bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lactococcin Q, a Novel Two-Peptide Bacteriocin Produced by
Lactococcus lactis
QU 4
Authors: Zendo Takeshi , Koga Shoko , Shigeri Yasushi , Nakayama Jiro , Sonomoto Kenji 
Published: May 2006

ABSTRACT

A bacteriocin-producing strain,
Lactococcus lactis
QU 4, was isolated from corn. The bacteriocin, termed lactococcin Q, showed antibacterial activity only against
L. lactis
strains among a wide range of gram-positive indicator strains tested. Lactococcin Q was purified by acetone precipitation, cation exchange chromatography, and reverse-phase chromatography. Lactococcin Q consisted of two peptides, α and β, whose molecular masses were determined to be 4,260.43 Da and 4,018.36 Da, respectively. Amino acid and DNA sequencing analyses revealed that lactococcin Q was a novel two-peptide bacteriocin, homologous to lactococcin G. Comparative study using chemically synthesized lactococcin Q (Qα plus Qβ) and lactococcin G (Gα plus Gβ) clarified that hybrid combinations (Qα plus Gβ and Gα plus Qβ) as well as original combinations showed antibacterial activity, although each single peptide showed no significant activity. These four pairs of lactococcin peptides acted synergistically at a 1:1 molar ratio and exhibited identical antibacterial spectra but differed in MIC. The MIC of Qα plus Gβ was 32 times higher than that of Qα plus Qβ, suggesting that the difference in β peptides was important for the intensity of antibacterial activity.
Dissemination of Fluoroquinolone-Resistant
Campylobacter
spp. within an Integrated Commercial Poultry Production System
Authors: Idris Umelaalim , Lu Jingrang , Maier Marie , Sanchez Susan , Hofacre Charles L. , Harmon Barry G. , Maurer John J. , Lee Margie D. 
Published: May 2006

ABSTRACT

While characterizing the intestinal bacterial community of broiler chickens, we detected ε-proteobacterial DNA in the ilea of 3-day-old commercial broiler chicks (J. Lu, U. Idris, B. Harmon, C. Hofacre, J. J. Maurer, and M. D. Lee, Appl. Environ. Microbiol.
69:
6816-6824, 2003). The sequences exhibited high levels of similarity to
Campylobacter jejuni
and
Campylobacter coli
sequences, suggesting that chickens can carry
Campylobacter
at a very young age.
Campylobacter
sp. was detected by PCR in all samples collected from the ilea of chicks that were 3 to 49 days old; however, it was detected only in the cecal contents of chickens that were at least 21 days old. In order to determine whether the presence of
Campylobacter
DNA in young chicks was due to ingestion of the bacteria in food or water, we obtained commercial broiler hatching eggs, which were incubated in a research facility until the chicks hatched. DNA sequencing of the amplicons resulting from
Campylobacter
-specific 16S PCR performed with the ileal, cecal, and yolk contents of the day-of-hatching chicks revealed that
Campylobacter
DNA was present before the chicks consumed food or water. The 16S rRNA sequences exhibited 99% similarity to
C. jejuni
and
C. coli
sequences and 95 to 98% similarity to sequences of other thermophilic
Campylobacter
species, such as
C. lari
and
C. upsaliensis
. The presence of
C. coli
DNA was detected by specific PCR in the samples from chicks obtained from a commercial hatchery; however, no
Campylobacter
was detected by culturing. In order to determine whether the same strains of bacteria were present in multiple levels of the integrator, we cultured
Campylobacter
sp. from a flock of broiler breeders and their 6-week-old progeny that resided on a commercial broiler farm. The broiler breeders had been given fluoroquinolone antibiotics, and we sought to determine whether the same fluoroquinolone-resistant strain was present in their progeny. The isolates were typed by pulsed-field gel electrophoresis, which confirmed that the parental and progeny flocks contained the same strain of fluoroquinolone-resistant
C. coli
. These data indicate that resistant
C. coli
can be present in multiple levels of an integrated poultry system and demonstrated that molecular techniques or more sensitive culture methods may be necessary to detect early colonization by
Campylobacter
in broiler chicks.
Characterization of an Exo-β-1,3-Galactanase from
Clostridium thermocellum
Authors: Ichinose Hitomi , Kuno Atsushi , Kotake Toshihisa , Yoshida Makoto , Sakka Kazuo , Hirabayashi Jun , Tsumuraya Yoichi , Kaneko Satoshi 
Published: May 2006

ABSTRACT

A gene encoding an exo-β-1,3-galactanase from
Clostridium thermocellum
, Ct1,3Gal43A, was isolated. The sequence has similarity with an exo-β-1,3-galactanase of
Phanerochaete chrysosporium
(Pc1,3Gal43A). The gene encodes a modular protein consisting of an N-terminal glycoside hydrolase family 43 (GH43) module, a family 13 carbohydrate-binding module (CBM13), and a C-terminal dockerin domain. The gene corresponding to the GH43 module was expressed in
Escherichia coli
, and the gene product was characterized. The recombinant enzyme shows optimal activity at pH 6.0 and 50°C and catalyzes hydrolysis only of β-1,3-linked galactosyl oligosaccharides and polysaccharides. High-performance liquid chromatography analysis of the hydrolysis products demonstrated that the enzyme produces galactose from β-1,3-galactan in an exo-acting manner. When the enzyme acted on arabinogalactan proteins (AGPs), the enzyme produced oligosaccharides together with galactose, suggesting that the enzyme is able to accommodate a β-1,6-linked galactosyl side chain. The substrate specificity of the enzyme is very similar to that of Pc1,3Gal43A, suggesting that the enzyme is an exo-β-1,3-galactanase. Affinity gel electrophoresis of the C-terminal CBM13 did not show any affinity for polysaccharides, including β-1,3-galactan. However, frontal affinity chromatography for the CBM13 indicated that the CBM13 specifically interacts with oligosaccharides containing a β-1,3-galactobiose, β-1,4-galactosyl glucose, or β-1,4-galactosyl
N
-acetylglucosaminide moiety at the nonreducing end. Interestingly, CBM13 in the C terminus of Ct1,3Gal43A appeared to interfere with the enzyme activity toward β-1,3-galactan and α-
l
-arabinofuranosidase-treated AGP.
A Single Monooxygenase, Ese, Is Involved in the Metabolism of the Organochlorides Endosulfan and Endosulfate in an
Arthrobacter
sp
Authors: Weir Kahli M. , Sutherland Tara D. , Horne Irene , Russell Robyn J. , Oakeshott John G. 
Published: May 2006

ABSTRACT

In this paper we describe isolation of a bacterium capable of degrading both isomers of the organochloride insecticide endosulfan and its toxic metabolite, endosulfate. The bacterium was isolated from a soil microbial population that was enriched with continuous pressure to use endosulfate as the sole source of sulfur. Analysis of the 16S rRNA sequence of the bacterium indicated that it was an
Arthrobacter
species. The organochloride-degrading activity was not observed in the presence of sodium sulfite as an alternative sulfur source, suggesting that the activity was part of the sulfur starvation response of the strain. A gene,
ese
, encoding an enzyme capable of degrading both isomers of endosulfan and endosulfate was isolated from this bacterium. The enzyme belongs to the two-component flavin-dependent monooxygenase family whose members require reduced flavin for activity. Nuclear magnetic resonance analyses identified the metabolite of endosulfan as endosulfan monoalcohol and the metabolite of endosulfate as endosulfan hemisulfate. The
ese
gene was located in a cluster of 10 open reading frames encoding proteins with low levels of sulfur-containing amino acids. These open reading frames were organized into two apparent divergently orientated operons and a gene encoding a putative LysR-type transcriptional regulator. The operon not containing
ese
did contain a homologue whose product exhibited 62% amino acid identity to the
ese
-encoded protein.
Coupled Photochemical and Enzymatic Mn(II) Oxidation Pathways of a Planktonic
Roseobacter
-Like Bacterium
Authors: Hansel Colleen M. , Francis Chris A. 
Published: May 2006

ABSTRACT

Bacteria belonging to the
Roseobacter
clade of the α-
Proteobacteria
occupy a wide range of environmental niches and are numerically abundant in coastal waters. Here we reveal that
Roseobacter
-like bacteria may play a previously unrecognized role in the oxidation and cycling of manganese (Mn) in coastal waters. A diverse array of Mn(II)-oxidizing
Roseobacter
-like species were isolated from Elkhorn Slough, a coastal estuary adjacent to Monterey Bay in California. One isolate (designated AzwK-3b), in particular, rapidly oxidizes Mn(II) to insoluble Mn(III, IV) oxides. Interestingly, AzwK-3b is 100% identical (at the 16S rRNA gene level) to a previously described
Pfiesteria
-associated
Roseobacter
-like bacterium, which is not able to oxidize Mn(II). The rates of manganese(II) oxidation by live cultures and cell-free filtrates are substantially higher when the preparations are incubated in the presence of light. The rates of oxidation by washed cell extracts, however, are light independent. Thus, AzwK-3b invokes two Mn(II) oxidation mechanisms when it is incubated in the presence of light, in contrast to the predominantly direct enzymatic oxidation in the dark. In the presence of light, production of photochemically active metabolites is coupled with initial direct enzymatic Mn(II) oxidation, resulting in higher Mn(II) oxidation rates. Thus,
Roseobacter
-like bacteria may not only play a previously unrecognized role in Mn(II) oxidation and cycling in coastal surface waters but also induce a novel photooxidation pathway that provides an alternative means of Mn(II) oxidation in the photic zone.
Dynamics of a Pig Slurry Microbial Community during Anaerobic Storage and Management
Authors: Peu Pascal , Brugère Hubert , Pourcher Anne-Marie , Kérourédan Monique , Godon Jean-Jacques , Delgenès Jean-Philippe , Dabert Patrick 
Published: May 2006

ABSTRACT

The microbial community of a pig slurry on a farm was monitored for 6 months using both molecular and cultural approaches. Sampling was carried out at all the different stages of effluent handling, from the rearing build-up to slurry spreading. Total DNA of each sample was extracted and analyzed by PCR-single-strand conformation polymorphism (SSCP) analysis using primers targeting the 16S rRNA genes from the archaeal and bacterial domains and also the
Eubacterium
-
Clostridium
,
Bacillus-Streptococcus-Lactobacillus
, and
Bacteroides-Prevotella
groups. A comparison of the SSCP profiles showed that there were rapid changes in the dominant bacterial community during the first 2 weeks of anaerobic storage and that the community was relatively stable thereafter. Several bacterial populations, identified as populations closely related to uncultured
Clostridium
and
Porphyromonas
and to
Lactobacillus
and
Streptococcus
cultured species commonly isolated from pig feces, remained present and dominant from the rearing build-up to the time of spreading. Enumeration of fecal indicators (enterococci and
Escherichia coli
) performed in parallel using cultural methods revealed the same trends. On the other hand, the archaeal community adapted slowly during pig slurry storage, and its diversity increased. A shift between two hydrogenotrophic methanogenic
Methanobrevibacter
populations from the storage pit to the pond was observed. Microorganisms present in pig slurry at the time of spreading could not be detected in soil after spreading by either molecular or cultural techniques, probably because of the detection limit inherent in the two techniques.
Two Routes of Metabolic Cross-Feeding betweenBifidobacterium adolescentisand Butyrate-Producing Anaerobes from the Human Gut
Authors: Belenguer Alvaro , Duncan Sylvia H. , Calder A. Graham , Holtrop Grietje , Louis Petra , Lobley Gerald E. , Flint Harry J. 
Published: May 2006

ABSTRACTDietary carbohydrates have the potential to influence diverse functional groups of bacteria within the human large intestine. Of 12Bifidobacteriumstrains of human gut origin from seven species tested, four grew in pure culture on starch and nine on fructo-oligosaccharides. The potential for metabolic cross-feeding betweenBifidobacterium adolescentisand lactate-utilizing, butyrate-producingFirmicutebacteria related toEubacterium halliiandAnaerostipes caccaewas investigated in vitro.E. halliiL2-7 andA. caccaeL1-92 failed to grow on starch in pure culture, but in coculture withB. adolescentisL2-32 butyrate was formed, indicating cross-feeding of metabolites to the lactate utilizers. Studies with [13C]lactate confirmed carbon flow from lactate, via acetyl coenzyme A, to butyrate both in pure cultures ofE. halliiand in cocultures withB. adolescentis. Similar results were obtained in cocultures involvingB. adolescentisDSM 20083 with fructo-oligosaccharides as the substrate. Butyrate formation was also stimulated, however, in cocultures ofB. adolescentisL2-32 grown on starch or fructo-oligosaccharides withRoseburiasp. strain A2-183, which produces butyrate but does not utilize lactate. This is probably a consequence of the release byB. adolescentisof oligosaccharides that are available toRoseburiasp. strain A2-183. We conclude that two distinct mechanisms of metabolic cross-feeding betweenB. adolescentisand butyrate-forming bacteria may operate in gut ecosystems, one due to consumption of fermentation end products (lactate and acetate) and the other due to cross-feeding of partial breakdown products from complex substrates.
Microeukaryote Community Patterns along an O2/H2S Gradient in a Supersulfidic Anoxic Fjord (Framvaren, Norway)
Authors: Behnke Anke , Bunge John , Barger Kathryn , Breiner Hans-Werner , Alla Victoria , Stoeck Thorsten 
Published: May 2006

ABSTRACTTo resolve the fine-scale architecture of anoxic protistan communities, we conducted a cultivation-independent 18S rRNA survey in the superanoxic Framvaren Fjord in Norway. We generated three clone libraries along the steep O2/H2S gradient, using the multiple-primer approach. Of 1,100 clones analyzed, 753 proved to be high-quality protistan target sequences. These sequences were grouped into 92 phylotypes, which displayed high protistan diversity in the fjord (17 major eukaryotic phyla). Only a few were closely related to known taxa. Several sequences were dissimilar to all previously described sequences and occupied a basal position in the inferred phylogenies, suggesting that the sequences recovered were derived from novel, deeply divergent eukaryotes. We detected sequence clades with evolutionary importance (for example, clades in the euglenozoa) and clades that seem to be specifically adapted to anoxic environments, challenging the hypothesis that the global dispersal of protists is uniform. Moreover, with the detection of clones affiliated with jakobid flagellates, we present evidence that primitive descendants of early eukaryotes are present in this anoxic environment. To estimate sample coverage and phylotype richness, we used parametric and nonparametric statistical methods. The results show that although our data set is one of the largest published inventories, our sample missed a substantial proportion of the protistan diversity. Nevertheless, statistical and phylogenetic analyses of the three libraries revealed the fine-scale architecture of anoxic protistan communities, which may exhibit adaptation to different environmental conditions along the O2/H2S gradient.
Identification and Localization of a
Rickettsia
sp. in
Bemisia tabaci
(Homoptera: Aleyrodidae)
Authors: Gottlieb Yuval , Ghanim Murad , Chiel Elad , Gerling Dan , Portnoy Vitaly , Steinberg Shimon , Tzuri Galil , Horowitz A. Rami , Belausov Eduard , Mozes-Daube Neta , Kontsedalov Svetlana , Gershon Moshe , Gal Shunit , Katzir Nurit , Zchori-Fein Einat 
Published: May 2006

ABSTRACT

Whiteflies (Homoptera: Aleyrodidae) are sap-sucking insects that harbor “
Candidatus
Portiera aleyrodidarum,” an obligatory symbiotic bacterium which is housed in a special organ called the bacteriome. These insects are also home for a diverse facultative microbial community which may include
Hamiltonella
,
Arsenophonus
,
Fritchea
,
Wolbachia
, and
Cardinium
spp. In this study, the bacteria associated with a B biotype of the sweet potato whitefly
Bemisia tabaci
were characterized using molecular fingerprinting techniques, and a
Rickettsia
sp. was detected for the first time in this insect family.
Rickettsia
sp. distribution, transmission and localization were studied using PCR and fluorescence in situ hybridizations (FISH).
Rickettsia
was found in all 20 Israeli
B. tabaci
populations screened but not in all individuals within each population. A FISH analysis of
B. tabaci
eggs, nymphs, and adults revealed a unique concentration of
Rickettsia
around the gut and follicle cells, as well as a random distribution in the hemolymph. We postulate that the
Rickettsia
enters the oocyte together with the bacteriocytes, leaves these symbiont-housing cells when the egg is laid, multiplies and spreads throughout the egg during embryogenesis and, subsequently, disperses throughout the body of the hatching nymph, excluding the bacteriomes. Although the role
Rickettsia
plays in the biology of the whitefly is currently unknown, the vertical transmission on the one hand and the partial within-population infection on the other suggest a phenotype that is advantageous under certain conditions but may be deleterious enough to prevent fixation under others.
Effects of Quaternary Ammonium Silane Coatings on Mixed Fungal and Bacterial Biofilms on Tracheoesophageal Shunt Prostheses
Authors: Oosterhof Janine J. H. , Buijssen Kevin J. D. A. , Busscher Henk J. , van der Laan Bernard F. A. M. , van der Mei Henny C. 
Published: May 2006

ABSTRACT
Two quaternary ammonium silanes (QAS) were used to coat silicone rubber tracheoesophageal shunt prostheses, yielding a positively charged surface. One QAS coating [(trimethoxysilyl)-propyldimethyloctadecylammonium chloride] was applied through chemical bonding, while the other coating, Biocidal ZF, was sprayed onto the silicone rubber surface. The sprayed coating lost its stability within an hour, while the chemically bonded coating appeared stable. Upon incubation in an artificial throat model, allowing simultaneous adhesion and growth of yeast and bacteria, all coated prostheses showed significant reductions in the numbers of viable yeast (to 12% to 16%) and bacteria (to 27% to 36%) compared with those for silicone rubber controls, as confirmed using confocal laser scanning microscopy after live/dead staining of the biofilms. In situ hybridization with fluorescently labeled oligonucleotide probes showed that yeasts expressed hyphae on the untreated and Biocidal ZF-coated prostheses but not on the QAS-coated prostheses. Whether this is a result of the positive QAS coating or is due to the reduced number of bacteria is currently unknown. In summary, this is the first report on the inhibitory effects of positively charged coatings on the viability of yeasts and bacteria in mixed biofilms. Although the study initially aimed at reducing voice prosthetic biofilms, its relevance extends to all biomedical and environmental surfaces where mixed biofilms develop and present a problem.
Molecular Epidemiology of
Haemophilus influenzae
Type b Causing Vaccine Failures in the United Kingdom
Authors: Aracil Belén , Slack Mary , Pérez-Vázquez María , Román Federico , Ramsay Mary , Campos José 
Published: May 2006

ABSTRACT

Haemophilus influenzae
type b (Hib) was a major cause of pediatric disease in the United Kingdom prior to the introduction of routine Hib immunization in 1992. An unexpected resurgence of cases of vaccine failure was observed with fully vaccinated children from 1999 onward. We investigated whether Hib isolates causing vaccine failures in the United Kingdom could have undergone a change in their population structure to elude the protective effect of Hib vaccine. Molecular epidemiology studies were carried out with 376 isolates from invasive infections (164 vaccine failures and 212 controls). Genetic variability was higher in controls than in vaccine failures. Of the four major clusters obtained, cluster I comprised 92.2% of the total isolates: 156 vaccine failures (95%) and 193 (91%) controls. Cluster IV was specific for vaccine failures but included only four isolates. The increased number of cases of invasive Hib in fully vaccinated children in the United Kingdom was caused by isolates belonging not to a particular or new genotype but to genotypes already circulating in the prevaccination era, before conjugate Hib vaccines were available.
Nutritional Requirements and Antibiotic Resistance Patterns ofHelicobacterSpecies in Chemically Defined Media
Authors: Testerman Traci L. , Conn P. Brian , Mobley Harry L. T. , McGee David J. 
Published: May 2006

ABSTRACTThe growth of the gastric pathogenHelicobacter pyloriin the absence of serum remains challenging, and nutritional requirements have only partially been defined, while almost nothing is known about nutritional requirements of otherHelicobacterspp. Although previous data showed thatH. pylorigrows in the chemically defined medium F-12, but not in other tissue culture media examined, the specific components responsible for growth were not entirely understood. Here we describe the optimization of amino acids, metals, and sodium chloride forH. pylori. Iron, zinc, and magnesium were critical for growth; copper was not required. Optimization of sodium chloride was further beneficial. Nutritional requirements and antibiotic resistance patterns of several otherHelicobacterspp. revealed that all exceptH. felisgrew in serum-free, unsupplemented F-12. AllHelicobacterspp. were resistant to at least six antimicrobial agents when cultured in the presence of serum. However, in the absence of serum,H. pylori,H. mustelae, andH. muridarumbecame sensitive to polymyxin B and/or trimethoprim. Much of the data were obtained using a convenient ATP assay to quantify growth.H. pylorihas surprisingly few absolute requirements for growth: 9 amino acids, sodium and potassium chloride, thiamine, iron, zinc, magnesium, hypoxanthine, and pyruvate. These data suggest thatH. pyloriand otherHelicobacterspp. are not as fastidious as previously thought. The data also suggest that chemically defined media described herein could yield the growth of a wide range ofHelicobacterspp., allowing a more detailed characterization ofHelicobacterphysiology and interactions with host cells.