-dependent pathway, since the triple mutant still exhibited DGAT activity. More importantly, there was substantial phospholipid:DGAT (PDAT) activity in the wild type and in the triple mutant. This is the first time that a PDAT activity has been reported for bacteria, highlighting the extreme metabolic diversity of this industrially important soil microorganism.
MORN1 Has a Conserved Role in Asexual and Sexual Development across the Apicomplexa
Authors: Ferguson David J. P. , Sahoo Nivedita , Pinches Robert A. , Bumstead Janene M. , Tomley Fiona M. , Gubbels Marc-Jan 
Published: March 2008

ABSTRACT

The gene encoding the membrane occupation and recognition nexus protein MORN1 is conserved across the Apicomplexa. In
Toxoplasma gondii
, MORN1 is associated with the spindle poles, the anterior and posterior rings of the inner membrane complex (IMC). The present study examines the localization of MORN1 during the coccidian development of
T. gondii
and three
Eimeria
species (in the definitive host) and erythrocytic schizogony of
Plasmodium falciparum
. During asexual proliferation, MORN1 is associated with the posterior ring of the IMCs of the multiple daughters forming during
T. gondii
endopolygeny and schizogony in
Eimeria
and
P. falciparum
. Furthermore, the expression of
P. falciparum
MORN1 protein peaked in late schizogony. These data fit a model with a conserved role for MORN1 during IMC assembly in all variations of asexual development. An important new observation is the reactivity of MORN1 antibody with certain sexual stages in
T. gondii
and
Eimeria
species. Here MORN1 is organized as a ring-like structure where the microgametes bud from the microgametocyte while in mature microgametes it is present near the flagellar basal bodies and mitochondrion. These observations suggest a conserved role for MORN1 in both asexual and sexual development across the Apicomplexa.
The Heterotrophic DinoflagellateCrypthecodinium cohniiDefines a Model Genetic System To Investigate Cytoplasmic Starch Synthesis
Authors: Deschamps Philippe , Guillebeault Delphine , Devassine Jimi , Dauvillée David , Haebel Sophie , Steup Martin , Buléon Alain , Putaux Jean-Luc , Slomianny Marie-Christine , Colleoni Christophe , Devin Aline , Plancke Charlotte , Tomavo Stanislas , Derelle Evelyne , Moreau Hervé , Ball Steven 
Published: March 2008

ABSTRACTThe nature of the cytoplasmic pathway of starch biosynthesis was investigated in the model heterotrophic dinoflagellateCrypthecodinium cohnii. The storage polysaccharide granules were shown to be composed of both amylose and amylopectin fractions with a chain length distribution and crystalline organization very similar to those of green algae and land plant starch. Preliminary characterization of the starch pathway demonstrated thatC. cohniicontains multiple forms of soluble starch synthases and one major 110-kDa granule-bound starch synthase. All purified enzymes displayed a marked substrate preference for UDP-glucose. At variance with most other microorganisms, the accumulation of starch in the dinoflagellate occurs during early and mid-log phase, with little or no synthesis witnessed when approaching stationary phase. In order to establish a genetic system allowing the study of cytoplasmic starch metabolism in eukaryotes, we describe the isolation of marker mutations and the successful selection of random recombinant populations after homothallic crosses.
Novel Arrangement of Enhancer Sequences for NifA-Dependent Activation of the Hydrogenase Gene Promoter in
Rhizobium leguminosarum
bv. viciae
Authors: Martínez Marta , Colombo Maria-Victoria , Palacios Jose-Manuel , Imperial Juan , Ruiz-Argüeso Tomás 
Published: March 2008

ABSTRACT

The transcriptional activation of the NifA-dependent σ
54
promoter of the
Rhizobium leguminosarum
hydrogenase structural genes
hupSL
(P
1
) has been studied through gel retardation analysis and detailed mutagenesis. Gel retardation analysis indicated the existence of a physical interaction between NifA and the promoter. Extensive mutagenesis followed by in vivo expression analysis showed that three sequences of 4 bases each (−170 ACAA −167, −161 ACAA −158, and −145 TTGT −142) are required for maximal stimulation of in vivo transcription of the P
1
promoter. The arrangement of these upstream activating sequences (ACAA N
5
ACAA N
12
TTGT) differs from the canonical 5′ACA N
10
TGT 3′ UAS structure involved in NifA-dependent activation of
nif/fix
genes. Mutant promoter analysis indicated that the relative contribution of each of these sequences to P
1
promoter activity increases with its proximity to the transcription start site. Analysis of double mutants altered in two out of the three enhancer sequences suggests that each of these sequences functions in NifA-dependent activation of the P
1
promoter in an independent but cooperative mode. The similarities and differences between
cis
elements of
hup
and
nif/fix
promoters suggest that the structure of the P
1
promoter has adapted to activation by NifA in order to coexpress hydrogenase and nitrogenase activities in legume nodules.
Biochemical and Phylogenetic Characterization of a Novel Diaminopimelate Biosynthesis Pathway in Prokaryotes Identifies a Diverged Form of
ll
-Diaminopimelate Aminotransferase
Authors: Hudson André O. , Gilvarg Charles , Leustek Thomas 
Published: March 2008

ABSTRACT

A variant of the diaminopimelate (DAP)-lysine biosynthesis pathway uses an
ll
-DAP aminotransferase (DapL, EC 2.6.1.83) to catalyze the direct conversion of
l
-2,3,4,5-tetrahydrodipicolinate to
ll
-DAP. Comparative genomic analysis and experimental verification of DapL candidates revealed the existence of two diverged forms of DapL (DapL1 and DapL2). DapL orthologs were identified in eubacteria and archaea. In some species the corresponding
dapL
gene was found to lie in genomic contiguity with other
dap
genes, suggestive of a polycistronic structure. The DapL candidate enzymes were found to cluster into two classes sharing approximately 30% amino acid identity. The function of selected enzymes from each class was studied. Both classes were able to functionally complement
Escherichia coli dapD
and
dapE
mutants and to catalyze
ll
-DAP transamination, providing functional evidence for a role in DAP/lysine biosynthesis. In all cases the occurrence of
dapL
in a species correlated with the absence of genes for
dapD
and
dapE
representing the acyl DAP pathway variants, and only in a few cases was
dapL
coincident with
ddh
encoding
meso
-DAP dehydrogenase. The results indicate that the DapL pathway is restricted to specific lineages of eubacteria including the
Cyanobacteria
,
Desulfuromonadales
,
Firmicutes
,
Bacteroidetes
,
Chlamydiae
,
Spirochaeta
, and
Chloroflexi
and two archaeal groups, the
Methanobacteriaceae
and
Archaeoglobaceae.
Chlamydia pneumoniaeGroEL1 Protein Is Cell Surface Associated and Required for Infection of HEp-2 Cells
Authors: Wuppermann Frederik N. , Mölleken Katja , Julien Marion , Jantos Christian A. , Hegemann Johannes H. 
Published: March 2008

ABSTRACTChlamydia pneumoniaeis an important obligate intracellular pathogen that replicates within an inclusion in the eukaryotic cell. The initial event of a chlamydial infection is the adherence to and subsequent uptake of the infectious elementary bodies (EBs) by the human cell. These processes require yet-unidentified bacterial and eukaryotic surface proteins. The GroEL1 protein, which exhibits a very strong antigenicity and in vitro can activate various eukaryotic cells, is a potential pathogenicity factor. We localized the protein during the infection process and found it in the inclusion but outside the chlamydial particles. GroEL1 was also localized on the surface of EBs, and the protein could be washed off the EBs. Latex beads coated with recombinantly produced GroEL1 (rGroEL1) bound in a dose-dependent manner to HEp-2 cells. Likewise, GroEL1, when expressed and displayed on the yeast cell surface, mediated adhesion to HEp-2 cells. Interestingly, the homologous GroEL2 and GroEL3 proteins showed no adhesive properties. Incubation of primary umbilical vein endothelial cells with soluble GroEL1 and GroEL1-coated latex beads activated the translocation of the general transcription factor NF-κB into the nucleus. Finally, preincubation of HEp-2 cells with rGroEL1 significantly reduced subsequent infection withC. pneumoniae, although adhesion of infectious bacteria to eukaryotic cells was not affected. Taken together, these data support a role for extracellular GroEL1 in the establishment of the chlamydial infection.
Characterization of the Periplasmic Domain of MotB and Implications for Its Role in the Stator Assembly of the Bacterial Flagellar Motor
Authors: Kojima Seiji , Furukawa Yukio , Matsunami Hideyuki , Minamino Tohru , Namba Keiichi 
Published: March 2008

ABSTRACT

MotA and MotB are integral membrane proteins that form the stator complex of the proton-driven bacterial flagellar motor. The stator complex functions as a proton channel and couples proton flow with torque generation. The stator must be anchored to an appropriate place on the motor, and this is believed to occur through a putative peptidoglycan-binding (PGB) motif within the C-terminal periplasmic domain of MotB. In this study, we constructed and characterized an N-terminally truncated variant of
Salmonella enterica
serovar Typhimurium MotB consisting of residues 78 through 309 (MotB
C
). MotB
C
significantly inhibited the motility of wild-type cells when exported into the periplasm. Some point mutations in the PGB motif enhanced the motility inhibition, while an in-frame deletion variant, MotB
C
(Δ197-210), showed a significantly reduced inhibitory effect. Wild-type MotB
C
and its point mutant variants formed a stable homodimer, while the deletion variant was monomeric. A small amount of MotB was coisolated only with the secreted form of MotB
C
-His
6
by Ni-nitrilotriacetic acid affinity chromatography, suggesting that the motility inhibition results from MotB-MotB
C
heterodimer formation in the periplasm. However, the monomeric mutant variant MotB
C
(Δ197-210) did not bind to MotB, suggesting that MotB
C
is directly involved in stator assembly. We propose that the MotB
C
dimer domain plays an important role in targeting and stable anchoring of the MotA/MotB complex to putative stator-binding sites of the motor.
Twitching Motility Is Essential for Virulence in
Dichelobacter nodosus
Authors: Han Xiaoyan , Kennan Ruth M. , Davies John K. , Reddacliff Leslie A. , Dhungyel Om P. , Whittington Richard J. , Turnbull Lynne , Whitchurch Cynthia B. , Rood Julian I. 
Published: March 2008

ABSTRACT

Type IV fimbriae are essential virulence factors of
Dichelobacter nodosus
, the principal causative agent of ovine foot rot. The
fimA
fimbrial subunit gene is required for virulence, but
fimA
mutants exhibit several phenotypic changes and it is not certain if the effects on virulence result from the loss of type IV fimbria-mediated twitching motility, cell adherence, or reduced protease secretion. We showed that mutation of either the
pilT
or
pilU
gene eliminated the ability to carry out twitching motility. However, the
pilT
mutants displayed decreased adhesion to epithelial cells and reduced protease secretion, whereas the
pilU
mutants had wild-type levels of extracellular protease secretion and adherence. These data provided evidence that PilT is required for the type IV fimbria-dependent protease secretion pathway in
D. nodosus
. It was postulated that sufficient fimbrial retraction must occur in the
pilU
mutants to allow protease secretion, but not twitching motility, to take place. Although no cell movement was detected in a
pilU
mutant of
D. nodosus
, aberrant motion was detected in an equivalent mutant of
Pseudomonas aeruginosa
. These observations explain how in
D. nodosus
protease secretion can occur in a
pilU
mutant but not in a
pilT
mutant. In addition, virulence studies with sheep showed that both the
pilT
and
pilU
mutants were avirulent, providing evidence that mutation of the type IV fimbrial system affects virulence by eliminating twitching motility, not by altering cell adherence or protease secretion.