bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Microbial Inoculants on the Indigenous Actinobacterial Endophyte Population in the Roots of Wheat as Determined by Terminal Restriction Fragment Length Polymorphism
Authors: Conn Vanessa M. , Franco Christopher M. M. 
Published: November 2004

ABSTRACT

The effect of single actinobacterial endophyte seed inoculants and a mixed microbial soil inoculant on the indigenous endophytic actinobacterial population in wheat roots was investigated by using the molecular technique terminal restriction fragment length polymorphism (T-RFLP). Wheat was cultivated either from seeds coated with the spores of single pure actinobacterial endophytes of
Microbispora
sp. strain EN2,
Streptomyces
sp. strain EN27, and
Nocardioides albus
EN46 or from untreated seeds sown in soil with and without a commercial mixed microbial soil inoculant. The endophytic actinobacterial population within the roots of 6-week-old wheat plants was assessed by T-RFLP. Colonization of the wheat roots by the inoculated actinobacterial endophytes was detected by T-RFLP, as were 28 to 42 indigenous actinobacterial genera present in the inoculated and uninoculated plants. The presence of the commercial mixed inoculant in the soil reduced the endophytic actinobacterial diversity from 40 genera to 21 genera and reduced the detectable root colonization by approximately half. The results indicate that the addition of a nonadapted microbial inoculum to the soil disrupted the natural actinobacterial endophyte population, reducing diversity and colonization levels. This was in contrast to the addition of a single actinobacterial endophyte to the wheat plant, where the increase in colonization level could be confirmed even though the indigenous endophyte population was not adversely affected.
Relationships of a Novel Lyme Disease Spirochete,
Borrelia spielmani
sp. nov., with Its Hosts in Central Europe
Authors: Richter Dania , Schlee Daniela B. , Allgöwer Rainer , Matuschka Franz-Rainer 
Published: November 2004

ABSTRACT

To determine whether the pathogenic variant of Lyme disease spirochetes, isolate A14S, is perpetuated in a particular reservoir-vector relationship, we screened vector ticks in various Central European sites for a related spirochete and determined its host association. A14S-like spirochetes infect numerous questing ticks in the Petite Camargue Alsacienne (PC). They frequently infect dormice, but no mice or voles. Garden dormice appear to be better reservoir hosts for A14S-like spirochetes than for
Borrelia afzelii
, because these spirochetes are retained longer and infect ticks more readily. Spirochetes associated with garden dormice in the PC site form a homologous entity with those isolated from a human patient in The Netherlands. Its unique biological relationship together with previous genetic characterization justifies designating this dormouse-associated genospecies as a distinct entity. Garden dormice serve as the main reservoir hosts of a novel genospecies,
Borrelia spielmani
sp. nov., one of several that cause Lyme disease in people.
Escherichia coli
Contamination of Vegetables Grown in Soils Fertilized with Noncomposted Bovine Manure: Garden-Scale Studies
Authors: Ingham Steven C. , Losinski Jill A. , Andrews Matthew P. , Breuer Jane E. , Breuer Jeffry R. , Wood Timothy M. , Wright Thomas H. 
Published: November 2004

ABSTRACT

In this study we tested the validity of the National Organic Program (NOP) requirement for a ≥120-day interval between application of noncomposted manure and harvesting of vegetables grown in manure-fertilized soil. Noncomposted bovine manure was applied to 9.3-m
2
plots at three Wisconsin sites (loamy sand, silt loam, and silty clay loam) prior to spring and summer planting of carrots, radishes, and lettuce. Soil and washed (30 s under running tap water) vegetables were analyzed for indigenous
Escherichia coli
. Within 90 days, the level of
E. coli
in manure-fertilized soil generally decreased by about 3 log CFU/g from initial levels of 4.2 to 4.4 log CFU/g. Low levels of
E. coli
generally persisted in manure-fertilized soil for more than 100 days and were detected in enriched soil from all three sites 132 to 168 days after manure application. For carrots and lettuce, at least one enrichment-negative sample was obtained ≤100 days after manure application for 63 and 88% of the treatments, respectively. The current ≥120-day limit provided an even greater likelihood of not detecting
E. coli
on carrots (≥1 enrichment-negative result for 100% of the treatments). The rapid maturation of radishes prevented conclusive evaluation of a 100- or 120-day application-to-harvest interval. The absolute absence of
E. coli
from vegetables harvested from manure-fertilized Wisconsin soils may not be ensured solely by adherence to the NOP ≥120-day limit. Unless pathogens are far better at colonizing vegetables than indigenous
E. coli
strains are, it appears that the risk of contamination for vegetables grown in Wisconsin soils would be elevated only slightly by reducing the NOP requirement to ≥100 days.
Survival of
Shewanella oneidensis
MR-1 after UV Radiation Exposure
Authors: Qiu Xiaoyun , Sundin George W. , Chai Benli , Tiedje James M. 
Published: November 2004

ABSTRACT

We systematically investigated the physiological response as well as DNA damage repair and damage tolerance in
Shewanella oneidensis
MR-1 following UVC, UVB, UVA, and solar light exposure. MR-1 showed the highest UVC sensitivity among
Shewanella
strains examined, with D
37
and D
10
values of 5.6 and 16.5% of
Escherichia coli
K-12 values. Stationary cells did not show an increased UVA resistance compared to exponential-phase cells; instead, they were more sensitive at high UVA dose. UVA-irradiated MR-1 survived better on tryptic soy agar than Luria-Bertani plates regardless of the growth stage. A 20% survival rate of MR-1 was observed following doses of 3.3 J of UVC m
−2
, 568 J of UVB m
−2
, 25 kJ of UVA m
−2
, and 558 J of solar UVB m
−2
, respectively. Photoreactivation conferred an increased survival rate to MR-1 of as much as 177- to 365-fold, 11- to 23-fold, and 3- to 10-fold following UVC, UVB, and solar light irradiation, respectively. A significant UV mutability to rifampin resistance was detected in both UVC- and UVB-treated samples, with the mutation frequency in the range of 10
−5
to 10
−6
. Unlike in
E. coli
, the expression levels of the nucleotide excision repair (NER) component genes
uvrA
,
uvrB
, and
uvrD
were not damage inducible in MR-1. Complementation of
Pseudomonas aeruginosa
UA11079 (
uvrA
deficient) with
uvrA
of MR-1 increased the UVC survival of this strain by more than 3 orders of magnitude. Loss of damage inducibility of the NER system appears to contribute to the high sensitivity of this bacterium to UVR as well as to other DNA-damaging agents.
Use of Merocyanine 540 for Photodynamic Inactivation of
Staphylococcus aureus
Planktonic and Biofilm Cells
Authors: Lin Hsiao-Yin , Chen Chin-Tin , Huang Ching-Tsan 
Published: November 2004

ABSTRACT

Photodynamic inactivation of
Staphylococcus aureus
planktonic and biofilm cells by a phtotosensitizer, merocyanine 540 (MC 540), was investigated. For the planktonic experiments, MC 540 binding efficiency to bacterial cells was found to increase with both increasing MC 540 concentration and increasing incubation time, but the binding became saturated following 10 min of incubation. The antimicrobial activity was enhanced with an increasing light dose, but an increase in the light dose could not further improve the antimicrobial activity if the maximum excitation level attainable was less than the necessary minimum threshold level. Complete inactivation was achieved when the excitation level of MC 540 was somewhere above the threshold level. The relationship between antimicrobial activity and the excitation level of MC 540 revealed that the more MC 540 was excited, the more
S. aureus
cells were killed. For the biofilm experiments, the antimicrobial activity was enhanced with an increase in the light dose. No viable cells were detected when organisms were exposed to 15 μg of MC 540 per ml and a light dose of 600 J/cm
2
or to 20 μg of MC 540 per ml and a light dose of 450 J/cm
2
. A quantitative analysis of MC 540 bound to biofilms was also performed, and the images from confocal laser scanning microscopy provided direct evidence that revealed the difference between the MC 540 remaining in the biofilms prior to irradiation and the MC 540 remaining in the biofilms after irradiation. The results of both the planktonic and biofilm experiments suggest that the antimicrobial activity of photodynamic inactivation of
S. aureus
is closely related to the excitation level of MC 540.
Stages of Infection during the Tripartite Interaction between
Xenorhabdus nematophila
, Its Nematode Vector, and Insect Hosts
Authors: Sicard Mathieu , Brugirard-Ricaud Karine , Pagès Sylvie , Lanois Anne , Boemare Noel E. , Brehélin Michel , Givaudan Alain 
Published: November 2004

ABSTRACT

Bacteria of the genus
Xenorhabdus
are mutually associated with entomopathogenic nematodes of the genus
Steinernema
and are pathogenic to a broad spectrum of insects. The nematodes act as vectors, transmitting the bacteria to insect larvae, which die within a few days of infection. We characterized the early stages of bacterial infection in the insects by constructing a constitutive green fluorescent protein (GFP)-labeled
Xenorhabdus nematophila
strain. We injected the GFP-labeled bacteria into insects and monitored infection. We found that the bacteria had an extracellular life cycle in the hemolymph and rapidly colonized the anterior midgut region in
Spodoptera littoralis
larvae. Electron microscopy showed that the bacteria occupied the extracellular matrix of connective tissues within the muscle layers of the
Spodoptera
midgut. We confirmed the existence of such a specific infection site in the natural route of infection by infesting
Spodoptera littoralis
larvae with nematodes harboring GFP-labeled
Xenorhabdus
. When the infective juvenile (IJ) nematodes reached the insect gut, the bacterial cells were rapidly released from the intestinal vesicle into the nematode intestine.
Xenorhabdus
began to escape from the anus of the nematodes when IJs were wedged in the insect intestinal wall toward the insect hemolymph. Following their release into the insect hemocoel, GFP-labeled bacteria were found only in the anterior midgut region and hemolymph of
Spodoptera
larvae. Comparative infection assays conducted with another insect,
Locusta migratoria
, also showed early bacterial colonization of connective tissues. This work shows that the extracellular matrix acts as a particular colonization site for
X. nematophila
within insects.
High-Rate Nitrification at Low pH in Suspended- and Attached-Biomass Reactors
Authors: Tarre Sheldon , Green Michal 
Published: November 2004

ABSTRACT

This article reports on high-rate nitrification at low pH in biofilm and suspended-biomass reactors by known chemolithotrophic bacteria. In the biofilm reactor, at low pH (4.3 ± 0.1) and low bulk ammonium concentrations (9.3 ± 3.3 mg · liter
−1
), a very high nitrification rate of 5.6 g of N oxidized · liter
−1
· day
−1
was achieved. The specific nitrification rate (0.55 g of N · g of biomass
−1
· day
−1
) was similar to values reported for nitrifying reactors at optimal pH. In the suspended-biomass reactor, the average pH was significantly lower than that in the biofilm reactor (pH 3.8 ± 0.3), and values as low as pH 3.2 were found. In addition, measurements in the suspended-biomass reactor, using isotope-labeled ammonium (
15
N), showed that in spite of the very low pH, biomass growth occurred with a yield of 0.1 g of biomass · g of N oxidized
−1
. Fluorescence in situ hybridization using existing rRNA-targeted oligonucleotide probes showed that the nitrifying bacteria were from the monophyletic genus
Nitrosomonas
, suggesting that autotrophic nitrification at low pH is more widespread than previously thought. The results presented in this paper clearly show that autotrophic nitrifying bacteria have the ability to nitrify at a high rate at low pH and in the presence of only a negligible free ammonia concentration, suggesting the presence of an efficient ammonium uptake system and the means to cope with low pH.
Identification of a Third
msa
Gene in
Renibacterium salmoninarum
and the Associated Virulence Phenotype
Authors: Rhodes Linda D. , Coady Alison M. , Deinhard Rebecca K. 
Published: November 2004

ABSTRACT

Renibacterium salmoninarum
, a gram-positive diplococcobacillus, causes bacterial kidney disease, a condition that can result in extensive morbidity and mortality among stocks of fish. An immunodominant extracellular protein, called major soluble antigen (MSA), is encoded by two identical genes,
msa1
and
msa2
. We found evidence for a third
msa
gene,
msa3
, which appears to be a duplication of
msa1
. Unlike
msa1
and
msa2
,
msa3
is not present in all isolates of
R. salmoninarum
. The presence of the
msa3
locus does not affect total MSA production in culture conditions. In a challenge study, isolates possessing the
msa3
locus reduced median survival in juvenile chinook salmon (
Oncorhynchus tshawytscha
) by an average of 34% at doses of ≤10
5
cells per fish compared to isolates lacking the
msa3
locus. In contrast, no difference in survival was observed at the highest dose, 10
6
cells per fish. The phenotype associated with the
msa3
locus and its nonuniform distribution may contribute to observed differences in virulence among
R. salmoninarum
isolates.
Transport of the Harmful Bloom Alga
Aureococcus anophagefferens
by Oceangoing Ships and Coastal Boats
Authors: Doblin Martina A. , Popels Linda C. , Coyne Kathryn J. , Hutchins David A. , Cary S. Craig , Dobbs Fred C. 
Published: November 2004

ABSTRACT

It is well established that cyst-forming phytoplankton species are transported in ships' ballast tanks. However, there is increasing evidence that other phytoplankton species which do not encyst are also capable of surviving ballast transit. These species have alternative modes of nutrition (hetero- or mixotrophy) and/or are able to survive long-term darkness. In our studies of no-ballast-on-board vessels arriving in the Great Lakes, we tested for the presence of the harmful algal bloom species
Aureococcus anophagefferens
(brown tide) in residual (i.e., unpumpable) ballast water using methods based on the PCR. During 2001, the brown tide organism was detected in 7 of 18 ballast water tanks in commercial ships following transit from foreign ports. Furthermore, it was detected after 10 days of ballast tank confinement during a vessel transit in the Great Lakes, a significant result given the large disparity between the salinity tolerance for active growth of
Aureococcus
(>22 ppt) and the low salinity of the residual ballast water (∼2 ppt). We also investigated the potential for smaller, recreational vessels to transport and distribute
Aureococcus
. During the summer of 2002, 11 trailered boats from the inland bays of Delaware and coastal bays of Maryland were sampled. Brown tide was detected in the bilge water in the bottoms of eight boats, as well as in one live-well sample. Commercial ships and small recreational boats are therefore implicated as potential vectors for long-distance transport and local-scale dispersal of
Aureococcus
.
Coupling of Functional Gene Diversity and Geochemical Data from Environmental Samples
Authors: Palumbo A. V. , Schryver J. C. , Fields M. W. , Bagwell C. E. , Zhou J.-Z. , Yan T. , Liu X. , Brandt C. C. 
Published: November 2004

ABSTRACTGenomic techniques commonly used for assessing distributions of microorganisms in the environment often produce small sample sizes. We investigated artificial neural networks for analyzing the distributions of nitrite reductase genes (nirSandnirK) and two sets of dissimilatory sulfite reductase genes (dsrAB1anddsrAB2) in small sample sets. Data reduction (to reduce the number of input parameters), cross-validation (to measure the generalization error), weight decay (to adjust model parameters to reduce generalization error), and importance analysis (to determine which variables had the most influence) were useful in developing and interpreting neural network models that could be used to infer relationships between geochemistry and gene distributions. A robust relationship was observed between geochemistry and the frequencies of genes that were not closely related to known dissimilatory sulfite reductase genes (dsrAB2). Uranium and sulfate appeared to be the most related to distribution of two groups of these unusualdsrAB-related genes. For the other three groups, the distributions appeared to be related to pH, nickel, nonpurgeable organic carbon, and total organic carbon. The models relating the geochemical parameters to the distributions of thenirS,nirK, anddsrAB1genes did not generalize as well as the models fordsrAB2. The data also illustrate the danger (generating a model that has a high generalization error) of not using a validation approach in evaluating the meaningfulness of the fit of linear or nonlinear models to such small sample sizes.
Bacterium-Based NO
2
−
Biosensor for Environmental Applications
Authors: Nielsen Michael , Larsen Lars Hauer , Jetten Mike S. M. , Revsbech Niels Peter 
Published: November 2004

ABSTRACT

A sensitive NO
2
−
biosensor that is based on bacterial reduction of NO
2
−
to N
2
O and subsequent detection of the N
2
O by a built-in electrochemical N
2
O sensor was developed. Four different denitrifying organisms lacking NO
3
−
reductase activity were assessed for use in the biosensor. The relevant physiological aspects examined included denitrifying characteristics, growth rate, NO
2
−
tolerance, and temperature and salinity effects on the growth rate. Two organisms were successfully used in the biosensor. The preferred organism was
Stenotrophomonas nitritireducens
, which is an organism with a denitrifying pathway deficient in both NO
3
−
and N
2
O reductases. Alternatively
Alcaligenes faecalis
could be used when acetylene was added to inhibit its N
2
O reductase. The macroscale biosensors constructed exhibited a linear NO
2
−
response at concentrations up to 1 to 2 mM. The detection limit was around 1 μM NO
2
−
, and the 90% response time was 0.5 to 3 min. The sensor signal was specific for NO
2
−
, and interference was observed only with NH
2
OH, NO, N
2
O, and H
2
S. The sensor signal was affected by changes in temperature and salinity, and calibration had to be performed in a system with a temperature and an ionic strength comparable to those of the medium analyzed. A broad range of water bodies could be analyzed with the biosensor, including freshwater systems, marine systems, and oxic-anoxic wastewaters. The NO
2
−
biosensor was successfully used for long-term online monitoring in wastewater. Microscale versions of the NO
2
−
biosensor were constructed and used to measure NO
2
−
profiles in marine sediment.
Diversity and Antagonistic Potential of Bacteria Associated with Bryophytes from Nutrient-Poor Habitats of the Baltic Sea Coast
Authors: Opelt Katja , Berg Gabriele 
Published: November 2004

ABSTRACT

Very little is known about the interaction of bryophytes with bacteria. Therefore, we analyzed bacteria associated with three bryophyte species,
Tortula ruralis
,
Aulacomnium palustre
, and
Sphagnum rubellum
, which represent typical moss species of three nutrient-poor plant communities at the southern Baltic Sea coast in Germany. By use of two cultivation-independent techniques, denaturing gradient gel electrophoresis and single-strand conformation polymorphism analysis of the 16S ribosomal DNA, a high degree of moss specificity was found for associated bacterial communities. This specificity could be further evidenced by a cultivation-dependent approach for the following parameters: (i) plate counts of bacteria on R2A medium, (ii) proportion of antagonistic isolates, (iii) antagonistic activity as well as spectrum against pathogens, and (iv) diversity and richness of antagonistic isolates. The proportion of isolates with antagonistic activity against the pathogenic model fungus
Verticillium dahliae
was highest for
S. rubellum
(31%), followed by
A. palustre
(17%) and
T. ruralis
(5%). A high percentage (99%) of moss-associated antagonistic bacteria produced antifungal compounds. The high recovery of antagonistic isolates strongly suggests that bryophytes represent an ecological niche which harbors a diverse and hitherto largely uncharacterized microbial population with yet unknown and untapped potential biotechnological applications, e.g., for biological control of plant pathogens.
Display of Biologically Functional Insecticidal Toxin on the Surface of λ Phage
Authors: Vílchez Susana , Jacoby Juliette , Ellar David J. 
Published: November 2004

ABSTRACT

The successful use of
Bacillus thuringiensis
insecticidal toxins to control agricultural pests could be undermined by the evolution of insect resistance. Under selection pressure in the laboratory, a number of insects have gained resistance to the toxins, and several cases of resistance in the diamondback moth have been reported from the field. The use of protein engineering to develop novel toxins active against resistant insects could offer a solution to this problem. The display of proteins on the surface of phages has been shown to be a powerful technology to search for proteins with new characteristics from combinatorial libraries. However, this potential of phage display to develop Cry toxins with new binding properties and new target specificities has hitherto not been realized because of the failure of displayed Cry toxins to bind their natural receptors. In this work we describe the construction of a display system in which the Cry1Ac toxin is fused to the amino terminus of the capsid protein D of bacteriophage lambda. The resultant phage was viable and infectious, and the displayed toxin interacted successfully with its natural receptor.
Effects of the Metalloid Oxyanion Tellurite (TeO
3
2−
) on Growth Characteristics of the Phototrophic Bacterium
Rhodobacter capsulatus
Authors: Borghese Roberto , Borsetti Francesca , Foladori Paola , Ziglio Giuliano , Zannoni Davide 
Published: November 2004

ABSTRACT

This work examines the effects of potassium tellurite (K
2
TeO
3
) on the cell viability of the facultative phototroph
Rhodobacter capsulatus
. There was a growth mode-dependent response in which cultures anaerobically grown in the light tolerate the presence of up to 250 to 300 μg of tellurite (TeO
3
2−
) per ml, while dark-grown aerobic cells were inhibited at tellurite levels as low as 2 μg/ml. The tellurite sensitivity of aerobic cultures was evident only for growth on minimal salt medium, whereas it was not seen during growth on complex medium. Notably, through the use of flow cytometry, we show that the cell membrane integrity was strongly affected by tellurite during the early growth phase (≤50% viable cells); however, at the end of the growth period and in parallel with massive tellurite intracellular accumulation as elemental Te
0
crystallites, recovery of cytoplasmic membrane integrity was apparent (≥90% viable cells), which was supported by the development of a significant membrane potential (Δψ = 120 mV). These data are taken as evidence that in anaerobic aquatic habitats, the facultative phototroph
R. capsulatus
might act as a natural scavenger of the highly soluble and toxic oxyanion tellurite.