bluuebunny/crossref_metadata_2025 huggingface dataset:
Strategic Management of an Invasive Ant‐scale Mutualism Enables Recovery of a Threatened Tropical Tree Species
Authors: Gaigher Rene , Samways Michael J.
Published: June 2012

Mutualisms between invasive ants and honeydew‐producing insects can have widespread negative effects on natural ecosystems. This is becoming an increasingly serious problem worldwide, causing certain ecosystems to change radically. Management of these abundant and influential mutualistic species is essential if the host ecosystem is to recover to its former non‐invaded status. This negative effect is particularly prevalent on some tropical islands, including Cousine Island, Seychelles. On this island, the invasive ant
Pheidole megacephala has caused serious indirect damage to the threatened native
Pisonia grandis trees via a mutualism with an invasive scale insect,
Pulvinaria urbicola. We aimed to suppress the ant, thereby decoupling the mutualism and enabling recovery of the
Pisonia trees. We treated all areas where ant pressure was high with a selective formicidal bait, which was deployed in custom‐made bait stations designed to avoid risk of treatment to endemic fauna. In the treated area, ant foraging activity was reduced by 93 percent and was followed by a 100 percent reduction in scale insect density. Abundance of endemic herbivorous insects and herbivorous activity increased significantly, however, after the decline in mutualistic species densities. Despite the native herbivore increase, there was considerable overall improvement in
Pisonia shoot condition and an observed increase in foliage density. Our results demonstrate the benefit of strategic management of highly mutualistic alien species to the native
Pisonia trees. It also supports the idea that area‐wide suppression is a feasible alternative to eradication for achieving positive conservation management at the level of the forest ecosystem.
QUALITY OF RAW CHICKEN BREAST STORED AT 5C AND PACKAGED UNDER DIFFERENT MODIFIED ATMOSPHERES
Authors: CORTEZ‐VEGA W.R. , PIZATO S. , PRENTICE C.
Published: July 2012

The objective of this study was to determine the quality of raw chicken breast store at 5C and packaged under different modified atmospheres. The samples of raw chicken breast (20 samples per treatment) were individually wrapped and packed in high‐density plastic bags. Before sealing, the air was removed automatically by an air removal system (vacuum) and then injected into different mixtures of purified natural gas. Physicochemical analysis of texture, pH, thiobarbituric acid (TBA), total volatile bases (TVB), color and microbiological analyses (mesophilic aerobic, Staphylococcus, psychrotrophic, Salmonella and Escherichia coli) were carried out. The cutting strengths and TBA of the control sample after 9 days of storage were 0.94 kgf and 0.601, respectively, there was lower browning, variation in pH, TBA and nitrogen TVB, and a lower growth of psychrotrophic, mesophilic and Staphylococcus was shown; the absence of Salmonella and Escherichia coli is noted. It can be concluded that the best treatment is C after 9 days of storage obtaining a longer shelf life of the chicken breast meat.

PRACTICAL APPLICATIONS

The deterioration of foods caused by internal and external factors are responsible for considerable economic loss. Chicken breast meat is easily perishable by microorganisms depending on conditions of supply and production chain. An alternative to try to minimize the losses and increase the shelf life of this product is the use of modified atmospheres. The use of modified atmospheres in this study was effective to retard spoilage and reduce the volatile compounds in chicken breast meat, thus increasing food security without bringing risk to public health.
NAD(P)H oxidase p22phox polymorphism and cardiovascular function in amateur runners
Authors: Gallina S. , Di Francescomarino S. , Di Mauro M. , Izzicupo P. , D'Angelo E. , D'Amico M.A. , Pennelli A. , Amicarelli F. , Di Baldassarre A.
Published: June 2012

Aim

NAD(P)H system represents the major source of superoxide production at cardiovascular (CV) level. It has several genetic variants: in particular, the C242T polymorphism of its p22phox subunit is associated with a different oxidase activity, being the T allele related to a lower superoxide production. Although several authors investigated the protective effect of T allele in CV diseases, only few data are available on its functional role in physiological conditions. The aim of our study was to investigate the relationship between the p22phox C242T polymorphism and CV function in amateur runners.

Methods

Seventy‐three male amateur runners were screened for CYBA polymorphism. CV analysis was performed by echocardiographic‐Doppler examination and by PulsePen tonometer assessment.

Results

The genetic subgroups (CC and CT/TT) did not differ for
VM
O2max and cardiac dimension. Nevertheless, T carriers (n = 40) were characterized by a more efficient myocardial contraction and left ventricular (LV) filling, as evidenced by significant higher values of the midwall fractional shortening, systolic excursion of the tricuspid annular plane and of early/late diastolic wave velocities ratio and by a lower E wave deceleration time. Pulse wave velocity and augmentation index, parameters related to the arterial stiffness, were higher in CC subjects compared with CT/TT also when the analysis was adjusted for weight and diastolic pressure.

Conclusion

In amateur runners, CYBA variants may influence both systolic and diastolic function and arterial stiffness. We suppose that the lower oxidative activity that characterizes 242T subjects may positively influence the excitation–contraction and arterial–ventricular coupling mechanisms, thus leading to a more efficient CV function.
Health Benefits, Enzymatic Production, and Application of Medium‐ and Long‐Chain Triacylglycerol (MLCT) in Food Industries: A Review
Authors: Lee Yee‐Ying , Tang Teck‐Kim , Lai Oi‐Ming
Published: July 2012

Abstract:  Medium‐ and long‐chain triacylglycerol (MLCT) is a modified lipid containing medium‐ chain (C6‐C12) and long‐chain fatty acids (C14‐C24) in the same triacylglycerol (TAG) molecule. It can be produced either through enzymatic (with 1,3 specific or nonspecific enzyme) or chemical methods. The specialty of this structured lipid is that it is metabolized differently compared to conventional fats and oils, which can lead to a reduction of fat accumulation in the body. Therefore, it can be used for obesity management. It also contains nutritional properties that can be used to treat metabolic problems. This review will discuss on the health benefits of MLCT, its production methods especially via enzymatic processes and its applications in food industries.
Computed tomography evaluation of craniofacial fibrous dysplasia in an African population
Authors: Ogbole G.I. , Akinmoladun V.I.
Published: July 2012

Aim:  Fibrous dysplasia is a benign fibro‐osseous tumour of bones commonly involving the craniofacial region. Computed tomography (CT) imaging study of the disease is useful for evaluation and treatment planning. However, few studies have evaluated patient series in an African setting.

Material and methods:  A total of 14 patients with complete medical records and CT images were included in this study. All patients were non‐syndromic fibrous dysplasia involving only the craniofacial region. None had skin pigmentation or other evidence of endocrine problems. Data analysis was essentially on clinical and CT appearances of the lesions.

Results:  Facial swelling was the chief complaint in 79% of patients. Two patients were incidentally discovered after cranial CT scanning for head injury and stroke. The average number of bones involved was 5.4 per patient. Involvement of more than one craniofacial bone occurred in 78% of patients. The maxilla was involved in eight patients (57.14%), the ethmoidal, orbital and frontal bones were the most commonly jointly involved bones (64.3%). CT images appeared sclerotic or homogenous in 36%, ground glass or heterogeneous in 71% and cystic in 7%.

Conclusion:  CT features of craniofacial dysplasia in patients of African descent are similar to that seen in other racial groups. Our findings further suggest that craniofacial fibrous dysplasia can hardly be described as monostotic.
Transplantation of oral mucosa explants using different biological and synthetic membranes in an attempt to achieve one‐stage reconstruction of soft‐tissue defects
Authors: Moharamzadeh K. , Smith L.E. , Franklin K. , Ryan A.J. , Freeman C. , Thornhill M.H. , Brook I.M. , MacNeil S.
Published: July 2012

Aim:  The purpose of this study was to assess the effectiveness of combining freshly excised oral mucosa tissue with different biological and synthetic scaffolds for production of graft material for one‐stage soft‐tissue reconstruction.

Material and Methods:  Small oral mucosa biopsies were finely minced and transplanted onto a larger circular subcutaneous wound bed in rats. Test groups included explants seeded onto (1) an electrospun scaffold, (2) acellular dermis, and (3) directly on the muscle fascia. The soft‐tissue implants were examined using histology and immunohistochemical analysis for cytokeratins (CKs) 5, 10, 13, and 19.

Results:  Mucosal explants grew into fully developed epithelium with keratinisation. Surprisingly, instead of spreading over the surface of the membranes, the epithelial explants curled up and formed cyst‐like structures in all test groups. The epithelial layer of the cysts originated from mucosal explants grown on the electrospun scaffold showed weak positive staining for CK5, CK10, and CK19 similar to native rat oral mucosa. Other groups showed negative staining for the CKs.

Conclusions:  Subcutaneous transplantation of freshly excised oral mucosa explants resulted in the growth of the explants and formation of inclusion cyst‐like structures. The phenotype of the cyst epithelium was affected by the underlying connective tissue substrate.
Dental insurance, attitudes to dental care, and dental visiting
Authors: Teusner Dana N. , Brennan David S. , Spencer A. John
Published: July 2012

Objective: Dental insurance status is strongly associated with service use. In models of dental visiting, insurance is typically included as an enabling factor. However, in Australia, people self‐select into health insurance (privately purchased) and levels of cover for dental services are modest. Rather than enabling access, insurance status may be a “marker” for unmeasured predisposing attitudes. This study aims to explore associations between dental insurance status and visiting while adjusting for dental care attitudes.

Methods: Participants (South Australians aged 45‐54 years) of a 2‐year prospective cohort study (2005‐2007) investigating dental service use were surveyed on their attitudes to dental care and insurance status. Six attitudinal factors were assessed using a 23‐item Likert scale. Bivariate associations between insurance, attitudes, visiting, and other known covariates (age, sex, and household income) were explored. A series of regression models assessed whether prevalence ratios of visiting were attenuated after controlling for attitudinal factors.

Results: Response rate was 85.0 percent. Analysis was limited to dentate adults with known dental insurance status (n = 529). The majority had dental insurance (75.2%) and made regular visits (63.7%). Insurance status, visiting, and attitudinal factors were significantly associated. Controlling for covariates, insured adults, compared with the uninsured, were 57 percent more likely to make regular visits. After adjusting for attitudinal factors, the significant association between insurance and visiting persisted.

Conclusion: Dental care attitudes did not confound the association between dental insurance and visiting, indicating that dental insurance status was not a “marker” for predisposing attitudes.
Changes in carbon storage under alternative land uses in biodiverse Andean grasslands: implications for payment for ecosystem services
Authors: Farley Kathleen A. , Bremer Leah L. , Harden Carol P. , Hartsig James
Published: July 2012

Ecuadorian páramo grasslands have become the focus of Payment for Ecosystem Services programs that have promoted land‐use changes such as afforestation and reduction of burning, grazing of cattle or sheep, and agricultural expansion. However, limited information exists on the relationships between land use in páramos and the production of ecosystem services, including the direction and magnitude of changes in carbon storage. In an evaluation of eight sites representing incentivized land uses, we found significant differences in both soil carbon and aboveground carbon. The results support previous findings on the effects of pine plantations and suggest that limiting burning may be effective at enhancing carbon storage. They also indicate that, in highly productive grasslands such as the páramo, both belowground and aboveground C storage can be high, even when compared to some types of afforestation, providing support for greater attention to the role of grassland conservation in climate mitigation strategies.
Serum Iron Parameters and Acute Experimental EHV‐1 Infection in Horses
Authors: Brosnahan M.M. , Erb H.N. , Perkins G.A. , Divers T.J. , Borges A.S. , Osterrieder N.
Published: July 2012

Background

Research in humans has demonstrated that high serum iron (sFe) concentration can predispose to infection, and many infections subsequently result in alterations of host sFe. A decrease in sFe concentration is an early and sensitive indicator of systemic inflammation caused by tissue necrosis, bacterial infections, or endotoxemia in horses. Serum iron parameters in acute equine herpesvirus type 1 (EHV‐1) infection have not been evaluated previously.

Objectives

To document the sFe response to EHV‐1 infection and to determine whether or not significant differences in sFe concentration exist between EHV‐1 infected horses that develop neurologic disease and those that do not.

Animals

A total of 14 horses experimentally infected with EHV‐1.

Methods

Data were collected as an ancillary data set during a blinded experimental EHV‐1 infection. Horses were infected with the rAb4 strain of EHV‐1. Temperature, neurologic score, packed cell volume (PCV), and sFe parameters (sFe concentration, % saturation, and total iron‐binding capacity) were recorded daily for 2 weeks. Data were evaluated using Wilcoxon signed rank tests and Wilcoxon rank sum tests with Bonferroni corrections.

Conclusions and Clinical Relevance

Serum iron concentration decreases significantly in a biphasic pattern after EHV‐1 infection. There was no significant difference in sFe concentration in horses that developed neurologic disease and those that did not in these experimentally infected animals. Serum iron parameters may be useful in monitoring the clinical course of viral infections such as EHV‐1.
Effects of Stone-Wales Defects on the Thermal Conductivity of Carbon Nanotubes
Authors: Wei Li , Yanhui Feng , Jia Peng , Xinxin Zhang
Published: July 2012

The thermal conductivity of carbon nanotubes with Stone-Wales (SW) defects was investigated using non-equilibrium molecular dynamics method. The defect effects were analyzed by the temperature profile and local thermal resistance of the nanotubes with one or more SW defects and further compared with perfect tubes. The influences of the defect concentration, the length, the chirality and the radius of tubes and the ambient temperature were studied. It was demonstrated that a sharp jump in the temperature profile occurred at defect position due to a higher local thermal resistance, thus dramatically reducing the thermal conductivity of the nanotube. As the number of SW defects increases, the thermal conductivity decreases. Relative to the chirality, the radius has greater effects on the thermal conductivity of tubes with SW defects. With the similar radius, the thermal conductivity of armchair nanotube is higher than that of zigzag one. The shorter nanotube is more sensitive to the defect than the longer one. Thermal conductivity of the nanotube increases with ambient temperature, reaches a peak, and then decreases with increasing temperature.
Methane-Cycling Microbial Communities and Methane Emission in Natural and Restored Peatlands
Authors: Juottonen Heli , Hynninen Anu , Nieminen Mika , Tuomivirta Tero T. , Tuittila Eeva-Stiina , Nousiainen Hannu , Kell Dana K. , Yrjälä Kim , Tervahauta Arja , Fritze Hannu
Published: June 2012

We addressed how restoration of forestry-drained peatlands affects CH
4
-cycling microbes. Despite similar community compositions, the abundance of methanogens and methanotrophs was lower in restored than in natural sites and correlated with CH
4
emission. Poor establishment of methanogens may thus explain low CH
4
emissions on restored peatlands even 10 to 12 years after restoration.
Microbial Survey of a Full-Scale, Biologically Active Filter for Treatment of Drinking Water
Authors: White Colin P. , DeBry Ronald W. , Lytle Darren A.
Published: June 2012

The microbial community of a full-scale, biologically active drinking water filter was surveyed using molecular techniques.
Nitrosomonas
,
Nitrospira
,
Sphingomonadales
, and
Rhizobiales
dominated the clone libraries. The results elucidate the microbial ecology of biological filters and demonstrate that biological treatment of drinking water should be considered a viable alternative to physicochemical methods.
Pseudomonas aeruginosa Bacteriophage PA1Ø Requires Type IV Pili for Infection and Shows Broad Bactericidal and Biofilm Removal Activities
Authors: Kim Shukho , Rahman Marzia , Seol Sung Yong , Yoon Sang Sun , Kim Jungmin
Published: June 2012

We isolated a new lytic
Pseudomonas aeruginosa
phage that requires type IV pili for infection. PA1Ø has a broad bactericidal spectrum, covering Gram-positive and Gram-negative bacteria, and can eradicate biofilm cells. PA1Ø may be developed as a therapeutic agent for biofilm-related mixed infections with
P. aeruginosa
and
Staphylococcus aureus
.
Methanogenic Population and CH
4
Production in Swedish Dairy Cows Fed Different Levels of Forage
Authors: Danielsson R. , Schnürer A. , Arthurson V. , Bertilsson J.
Published: June 2012

Methanogenic community structure, methane production (CH
4
), and volatile fatty acid (VFA) profiles were investigated in Swedish dairy cows fed a diet with a forage/concentrate ratio of 500/500 or 900/100 g/kg of dry matter (DM) of total DM intake (DMI). The rumen methanogenic population was evaluated using terminal restriction fragment length polymorphism (T-RFLP) analysis, 16S rRNA gene libraries, and quantitative real-time PCR (qRT-PCR). Mean CH
4
yields did not differ (
P
> 0.05) between diets, being 16.9 and 20.2 g/kg DMI for the 500/500 and 900/100 diets, respectively. The T-RFLP analysis revealed that populations differed between individual cows and that each individual population responded differently to the diets. The 16S rRNA gene libraries revealed that
Methanobrevibacter
spp. dominated for both diets. CH
4
production was positively correlated with a dominance of sequences representing T-RFs related to
Methanobrevibacter thaueri
,
Methanobrevibacter millerae
, and
Methanobrevibacter smithii
relative to
Methanobrevibacter ruminantium
and
Methanobrevibacter olleyae
. Total numbers of methanogens and total numbers of
Methanobacteriales
were significantly higher with the 500/500 diet (
P
< 0.0004 and
P
< 0.002, respectively). However, no relationship was found between CH
4
production and total number of methanogens. No differences were seen in total VFA, propionic acid, or acetic acid contents, but the molar proportion of butyric acid in the rumen was higher for the 500/500 diet than for the 900/100 diet (
P
< 0.05). Interestingly, the results also revealed that a division of the identified methanogenic species into two groups, suggested in the work of King et al. (E. E. King, R. P. Smith, B. St-Pierre, and A. D. G. Wright, Appl. Environ. Microbiol.
77:
5682–5687, 2011), increased the understanding of the variation in CH
4
production between different cows.
Genetic Diversity, Symbiotic Evolution, and Proposed Infection Process of Bradyrhizobium Strains Isolated from Root Nodules of Aeschynomene americana L. in Thailand
Authors: Noisangiam Rujirek , Teamtisong Kamonluck , Tittabutr Panlada , Boonkerd Nantakorn , Toshiki Uchiumi , Minamisawa Kiwamu , Teaumroong Neung
Published: June 2012

The diversity of bacteria nodulatingAeschynomene americanaL. in Thailand was determined from phenotypic characteristics and multilocus sequence analysis of the 16S rRNA gene and 3 housekeeping genes (dnaK,recA, andglnB). The isolated strains were nonphotosynthetic bacteria and were assigned to the genusBradyrhizobium, in whichB. yuanmingensewas the dominant species. Some of the other species, includingB. japonicum,B. liaoningense, andB. canariense, were minor species. These isolated strains were divided into 2 groups—nod-containing and divergentnod-containing strains—based on Southern blot hybridization and PCR amplification ofnodABCgenes. The divergentnodgenes could not be PCR amplified and failed to hybridizenodgene probes designed fromB. japonicumUSDA110, but hybridized to probes from other bradyrhizobial strains under low-stringency conditions. The grouping based on sequence similarity ofnodgenes was well correlated with the grouping based on that ofnifHgene, in which thenod-containing and divergentnod-containing strains were obviously distinguished. The divergentnod-containing strains and photosynthetic bradyrhizobia shared closenifHsequence similarity and an ability to fix nitrogen in the free-living state. Surprisingly, the strains isolated fromA. americanacould nodulateAeschynomeneplants that belong to different cross-inoculation (CI) groups, includingA. afrasperaandA. indica. This is the first discovery of bradyrhizobia (nonphotosynthetic andnod-containing strain) originating from CI group 1 nodulating roots ofA. indica(CI group 3). An infection process used to establish symbiosis onAeschynomenedifferent from the classical one is proposed.
Consumption of Lysozyme-Rich Milk Can Alter Microbial Fecal Populations
Authors: Maga Elizabeth A. , Desai Prerak T. , Weimer Bart C. , Dao Nguyet , Kültz Dietmar , Murray James D.
Published: June 2012

Human milk contains antimicrobial factors such as lysozyme and lactoferrin that are thought to contribute to the development of an intestinal microbiota beneficial to host health. However, these factors are lacking in the milk of dairy animals. Here we report the establishment of an animal model to allow the dissection of the role of milk components in gut microbiota modulation and subsequent changes in overall and intestinal health. Using milk from transgenic goats expressing human lysozyme at 68%, the level found in human milk and young pigs as feeding subjects, the fecal microbiota was analyzed over time using 16S rRNA gene sequencing and the G2 Phylochip. The two methods yielded similar results, with the G2 Phylochip giving more comprehensive information by detecting more OTUs. Total community populations remained similar within the feeding groups, and community member diversity was changed significantly upon consumption of lysozyme milk. Levels of
Firmicutes
(
Clostridia
) declined whereas those of
Bacteroidetes
increased over time in response to the consumption of lysozyme-rich milk. The proportions of these major phyla were significantly different (
P
< 0.05) from the proportions seen with control-fed animals after 14 days of feeding. Within phyla, the abundance of bacteria associated with gut health (
Bifidobacteriaceae
and
Lactobacillaceae
) increased and the abundance of those associated with disease (
Mycobacteriaceae
,
Streptococcaceae
,
Campylobacterales
) decreased with consumption of lysozyme milk. This study demonstrated that a single component of the diet with bioactivity changed the gut microbiome composition. Additionally, this model enabled the direct examination of the impact of lysozyme on beneficial microbe enrichment versus detrimental microbe reduction in the gut microbiome community.
Lon Protease of Azorhizobium caulinodans ORS571 Is Required for Suppression of
reb
Gene Expression
Authors: Nakajima Azusa , Aono Toshihiro , Tsukada Shuhei , Siarot Lowela , Ogawa Tetsuhiro , Oyaizu Hiroshi
Published: June 2012

Bacterial Lon proteases play important roles in a variety of biological processes in addition to housekeeping functions. In this study, we focused on the Lon protease of
Azorhizobium caulinodans
, which can fix nitrogen both during free-living growth and in stem nodules of the legume
Sesbania rostrata
. The nitrogen fixation activity of an
A. caulinodans
lon
mutant in the free-living state was not significantly different from that of the wild-type strain. However, the stem nodules formed by the
lon
mutant showed little or no nitrogen fixation activity. By microscopic analyses, two kinds of host cells were observed in the stem nodules formed by the
lon
mutant. One type has shrunken host cells containing a high density of bacteria, and the other type has oval or elongated host cells containing a low density or no bacteria. This phenotype is similar to a
praR
mutant highly expressing the
reb
genes. Quantitative reverse transcription-PCR analyses revealed that
reb
genes were also highly expressed in the
lon
mutant. Furthermore, a
lon reb
double mutant formed stem nodules showing higher nitrogen fixation activity than the
lon
mutant, and shrunken host cells were not observed in these stem nodules. These results suggest that Lon protease is required to suppress the expression of the
reb
genes and that high expression of
reb
genes in part causes aberrance in the
A. caulinodans
-
S. rostrata
symbiosis. In addition to the suppression of
reb
genes, it was found that Lon protease was involved in the regulation of exopolysaccharide production and autoagglutination of bacterial cells.
Upper Respiratory Tract Microbial Communities, Acute Otitis Media Pathogens, and Antibiotic Use in Healthy and Sick Children
Authors: Pettigrew Melinda M. , Laufer Alison S. , Gent Janneane F. , Kong Yong , Fennie Kristopher P. , Metlay Joshua P.
Published: June 2012

The composition of the upper respiratory tract microbial community may influence the risk for colonization by the acute otitis media (AOM) pathogens
Streptococcus pneumoniae
,
Haemophilus influenzae
, and
Moraxella catarrhalis
. We used culture-independent methods to describe upper respiratory tract microbial communities in healthy children and children with upper respiratory tract infection with and without concurrent AOM. Nasal swabs and data were collected in a cross-sectional study of 240 children between 6 months and 3 years of age. Swabs were cultured for
S. pneumoniae
, and real-time PCR was used to identify
S. pneumoniae
,
H. influenzae
, and
M. catarrhalis
. The V1-V2 16S rRNA gene regions were sequenced using 454 pyrosequencing. Microbial communities were described using a taxon-based approach. Colonization by
S. pneumoniae
,
H. influenzae
, and
M. catarrhalis
was associated with lower levels of diversity in upper respiratory tract flora. We identified commensal taxa that were negatively associated with colonization by each AOM bacterial pathogen and with AOM. The balance of these relationships differed according to the colonizing AOM pathogen and history of antibiotic use. Children with antibiotic use in the past 6 months and a greater abundance of taxa, including
Lactococcus
and
Propionibacterium
, were less likely to have AOM than healthy children (odds ratio [OR], 0.46; 95% confidence interval [CI], 0.25 to 0.85). Children with no antibiotic use in the past 6 months, a low abundance of
Streptococcus
and
Haemophilus
, and a high abundance of
Corynebacterium
and
Dolosigranulum
were less likely to have AOM (OR, 0.51; 95% CI, 0.31 to 0.83). An increased understanding of polymicrobial interactions will facilitate the development of effective AOM prevention strategies.
Enhanced Inactivation of Salmonella and Pseudomonas Biofilms on Stainless Steel by Use of T-128, a Fresh-Produce Washing Aid, in Chlorinated Wash Solutions
Authors: Shen Cangliang , Luo Yaguang , Nou Xiangwu , Bauchan Gary , Zhou Bin , Wang Qin , Millner Patricia
Published: June 2012

The effect of the washing aid T-128 (generally recognized as safe [GRAS] formulation, composed mainly of phosphoric acid and propylene glycol) on inactivation of
Salmonella
and
Pseudomonas
populations in biofilms on stainless steel was evaluated under conditions of increasing organic matter loads in chlorinated wash solutions dominated by hypochlorous acid. Biofilms were formed statically on stainless steel coupons suspended in 2% lettuce extract after inoculation with
Salmonella enterica
serovar Thompson or Newport or with
Pseudomonas fluorescens
. Coupons with biofilms were washed in chlorine solutions (0, 0.5, 1, 2, 5, 10, or 20 mg/liter at pH 6.5, 5.0 and 2.9), with or without T-128, and with increasing loads of organic matter (0, 0.25, 0.5, 0.75, or 1.0% lettuce extract). Cell populations on coupons were dispersed using intermittent, pulsed ultrasonication and vortexing and enumerated by colony counts on XLT-4 or
Pseudomonas
agars. Cell responses to fluorescent viability staining of biofilm treatment washing solutions were examined using confocal laser scanning microscopy. Results showed that 0.1% T-128 (without chlorine) reduced
P. fluorescens
biofilm populations by 2.5 log
10
units but did not reduce
Salmonella
populations. For both
Salmonella
and
Pseudomonas
, the sanitizing effect of free chlorine (1.0 to 5.0 mg/liter) was enhanced (
P
< 0.05) when it was combined with T-128. Application of T-128 decreased the free chlorine depletion rate caused by increasing organic matter in wash waters and significantly (
P
< 0.05) augmented inactivation of bacteria in biofilms compared to treatments without T-128. Image analysis of surfaces stained with SYTO and propidium iodide corroborate the cultural assay results showing that T-128 can aid in reducing pathogen viability in biofilms and thus can aid in sanitizing stainless steel contact surfaces during processing of fresh-cut produce.
Inactivation of Chloramphenicol and Florfenicol by a Novel Chloramphenicol Hydrolase
Authors: Tao Weixin , Lee Myung Hwan , Wu Jing , Kim Nam Hee , Kim Jin-Cheol , Chung Eunsook , Hwang Eul Chul , Lee Seon-Woo
Published: June 2012

Chloramphenicol and florfenicol are broad-spectrum antibiotics. Although the bacterial resistance mechanisms to these antibiotics have been well documented, hydrolysis of these antibiotics has not been reported in detail. This study reports the hydrolysis of these two antibiotics by a specific hydrolase that is encoded by a gene identified from a soil metagenome. Hydrolysis of chloramphenicol has been recognized in cell extracts of
Escherichia coli
expressing a chloramphenicol acetate esterase gene,
estDL136
. A hydrolysate of chloramphenicol was identified as
p
-nitrophenylserinol by liquid chromatography-mass spectroscopy and proton nuclear magnetic resonance spectroscopy. The hydrolysis of these antibiotics suggested a promiscuous amidase activity of EstDL136. When
estDL136
was expressed in
E. coli
, EstDL136 conferred resistance to both chloramphenicol and florfenicol on
E. coli
, due to their inactivation. In addition,
E. coli
carrying
estDL136
deactivated florfenicol faster than it deactivated chloramphenicol, suggesting that EstDL136 hydrolyzes florfenicol more efficiently than it hydrolyzes chloramphenicol. The nucleotide sequences flanking
estDL136
encode proteins such as amidohydrolase, dehydrogenase/reductase, major facilitator transporter, esterase, and oxidase. The most closely related genes are found in the bacterial family
Sphingomonadaceae
, which contains many bioremediation-related strains. Whether the gene cluster with
estDL136
in
E. coli
is involved in further chloramphenicol degradation was not clear in this study. While acetyltransferases for chloramphenicol resistance and drug exporters for chloramphenicol or florfenicol resistance are often detected in numerous microbes, this is the first report of enzymatic hydrolysis of florfenicol resulting in inactivation of the antibiotic.
Protection of Bacillus pumilus Spores by Catalases
Authors: Checinska Aleksandra , Burbank Malcolm , Paszczynski Andrzej J.
Published: June 2012

Bacillus pumilus
SAFR-032, isolated at spacecraft assembly facilities of the National Aeronautics and Space Administration Jet Propulsion Laboratory, is difficult to kill by the sterilization method of choice, which uses liquid or vapor hydrogen peroxide. We identified two manganese catalases, YjqC and BPUM_1305, in spore protein extracts of several
B. pumilus
strains by using PAGE and mass spectrometric analyses. While the BPUM_1305 catalase was present in six of the
B. pumilus
strains tested, YjqC was not detected in ATCC 7061 and BG-B79. Furthermore, both catalases were localized in the spore coat layer along with laccase and superoxide dismutase. Although the initial catalase activity in ATCC 7061 spores was higher, it was less stable over time than the SAFR-032 enzyme. We propose that synergistic activity of YjqC and BPUM_1305, along with other coat oxidoreductases, contributes to the enhanced resistance of
B. pumilus
spores to hydrogen peroxide. We observed that the product of the catalase reaction, gaseous oxygen, forms expanding vesicles on the spore surface, affecting the mechanical integrity of the coat layer, resulting in aggregation of the spores. The accumulation of oxygen gas and aggregations may play a crucial role in limiting further exposure of
Bacilli
spore surfaces to hydrogen peroxide or other toxic chemicals when water is present.
Internalization of Sapovirus, a Surrogate for Norovirus, in Romaine Lettuce and the Effect of Lettuce Latex on Virus Infectivity
Authors: Esseili Malak A. , Wang Qiuhong , Zhang Zhenwen , Saif Linda J.
Published: June 2012

Noroviruses are the leading cause of food-borne outbreaks, including those that involve lettuce. The culturable porcine sapovirus (SaV) was used as a norovirus surrogate to study the persistence and the potential transfer of the virus from roots to leaves and from outer to inner leaves of lettuce plants. Treatment of lettuce with SaV was done through the roots of young plants, the soil, or the outer leaves of mature plants. Sampling of roots, xylem sap, and inner and outer leaves followed by RNA extraction and SaV-specific real-time reverse transcription (RT)-PCR was performed at 2 h and on postinoculation days (PID) 2, 5, 7, 14, and/or 28. When SaV was inoculated through the roots, viral RNA persisted on the roots and in the leaves until PID 28. When the virus was inoculated through the soil, viral RNA was detected on the roots and in the xylem sap until PID 14; viral RNA was detected in the leaves only until PID 2. No infectious virus was detected inside the leaves for either treatment. When SaV was inoculated through the outer leaves, viral RNA persisted on the leaves until PID 14; however, the virus did not transfer to inner leaves. Infectious viral particles on leaves were detected only at 2 h postinoculation. The milky sap (latex) of leaves, but not the roots' xylem sap, significantly decreased virus infectivity when tested
in vitro
. Collectively, our results showed the transfer of SaV from roots to leaves through the xylem system and the capacity of the sap of lettuce leaves to decrease virus infectivity in leaves.
Epimerase (Msed_0639) and Mutase (Msed_0638 and Msed_2055) Convert (
S
)-Methylmalonyl-Coenzyme A (CoA) to Succinyl-CoA in the Metallosphaera sedula 3-Hydroxypropionate/4-Hydroxybutyrate Cycle
Authors: Han Yejun , Hawkins Aaron S. , Adams Michael W. W. , Kelly Robert M.
Published: June 2012

Crenarchaeotal genomes encode the 3-hydroxypropionate/4-hydroxybutyrate (3-HP/4-HB) cycle for carbon dioxide fixation. Of the 13 enzymes putatively comprising the cycle, several of them, including methylmalonyl-coenzyme A (CoA) epimerase (MCE) and methylmalonyl-CoA mutase (MCM), which convert (
S
)-methylmalonyl-CoA to succinyl-CoA, have not been confirmed and characterized biochemically. In the genome of
Metallosphaera sedula
(optimal temperature [
T
opt
], 73°C), the gene encoding MCE (Msed_0639) is adjacent to that encoding the catalytic subunit of MCM-α (Msed_0638), while the gene for the coenzyme B
12
-binding subunit of MCM (MCM-β) is located remotely (Msed_2055). The expression of all three genes was significantly upregulated under autotrophic compared to heterotrophic growth conditions, implying a role in CO
2
fixation. Recombinant forms of MCE and MCM were produced in
Escherichia coli
; soluble, active MCM was produced only if MCM-α and MCM-β were coexpressed. MCE is a homodimer and MCM is a heterotetramer (α
2
β
2
) with specific activities of 218 and 2.2 μmol/min/mg, respectively, at 75°C. The heterotetrameric MCM differs from the homo- or heterodimeric orthologs in other organisms. MCE was activated by divalent cations (Ni
2+
, Co
2+
, and Mg
2+
), and the predicted metal binding/active sites were identified through sequence alignments with less-thermophilic MCEs. The conserved coenzyme B
12
-binding motif (
DXHXXG
-SXL-GG) was identified in
M. sedula
MCM-β. The two enzymes together catalyzed the two-step conversion of (
S
)-methylmalonyl-CoA to succinyl-CoA, consistent with their proposed role in the 3-HP/4-HB cycle. Based on the highly conserved occurrence of single copies of MCE and MCM in
Sulfolobaceae
genomes, the
M. sedula
enzymes are likely to be representatives of these enzymes in the 3-HP/4-HB cycle in crenarchaeal thermoacidophiles.
Peculiar H
+
Homeostasis of Saccharomyces cerevisiae during the Late Stages of Wine Fermentation
Authors: Viana Tiago , Loureiro-Dias Maria C. , Loureiro Virgílio , Prista Catarina
Published: June 2012

Intracellular pH (pH
in
) is a tightly regulated physiological parameter, which controls cell performance in all living systems. The purpose of this work was to evaluate if and how H
+
homeostasis is accomplished by an industrial wine strain of
Saccharomyces cerevisiae
while fermenting real must under the harsh winery conditions prevalent in the late stages of the fermentation process, in particular low pH and high ethanol concentrations and temperature. Cells grown at 15, 25, and 30°C were harvested in exponential and early and late stationary phases. Intracellular pH remained in the range of 6.0 to 6.4, decreasing significantly only by the end of glucose fermentation, in particular at lower temperatures (pH
in
5.2 at 15°C), although the cells remained viable and metabolically active. The cell capability of extruding H
+
via H
+
-ATPase and of keeping H
+
out by means of an impermeable membrane were evaluated as potential mechanisms of H
+
homeostasis. At 30°C, H
+
efflux was higher in all stages. The most striking observation was that cells in late stationary phase became almost impermeable to H
+
. Even when these cells were challenged with high ethanol concentrations (up to 20%) added in the assay, their permeability to H
+
remained very low, being almost undetectable at 15°C. Comparatively, ethanol significantly increased the H
+
permeability of cells in exponential phase. Understanding the molecular and physiological events underlying yeast H
+
homeostasis at late stages of fermentations may contribute to the development of more robust strains suitable to efficiently produce a high-quality wine.
Synthesis of Short-Chain Diols and Unsaturated Alcohols from Secondary Alcohol Substrates by the Rieske Nonheme Mononuclear Iron Oxygenase MdpJ
Authors: Schäfer Franziska , Schuster Judith , Würz Birgit , Härtig Claus , Harms Hauke , Müller Roland H. , Rohwerder Thore
Published: June 2012

The Rieske nonheme mononuclear iron oxygenase MdpJ of the fuel oxygenate-degrading bacterial strain
Aquincola tertiaricarbonis
L108 has been described to attack short-chain tertiary alcohols via hydroxylation and desaturation reactions. Here, we demonstrate that also short-chain secondary alcohols can be transformed by MdpJ. Wild-type cells of strain L108 converted 2-propanol and 2-butanol to 1,2-propanediol and 3-buten-2-ol, respectively, whereas an
mdpJ
knockout mutant did not show such activity. In addition, wild-type cells converted 3-methyl-2-butanol and 3-pentanol to the corresponding desaturation products 3-methyl-3-buten-2-ol and 1-penten-3-ol, respectively. The enzymatic hydroxylation of 2-propanol resulted in an enantiomeric excess of about 70% for the (
R
)-enantiomer, indicating that this reaction was favored. Likewise, desaturation of (
R
)-2-butanol to 3-buten-2-ol was about 2.3-fold faster than conversion of the (
S
)-enantiomer. The biotechnological potential of MdpJ for the synthesis of enantiopure short-chain alcohols and diols as building block chemicals is discussed.
Molecular Survey of the Occurrence of Legionella spp., Mycobacterium spp., Pseudomonas aeruginosa, and Amoeba Hosts in Two Chloraminated Drinking Water Distribution Systems
Authors: Wang Hong , Edwards Marc , Falkinham Joseph O. , Pruden Amy
Published: June 2012

The spread of opportunistic pathogens via public water systems is of growing concern. The purpose of this study was to identify patterns of occurrence among three opportunistic pathogens (
Legionella pneumophila
,
Mycobacterium avium
, and
Pseudomonas aeruginosa
) relative to biotic and abiotic factors in two representative chloraminated drinking water distribution systems using culture-independent methods. Generally, a high occurrence of
Legionella
(≥69.0%) and mycobacteria (100%), lower occurrence of
L. pneumophila
(≤20%) and
M. avium
(≤33.3%), and rare detection of
Pseudomonas aeruginosa
(≤13.3%) were observed in both systems according to quantitative PCR. Also,
Hartmanella vermiformis
was more prevalent than
Acanthamoeba
, both of which are known hosts for opportunistic pathogen amplification, the latter itself containing pathogenic members. Three-minute flushing served to distinguish distribution system water from plumbing in buildings (i.e., premise plumbing water) and resulted in reduced numbers of copies of
Legionella
, mycobacteria,
H. vermiformis
, and 16S rRNA genes (
P
< 0.05) while yielding distinct terminal restriction fragment polymorphism (T-RFLP) profiles of 16S rRNA genes. Within certain subgroups of samples, some positive correlations, including correlations of numbers of mycobacteria and total bacteria (16S rRNA genes),
H. vermiformis
and total bacteria, mycobacteria and
H. vermiformis
, and
Legionella
and
H. vermiformis
, were noted, emphasizing potential microbial ecological relationships. Overall, the results provide insight into factors that may aid in controlling opportunistic pathogen proliferation in real-world water systems.
Membrane Vesicle Formation as a Multiple-Stress Response Mechanism Enhances Pseudomonas putida DOT-T1E Cell Surface Hydrophobicity and Biofilm Formation
Authors: Baumgarten Thomas , Sperling Stefanie , Seifert Jana , von Bergen Martin , Steiniger Frank , Wick Lukas Y. , Heipieper Hermann J.
Published: June 2012

Among the adaptive responses of bacteria to rapid changes in environmental conditions, those of the cell envelope are known to be the most crucial. Therefore, several mechanisms with which bacteria change their cell surface and membranes in the presence of different environmental stresses have been elucidated. Among these mechanisms, the release of outer membrane vesicles (MV) in Gram-negative bacteria has attracted particular research interest because of its involvement in pathogenic processes, such as that of
Pseudomonas aeruginosa
biofilm formation in cystic fibrosis lungs. In this study, we investigated the role of MV formation as an adaptive response of
Pseudomonas putida
DOT-T1E to several environmental stress factors and correlated it to the formation of biofilms. In the presence of toxic concentrations of long-chain alcohols, under osmotic stress caused by NaCl, in the presence of EDTA, and after heat shock, cells of this strain released MV within 10 min in the presence of a stressor. The MV formed showed similar size and charge properties, as well as comparable compositions of proteins and fatty acids. MV release caused a significant increase in cell surface hydrophobicity, and an enhanced tendency to form biofilms was demonstrated in this study. Therefore, the release of MV as a stress response could be put in a physiological context.
Structural Insights into the Regulatory Mechanism of the Response Regulator RocR from Pseudomonas aeruginosa in Cyclic Di-GMP Signaling
Authors: Chen Ming Wei , Kotaka Masayo , Vonrhein Clemens , Bricogne Gérard , Rao Feng , Chuah Mary Lay Cheng , Svergun Dmitri , Schneider Gunter , Liang Zhao-Xun , Lescar Julien
Published: June 2012

The nucleotide messenger cyclic di-GMP (c-di-GMP) plays a central role in the regulation of motility, virulence, and biofilm formation in many pathogenic bacteria. EAL domain-containing phosphodiesterases are the major signaling proteins responsible for the degradation of c-di-GMP and maintenance of its cellular level. We determined the crystal structure of a single mutant (R286W) of the response regulator RocR fromPseudomonas aeruginosato show that RocR exhibits a highly unusual tetrameric structure arranged around a single dyad, with the four subunits adopting two distinctly different conformations. Subunits A and B adopt a conformation with the REC domain located above the c-di-GMP binding pocket, whereas subunits C and D adopt an open conformation with the REC domain swung to the side of the EAL domain. Remarkably, the access to the substrate-binding pockets of the EAL domains of the open subunits C and D are blocked intransby the REC domains of subunits A and B, indicating that only two of the four active sites are engaged in the degradation of c-di-GMP. In conjunction with biochemical and biophysical data, we propose that the structural changes within the REC domains triggered by the phosphorylation are transmitted to the EAL domain active sites through a pathway that traverses the dimerization interfaces composed of a conserved regulatory loop and the neighboring motifs. This exquisite mechanism reinforces the crucial role of the regulatory loop and suggests that similar regulatory mechanisms may be operational in many EAL domain proteins, considering the preservation of the dimerization interface and the spatial arrangement of the regulatory domains.
Pseudomonas aeruginosa Directly Shunts β-Oxidation Degradation Intermediates into
De Novo
Fatty Acid Biosynthesis
Authors: Yuan Yanqiu , Leeds Jennifer A. , Meredith Timothy C.
Published: June 2012

We identified the fatty acid synthesis (FAS) initiation enzyme in
Pseudomonas aeruginosa
as FabY, a β-ketoacyl synthase KASI/II domain-containing enzyme that condenses acetyl coenzyme A (acetyl-CoA) with malonyl-acyl carrier protein (ACP) to make the FAS primer β-acetoacetyl-ACP in the
accompanying article
(Y. Yuan, M. Sachdeva, J. A. Leeds, and T. C. Meredith, J. Bacteriol. 194:5171-5184, 2012). Herein, we show that growth defects stemming from deletion of
fabY
can be suppressed by supplementation of the growth media with exogenous decanoate fatty acid, suggesting a compensatory mechanism. Fatty acids eight carbons or longer rescue growth by generating acyl coenzyme A (acyl-CoA) thioester β-oxidation degradation intermediates that are shunted into FAS downstream of FabY. Using a set of perdeuterated fatty acid feeding experiments, we show that the open reading frame PA3286 in
P. aeruginosa
PAO1 intercepts C
8
-CoA by condensation with malonyl-ACP to make the FAS intermediate β-keto decanoyl-ACP. This key intermediate can then be extended to supply all of the cellular fatty acid needs, including both unsaturated and saturated fatty acids, along with the 3-hydroxyl fatty acid acyl groups of lipopolysaccharide. Heterologous PA3286 expression in
Escherichia coli
likewise established the fatty acid shunt, and characterization of recombinant β-keto acyl synthase enzyme activity confirmed
in vitro
substrate specificity for medium-chain-length acyl CoA thioester acceptors. The potential for the PA3286 shunt in
P. aeruginosa
to curtail the efficacy of inhibitors targeting FabY, an enzyme required for FAS initiation in the absence of exogenous fatty acids, is discussed.