bluuebunny/crossref_metadata_2025_split huggingface dataset:
ACEI of
Trichoderma reesei
Is a Repressor of Cellulase and Xylanase Expression
Authors: Aro Nina , Ilmén Marja , Saloheimo Anu , Penttilä Merja 
Published: January 2003

ABSTRACT

We characterized the effect of deletion of the
Trichoderma reesei
(
Hypocrea jecorina
)
ace1
gene encoding the novel cellulase regulator ACEI that was isolated based on its ability to bind to and activate in vivo in
Saccharomyces cerevisiae
the promoter of the main cellulase gene,
cbh1
. Deletion of
ace1
resulted in an increase in the expression of all the main cellulase genes and two xylanase genes in sophorose- and cellulose-induced cultures, indicating that ACEI acts as a repressor of cellulase and xylanase expression. Growth of the strain with a deletion of the
ace1
gene on different carbon sources was analyzed. On cellulose-based medium, on which cellulases are needed for growth, the Δ
ace1
strain grew better than the host strain due to the increased cellulase production. On culture media containing sorbitol as the sole carbon source, the growth of the strain with a deletion of the
ace1
gene was severely impaired, suggesting that ACEI regulates expression of other genes in addition to cellulase and xylanase genes. A strain with a deletion of the
ace1
gene and with a deletion of the
ace2
gene coding for the cellulase and xylanase activator ACEII expressed cellulases and xylanases similar to the Δ
ace1
strain, indicating that yet another activator regulating cellulase and xylanase promoters was present.
Acetic Acid Increases Stability of Silage under Aerobic Conditions
Authors: Danner H. , Holzer M. , Mayrhuber E. , Braun R. 
Published: January 2003

ABSTRACTThe effects of various compounds on the aerobic stability of silages were evaluated. It has been observed that inoculation of whole-crop maize with homofermentative lactic acid bacteria leads to silages which have low stability against aerobic deterioration, while inoculation with heterofermentative lactic acid bacteria, such asLactobacillus brevisorLactobacillus buchneri, increases stability. Acetic acid has been proven to be the sole substance responsible for the increased aerobic stability, and this acid acts as an inhibitor of spoilage organisms. Therefore, stability increases exponentially with acetic acid concentration. Only butyric acid has a similar effect. Other compounds, like lactic acid, 1,2-propanediol, and 1-propanol, have been shown to have no effect, while fructose and mannitol reduce stability.
2-
n
-Pentyl-4-Quinolinol Produced by a Marine
Alteromonas
sp. and Its Potential Ecological and Biogeochemical Roles
Authors: Long Richard A. , Qureshi Asfia , Faulkner D. John , Azam Farooq 
Published: January 2003

ABSTRACT

Bacterium-bacterium interactions occur at intimate spatial scales on the order of micrometers, but our knowledge of interactions at this level is rudimentary. Antagonism is a potential interaction in such microenvironments. To study the ecological role of antibiosis, we developed a model system involving an antibiotic-producing isolate (SWAT5) derived from a marine particle and its dominant antibiotic product, 2-
n
-pentyl-4-quinolinol (PQ). This system was used to address questions about the significance of this antibiotic for microbial ecology and carbon cycling on particles. We characterized the chemical and inhibitory properties of PQ in relation to the mechanisms used by particle-associated bacteria in interacting with particles and with other attached bacteria. PQ was produced by SWAT5 only on surfaces. When SWAT5 was grown in polysaccharide matrices, PQ diffused within the matrices but not into the surrounding seawater. SWAT5 might thus be able to generate a localized zone of high antibiotic concentration on particles suspended or sinking through seawater. Target bacterial respiration was most sensitive to PQ (75 nM), while inhibition of DNA synthesis, protein synthesis, and bacterial motility required higher (micromolar) PQ levels. The presence of PQ altered the composition of the bacterial community that colonized and developed in a model particle system. PQ also inhibited
Synechococcus
and phytoplankton growth. Our results suggest that antibiosis may significantly influence community composition and activities of attached bacterial and thus regulate the biogeochemical fate of particulate organic matter in the ocean.
Inactivation of Feline Calicivirus and Adenovirus Type 40 by UV Radiation
Authors: Thurston-Enriquez Jeanette A. , Haas Charles N. , Jacangelo Joseph , Riley Kelley , Gerba Charles P. 
Published: January 2003

ABSTRACT

Little information regarding the effectiveness of UV radiation on the inactivation of caliciviruses and enteric adenoviruses is available. Analysis of human calicivirus resistance to disinfectants is hampered by the lack of animal or cell culture methods that can determine the viruses' infectivity. The inactivation kinetics of enteric adenovirus type 40 (AD40), coliphage MS-2, and feline calicivirus (FCV), closely related to the human caliciviruses based on nucleic acid organization and capsid architecture, were determined after exposure to low-pressure UV radiation in buffered demand-free (BDF) water at room temperature. In addition, UV disinfection experiments were also carried out in treated groundwater with FCV and AD40. AD40 was more resistant than either FCV or coliphage MS-2 in both BDF water and groundwater. The doses of UV required to achieve 99% inactivation of AD40, coliphage MS-2, and FCV in BDF water were 109, 55, and 16 mJ/cm
2
, respectively. The doses of UV required to achieve 99% inactivation of AD40, coliphage MS-2, and FCV in groundwater were slightly lower than those in BDF water. FCV was inactivated by 99% by 13 mJ/cm
2
in treated groundwater. A dose of 103 mJ/cm
2
was required for 99% inactivation of AD40 in treated groundwater. The results of this study indicate that if FCV is an adequate surrogate for human caliciviruses, then their inactivation by UV radiation is similar to those of other single-stranded RNA enteric viruses, such as poliovirus. In addition, AD40 appears to be more resistant to UV disinfection than previously reported.
Influences of Pond Geochemistry, Temperature, and Freeze-Thaw on Terminal Anaerobic Processes Occurring in Sediments of Six Ponds of the McMurdo Ice Shelf, near Bratina Island, Antarctica
Authors: Mountfort Douglas O. , Kaspar Heinrich F. , Asher Rodney A. , Sutherland Donna 
Published: January 2003

ABSTRACT

The effects of freeze-thaw, freezing and sediment geochemistry on terminal anaerobic processes occurring in sediments taken from below cyanobacterial mats in meltwater ponds of the McMurdo Ice Shelf in Antarctica were investigated. Depending on the geochemical and physical status of the sediments (i.e., frozen or thawed), as well as passage of sediment through a freeze-thaw cycle, terminal carbon and electron flow shifted in which the proportions of hydrogen and acetate utilized for methanogenesis and sulfate reduction changed. Thus, in low-sulfate (or chloride) sediment which was thawed and incubated at 4°C, total carbon and electron flow were mediated by acetate-driven sulfate reduction and H
2
-driven methanogenesis. When the same sediments were incubated frozen, both methanogenesis and sulfate reduction decreased. However, under these conditions methanogenesis was favored over sulfate reduction, and carbon flow from acetate to methane increased relative to sulfate reduction; >70% of methane was contributed by acetate, and more than 80% of acetate was oxidized by pathways not coupled to sulfate reduction. In high-sulfate pond sediments, sulfate reduction was a major process mediating terminal carbon and electron flow in both unfrozen and frozen incubations. However, as with low-sulfate sediments, acetate oxidation became uncoupled from sulfate reduction with freezing. Geochemical and temperature effects could be expressed by linear models in which the log (methanogenesis to sulfate reduction) was negative log linear with respect to either temperature or the log of the sulfate (or chloride) concentration. From these relationships it was possible to predict the ratio for a given temperature (low-sulfate sediments) or sulfate (chloride) concentration. Small transitory changes, such as elevated sulfate reduction coupled to increased acetate turnover, resulted from application of a freeze-thaw cycle to low-salinity pond sediments. The results demonstrate how ecophysiological processes may change in anaerobic systems under extreme conditions (e.g., freezing) and provide new insights into microbial events occurring under these conditions.
A Field Investigation of
Bacillus anthracis
Contamination of U.S. Department of Agriculture and Other Washington, D.C., Buildings during the Anthrax Attack of October 2001
Authors: Higgins James A. , Cooper Mary , Schroeder-Tucker Linda , Black Scott , Miller David , Karns Jeffrey S. , Manthey Erlynn , Breeze Roger , Perdue Michael L. 
Published: January 2003

ABSTRACT

In response to a bioterrorism attack in the Washington, D.C., area in October 2001, a mobile laboratory (ML) was set up in the city to conduct rapid molecular tests on environmental samples for the presence of
Bacillus anthracis
spores and to route samples for further culture analysis. The ML contained class I laminar-flow hoods, a portable autoclave, two portable real-time PCR devices (Ruggedized Advanced Pathogen Identification Device [RAPID]), and miscellaneous supplies and equipment to process samples. Envelopes and swab and air samples collected from 30 locations in the metropolitan area once every three days were subjected to visual examination and DNA extraction, followed by real-time PCR using freeze-dried, fluorescent-probe-based reagents. Surface swabs and air samples were also cultured for
B. anthracis
at the National Veterinary Service Laboratory (NVSL) in Ames, Iowa. From 24 October 2001 to 15 September 2002, 2,092 pieces of mail were examined, 405 real-time PCR assays were performed (comprising 4,639 samples), and at the NVSL 6,275 samples were subjected to over 18,000 platings. None of the PCR assays on DNA extracted from swab and air samples were positive, but viable spores were cultured from surface swabs taken from six locations in the metropolitan area in October, November, and December 2001 and February, March, and May 2002. DNA extracted from these suspected
B. anthracis
colonies was positive by real-time and conventional PCRs for the lethal factor, pXO1, and for
capA
and
vrr
genes; sequence analysis of the latter amplicons indicated >99% homology with the Ames, vollum, B6273-93, C93022281, and W-21 strains of
B. anthracis
, suggesting they arose from cross-contamination during the attack through the mail. The RAPID-based PCR analysis provided fast confirmation of suspect colonies from an overnight incubation on agar plates.
Survival and Growth ofFrancisella tularensisinAcanthamoeba castellanii
Authors: Abd Hadi , Johansson Thorsten , Golovliov Igor , Sandström Gunnar , Forsman Mats 
Published: January 2003

ABSTRACTFrancisella tularensisis a highly infectious, facultative intracellular bacterium which causes epidemics of tularemia in both humans and mammals at regular intervals. The natural reservoir of the bacterium is largely unknown, although it has been speculated that protozoa may harbor it. To test this hypothesis,Acanthamoeba castellaniiwas cocultured with a strain ofF. tularensisengineered to produce green fluorescent protein (GFP) in a nutrient-rich medium. GFP fluorescence withinA. castellaniiwas then monitored by flow cytometry and fluorescence microscopy. In addition, extracellular bacteria were distinguished from intracellular bacteria by targeting with monoclonal antibodies. Electron microscopy was used to determine the intracellular location ofF. tularensisinA. castellanii, and viable counts were obtained for both extracellular and intracellular bacteria. The results showed that manyF. tularensiscells were located intracellularly inA. castellaniicells. The bacteria multiplied within intracellular vacuoles and eventually killed many of the host cells.F. tularensiswas found in intact trophozoites, excreted vesicles, and cysts. Furthermore,F. tularensisgrew faster in cocultures withA. castellaniithan it did when grown alone in the same medium. This increase in growth was accompanied by a decrease in the number ofA. castellaniicells. The interaction betweenF. tularensisand amoebae demonstrated in this study indicates that ubiquitous protozoa might be an important environmental reservoir forF. tularensis.
Bacteria Associated with Cysts of the Soybean Cyst Nematode (
Heterodera glycines
)
Authors: Nour Sarah M. , Lawrence John R. , Zhu Hong , Swerhone George D. W. , Welsh Martha , Welacky Tom W. , Topp Edward 
Published: January 2003

ABSTRACT

The soybean cyst nematode (SCN),
Heterodera glycines
, causes economically significant damage to soybeans (
Glycine max
) in many parts of the world. The cysts of this nematode can remain quiescent in soils for many years as a reservoir of infection for future crops. To investigate bacterial communities associated with SCN cysts, cysts were obtained from eight SCN-infested farms in southern Ontario, Canada, and analyzed by culture-dependent and -independent means. Confocal laser scanning microscopy observations of cyst contents revealed a microbial flora located on the cyst exterior, within a polymer plug region and within the cyst. Microscopic counts using 5-(4,6-dichlorotriazine-2-yl)aminofluorescein staining and in situ hybridization (EUB 338) indicated that the cysts contained (2.6 ± 0.5) × 10
5
bacteria (mean ± standard deviation) with various cellular morphologies. Filamentous fungi were also observed. Live-dead staining indicated that the majority of cyst bacteria were viable. The probe Nile red also bound to the interior polymer, indicating that it is lipid rich in nature. Bacterial community profiles determined by denaturing gradient gel electrophoresis analysis were simple in composition. Bands shared by all eight samples included the actinobacterium genera
Actinomadura
and
Streptomyces
. A collection of 290 bacteria were obtained by plating macerated surface-sterilized cysts onto nutrient broth yeast extract agar or on actinomycete medium. These were clustered into groups of siblings by repetitive extragenic palindromic PCR fingerprinting, and representative isolates were tentatively identified on the basis of 16S rRNA gene sequence. Thirty phylotypes were detected, with the collection dominated by
Lysobacter
and
Variovorax
spp. This study has revealed the cysts of this important plant pathogen to be rich in a variety of bacteria, some of which could presumably play a role in the ecology of SCN or have potential as biocontrol agents.
Genetic Diversity of Isolates of
Glomus mosseae
from Different Geographic Areas Detected by Vegetative Compatibility Testing and Biochemical and Molecular Analysis
Authors: Giovannetti Manuela , Sbrana Cristiana , Strani Patrizia , Agnolucci Monica , Rinaudo Valeria , Avio Luciano 
Published: January 2003

ABSTRACT

We detected, for the first time, the occurrence of vegetative incompatibility between different isolates of the arbuscular mycorrhizal fungal species
Glomus mosseae
. Vegetative compatibility tests performed on germlings belonging to the same isolate showed that six geographically different isolates were capable of self-anastomosing, and that the percentage of hyphal contacts leading to fusions ranged from 60 to 85%. Successful anastomoses were characterized by complete fusion of hyphal walls, protoplasm continuity and occurrence of nuclei in the middle of hyphal bridges. No anastomoses could be detected between hyphae belonging to different isolates, which intersected without any reaction in 49 to 68% of contacts. Microscopic examinations detected hyphal incompatibility responses in diverse pairings, consisting of protoplasm retraction from the tips and septum formation in the approaching hyphae, even before physical contact with neighboring hyphae. Interestingly, many hyphal tips showed precontact tropism, suggesting that specific recognition signals may be involved during this stage. The intraspecific genetic diversity of
G. mosseae
revealed by vegetative compatibility tests was confirmed by total protein profiles and internal transcribed spacer-restriction fragment length polymorphism profiles, which evidenced a higher level of molecular diversity between the two European isolates IMA1 and BEG25 than between IMA1 and the two American isolates. Since arbuscular mycorrhizal fungi lack a tractable genetic system, vegetative compatibility tests may represent an easy assay for the detection of genetically different mycelia and an additional powerful tool for investigating the population structure and genetics of these obligate symbionts.
Phylogenetic Position and In Situ Identification of Ectosymbiotic Spirochetes on Protists in the Termite Gut
Authors: Noda Satoko , Ohkuma Moriya , Yamada Akinori , Hongoh Yuichi , Kudo Toshiaki 
Published: January 2003

ABSTRACT

Phylogenetic relationships, diversity, and in situ identification of spirochetes in the gut of the termite
Neotermes koshunensis
were examined without cultivation, with an emphasis on ectosymbionts attached to flagellated protists. Spirochetes in the gut microbial community investigated so far are related to the genus
Treponema
and divided into two phylogenetic clusters. In situ hybridizations with a 16S rRNA-targeting consensus oligonucleotide probe for one cluster (known as termite
Treponema
cluster I) detected both the ectosymbiotic spirochetes on gut protists and the free-swimming spirochetes in the gut fluid of
N. koshunensis
. The probe for the other cluster (cluster II), which has been identified as ectosymbionts on gut protists of two other termite species,
Reticulitermes speratus
and
Hodotermopsis sjoestedti
, failed to detect any spirochete population. The absence of cluster II spirochetes in
N. koshunensis
was confirmed by intensive 16S ribosomal DNA (rDNA) clone analysis, in which remarkably diverse spirochetes of 45 phylotypes were identified, almost all belonging to cluster I. Ectosymbiotic spirochetes of the three gut protist species
Devescovina
sp.,
Stephanonympha
sp., and
Oxymonas
sp. in
N. koshunensis
were identified by their 16S rDNA and by in situ hybridizations using specific probes. The probes specific for these ectosymbionts did not receive a signal from the free-swimming spirochetes. The ectosymbionts were dispersed in cluster I of the phylogeny, and they formed distinct phylogenetic lineages, suggesting multiple origins of the spirochete attachment. Each single protist cell harbored multiple spirochete species, and some of the spirochetes were common among protist species. The results indicate complex relationships of the ectosymbiotic spirochetes with the gut protists.
Antifungal Activity of Phenyllactic Acid against Molds Isolated from Bakery Products
Authors: Lavermicocca Paola , Valerio Francesca , Visconti Angelo 
Published: January 2003

ABSTRACT

Phenyllactic acid (PLA) has recently been found in cultures of
Lactobacillus plantarum
that show antifungal activity in sourdough breads. The fungicidal activity of PLA and growth inhibition by PLA were evaluated by using a microdilution test and 23 fungal strains belonging to 14 species of
Aspergillus
,
Penicillium
, and
Fusarium
that were isolated from bakery products, flours, or cereals. Less than 7.5 mg of PLA ml
−1
was required to obtain 90% growth inhibition for all strains, while fungicidal activity against 19 strains was shown by PLA at levels of ≤10 mg ml
−1
. Levels of growth inhibition of 50 to 92.4% were observed for all fungal strains after incubation for 3 days in the presence of 7.5 mg of PLA ml
−1
in buffered medium at pH 4, which is a condition more similar to those in real food systems. Under these experimental conditions PLA caused an unpredictable delaying effect that was more than 2 days long for 12 strains, including some mycotoxigenic strains of
Penicillium verrucosum
and
Penicillium citrinum
and a strain of
Penicillium roqueforti
(the most widespread contaminant of bakery products); a growth delay of about 2 days was observed for seven other strains. The effect of pH on the inhibitory activity of PLA and the combined effects of the major organic acids produced by lactic acid bacteria isolated from sourdough bread (PLA, lactic acid, and acetic acid) were also investigated. The ability of PLA to act as a fungicide and delay the growth of a variety of fungal contaminants provides new perspectives for possibly using this natural antimicrobial compound to control fungal contaminants and extend the shelf lives of foods and/or feedstuffs.
Evaluation of the Redox Dye 5-Cyano-2,3-Tolyl-Tetrazolium Chloride for Activity Studies by Simultaneous Use of Microautoradiography and Fluorescence In Situ Hybridization
Authors: Nielsen Jeppe Lund , Aquino de Muro Marilena , Nielsen Per Halkjær 
Published: January 2003

ABSTRACT

Three microscopic in situ techniques were used simultaneously to investigate viability and activity on a single-cell level in activated sludge. The redox dye 5-cyano-2,3-tolyl-tetrazolium chloride (CTC) was compared with microautoradiography (MAR) and fluorescence in situ hybridization (FISH) to indicate activity of cells in
Thiothrix
filaments and in single floc-forming bacteria. The signals from MAR and FISH correlated well, whereas only 65% of the active
Thiothrix
cells and 41% of all single cells were detectable by CTC reduction, which mainly targeted the most active cells.
Distribution of Microorganisms in the Subsurface of the Manus Basin Hydrothermal Vent Field in Papua New Guinea
Authors: Kimura Hiroyuki , Asada Ryuji , Masta Andrew , Naganuma Takeshi 
Published: January 2003

ABSTRACT

The distribution of microorganisms in the subsurfaces of hydrothermal vents was investigated by using subvent rock core samples. Microbial cells and ATP were detected from cores taken at depths of less than 99.4 and 44.8 m below the seafloor (mbsf), respectively. Cores from various depths were incubated anaerobically with a heterotrophic medium. Growth at 60 and 90°C was ascribed to a
Geobacillus
sp. in the 448.6- to 99.4-mbsf cores and a
Deinococcus
sp. in the 64.8- to 128.9-mbsf cores, respectively, based on the 16S ribosomal DNA analysis.
The Spoilage Yeast
Zygosaccharomyces bailii
Forms Mitotic Spores: a Screening Method for Haploidization
Authors: Rodrigues Fernando , Ludovico Paula , Sousa Maria João , Steensma H. Yde , Côrte-Real Manuela , Leão Cecília 
Published: January 2003

ABSTRACT

Zygosaccharomyces bailii
ISA 1307 and the type strain of this spoilage yeast show a diploid DNA content. Together with a rather peculiar life cycle in which mitotic but no meiotic spores appear to be formed, the diploid DNA content explains the observed difficulties in obtaining auxotrophic mutants. Mitotic chromosome loss induced by benomyl and selection on canavanine media resulted in three haploid strains of
Z. bailii
. This new set of
Z. bailii
strains allows the easy isolation of recessive mutants and is suitable for further molecular genetic studies.
Enumeration of Bifidobacteria in Gastrointestinal Samples from Piglets
Authors: Mikkelsen Lene Lind , Bendixen Christian , Jakobsen Mogens , Jensen Bent Borg 
Published: January 2003

ABSTRACT

The population of
Bifidobacterium
spp. in fecal samples from suckling piglets was investigated, and Beerens, raffinose-bifidobacterium (RB), and modified Wilkins-Chalgren (MW) agar media were evaluated with regard to the enumeration of bifidobacteria in porcine intestinal samples. The results demonstrated that the population of bifidobacteria in the feces of suckling piglets is numerically low, and a phylogenetic analysis of the 16S rRNA gene from bifidobacterial isolates suggested that a possibly new
Bifidobacterium
species was isolated. Beerens, RB, and MW agar media were not selective for bifidobacteria in the fecal samples. The highest recovery and diversity of bifidobacteria were obtained for MW agar. Nonbifidobacterial isolates from the three agar media were identified and may contribute to the future formulation of improved selective media for the enumeration of bifidobacteria.